Down-integrate from google internal.

112 files changed, 3562 insertions, 962 deletions

diff --git a/Makefile.am b/Makefile.am
index 82ce190d..e4dce6e5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -505,6 +505,7 @@ python_EXTRA_DIST=                                                           \
   python/google/protobuf/internal/factory_test1.proto                        \
   python/google/protobuf/internal/factory_test2.proto                        \
   python/google/protobuf/internal/generator_test.py                          \
+  python/google/protobuf/internal/json_format_test.py                        \
   python/google/protobuf/internal/message_factory_test.py                    \
   python/google/protobuf/internal/message_listener.py                        \
   python/google/protobuf/internal/message_set_extensions.proto               \
@@ -560,6 +561,7 @@ python_EXTRA_DIST=                                                           \
   python/google/protobuf/descriptor.py                                       \
   python/google/protobuf/descriptor_database.py                              \
   python/google/protobuf/descriptor_pool.py                                  \
+  python/google/protobuf/json_format.py                                      \
   python/google/protobuf/message.py                                          \
   python/google/protobuf/message_factory.py                                  \
   python/google/protobuf/proto_builder.py                                    \
diff --git a/appveyor.yml b/appveyor.yml
index 3447602e..c84ecae2 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -1,32 +1,32 @@
-# Only test one combination: "Visual Studio 12 + Win64 + Debug + DLL". We can

-# test more combinations but AppVeyor just takes too long to finish (each

-# combination takes ~15mins).

-platform:

-  - Win64

-

-configuration:

-  - Debug

-

-environment:

-  matrix:

-    - language: cpp

-      BUILD_DLL: ON

-

-    - language: csharp

-

-install:

-  - ps: Start-FileDownload https://googlemock.googlecode.com/files/gmock-1.7.0.zip

-  - 7z x gmock-1.7.0.zip

-  - rename gmock-1.7.0 gmock

-

-before_build:

-  - if %platform%==Win32 set generator=Visual Studio 12

-  - if %platform%==Win64 set generator=Visual Studio 12 Win64

-  - if %platform%==Win32 set vcplatform=Win32

-  - if %platform%==Win64 set vcplatform=x64

-

-build_script:

-  - CALL appveyor.bat

-

-skip_commits:

-  message: /.*\[skip appveyor\].*/

+# Only test one combination: "Visual Studio 12 + Win64 + Debug + DLL". We can
+# test more combinations but AppVeyor just takes too long to finish (each
+# combination takes ~15mins).
+platform:
+  - Win64
+
+configuration:
+  - Debug
+
+environment:
+  matrix:
+    - language: cpp
+      BUILD_DLL: ON
+
+    - language: csharp
+
+install:
+  - ps: Start-FileDownload https://googlemock.googlecode.com/files/gmock-1.7.0.zip
+  - 7z x gmock-1.7.0.zip
+  - rename gmock-1.7.0 gmock
+
+before_build:
+  - if %platform%==Win32 set generator=Visual Studio 12
+  - if %platform%==Win64 set generator=Visual Studio 12 Win64
+  - if %platform%==Win32 set vcplatform=Win32
+  - if %platform%==Win64 set vcplatform=x64
+
+build_script:
+  - CALL appveyor.bat
+
+skip_commits:
+  message: /.*\[skip appveyor\].*/
diff --git a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
index a535b718..4316efee 100644
--- a/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
+++ b/java/src/main/java/com/google/protobuf/GeneratedMessageLite.java
@@ -62,9 +62,8 @@ public abstract class GeneratedMessageLite<
 
   private static final long serialVersionUID = 1L;
 
-  /** For use by generated code only.  */
-  protected UnknownFieldSetLite unknownFields =
-      UnknownFieldSetLite.getDefaultInstance();
+  /** For use by generated code only. Lazily initialized to reduce allocations. */
+  protected UnknownFieldSetLite unknownFields = null;
   
   /** For use by generated code only.  */
   protected int memoizedSerializedSize = -1;
@@ -84,19 +83,56 @@ public abstract class GeneratedMessageLite<
     return (BuilderType) dynamicMethod(MethodToInvoke.NEW_BUILDER);
   }
 
+  // The general strategy for unknown fields is to use an UnknownFieldSetLite that is treated as
+  // mutable during the parsing constructor and immutable after. This allows us to avoid
+  // any unnecessary intermediary allocations while reducing the generated code size.
+
+  /**
+   * Lazily initializes unknown fields.
+   */
+  private final void ensureUnknownFieldsInitialized() {
+    if (unknownFields == null) {
+      unknownFields = UnknownFieldSetLite.newInstance();
+    }
+  }
+  
   /**
-   * Called by subclasses to parse an unknown field. For use by generated code
-   * only.
+   * Called by subclasses to parse an unknown field. For use by generated code only.
+   * 
    * @return {@code true} unless the tag is an end-group tag.
    */
-  protected static boolean parseUnknownField(
-      CodedInputStream input,
-      UnknownFieldSetLite.Builder unknownFields,
-      ExtensionRegistryLite extensionRegistry,
-      int tag) throws IOException {
+  protected boolean parseUnknownField(int tag, CodedInputStream input) throws IOException {
+    ensureUnknownFieldsInitialized();
     return unknownFields.mergeFieldFrom(tag, input);
   }
 
+  /**
+   * Called by subclasses to parse an unknown field. For use by generated code only.
+   */
+  protected void mergeVarintField(int tag, int value) {
+    ensureUnknownFieldsInitialized();
+    unknownFields.mergeVarintField(tag, value);
+  }
+  
+  /**
+   * Called by subclasses to parse an unknown field. For use by generated code only.
+   */
+  protected void mergeLengthDelimitedField(int fieldNumber, ByteString value) {
+    ensureUnknownFieldsInitialized();
+    unknownFields.mergeLengthDelimitedField(fieldNumber, value);
+  }
+  
+  /**
+   * Called by subclasses to complete parsing. For use by generated code only.
+   */
+  protected void doneParsing() {
+    if (unknownFields == null) {
+      unknownFields = UnknownFieldSetLite.getDefaultInstance();
+    } else {
+      unknownFields.makeImmutable();
+    }
+  }
+
   public final boolean isInitialized() {
     return dynamicMethod(MethodToInvoke.IS_INITIALIZED, Boolean.TRUE) != null;
   }
@@ -171,7 +207,7 @@ public abstract class GeneratedMessageLite<
    * <p>For use by generated code only.
    */
   protected final void mergeUnknownFields(UnknownFieldSetLite unknownFields) {
-    this.unknownFields = UnknownFieldSetLite.concat(this.unknownFields, unknownFields);
+    this.unknownFields = UnknownFieldSetLite.mutableCopyOf(this.unknownFields, unknownFields);
   }
 
   @SuppressWarnings("unchecked")
@@ -225,7 +261,13 @@ public abstract class GeneratedMessageLite<
 
     //@Override (Java 1.6 override semantics, but we must support 1.5)
     public MessageType buildPartial() {
+      if (isBuilt) {
+        return instance;
+      }
+      
       instance.dynamicMethod(MethodToInvoke.MAKE_IMMUTABLE);
+      instance.unknownFields.makeImmutable();
+      
       isBuilt = true;
       return instance;
     }
@@ -249,18 +291,6 @@ public abstract class GeneratedMessageLite<
     public MessageType getDefaultInstanceForType() {
       return defaultInstance;
     }
-
-    /**
-     * Called by subclasses to parse an unknown field.
-     * @return {@code true} unless the tag is an end-group tag.
-     */
-    protected boolean parseUnknownField(
-        CodedInputStream input,
-        UnknownFieldSetLite.Builder unknownFields,
-        ExtensionRegistryLite extensionRegistry,
-        int tag) throws IOException {
-      return unknownFields.mergeFieldFrom(tag, input);
-    }
     
     public BuilderType mergeFrom(
         com.google.protobuf.CodedInputStream input,
@@ -334,6 +364,130 @@ public abstract class GeneratedMessageLite<
       extensions.mergeFrom(((ExtendableMessage) other).extensions);
     }
     
+    /**
+     * Parse an unknown field or an extension. For use by generated code only.
+     * 
+     * <p>For use by generated code only.
+     * 
+     * @return {@code true} unless the tag is an end-group tag.
+     */
+    protected <MessageType extends MessageLite> boolean parseUnknownField(
+        MessageType defaultInstance,
+        CodedInputStream input,
+        ExtensionRegistryLite extensionRegistry,
+        int tag) throws IOException {
+      int wireType = WireFormat.getTagWireType(tag);
+      int fieldNumber = WireFormat.getTagFieldNumber(tag);
+
+      // TODO(dweis): How much bytecode would be saved by not requiring the generated code to
+      //     provide the default instance?
+      GeneratedExtension<MessageType, ?> extension = extensionRegistry.findLiteExtensionByNumber(
+          defaultInstance, fieldNumber);
+
+      boolean unknown = false;
+      boolean packed = false;
+      if (extension == null) {
+        unknown = true;  // Unknown field.
+      } else if (wireType == FieldSet.getWireFormatForFieldType(
+                   extension.descriptor.getLiteType(),
+                   false  /* isPacked */)) {
+        packed = false;  // Normal, unpacked value.
+      } else if (extension.descriptor.isRepeated &&
+                 extension.descriptor.type.isPackable() &&
+                 wireType == FieldSet.getWireFormatForFieldType(
+                   extension.descriptor.getLiteType(),
+                   true  /* isPacked */)) {
+        packed = true;  // Packed value.
+      } else {
+        unknown = true;  // Wrong wire type.
+      }
+
+      if (unknown) {  // Unknown field or wrong wire type.  Skip.
+        return parseUnknownField(tag, input);
+      }
+
+      if (packed) {
+        int length = input.readRawVarint32();
+        int limit = input.pushLimit(length);
+        if (extension.descriptor.getLiteType() == WireFormat.FieldType.ENUM) {
+          while (input.getBytesUntilLimit() > 0) {
+            int rawValue = input.readEnum();
+            Object value =
+                extension.descriptor.getEnumType().findValueByNumber(rawValue);
+            if (value == null) {
+              // If the number isn't recognized as a valid value for this
+              // enum, drop it (don't even add it to unknownFields).
+              return true;
+            }
+            extensions.addRepeatedField(extension.descriptor,
+                                        extension.singularToFieldSetType(value));
+          }
+        } else {
+          while (input.getBytesUntilLimit() > 0) {
+            Object value =
+                FieldSet.readPrimitiveField(input,
+                                            extension.descriptor.getLiteType(),
+                                            /*checkUtf8=*/ false);
+            extensions.addRepeatedField(extension.descriptor, value);
+          }
+        }
+        input.popLimit(limit);
+      } else {
+        Object value;
+        switch (extension.descriptor.getLiteJavaType()) {
+          case MESSAGE: {
+            MessageLite.Builder subBuilder = null;
+            if (!extension.descriptor.isRepeated()) {
+              MessageLite existingValue =
+                  (MessageLite) extensions.getField(extension.descriptor);
+              if (existingValue != null) {
+                subBuilder = existingValue.toBuilder();
+              }
+            }
+            if (subBuilder == null) {
+              subBuilder = extension.getMessageDefaultInstance()
+                  .newBuilderForType();
+            }
+            if (extension.descriptor.getLiteType() ==
+                WireFormat.FieldType.GROUP) {
+              input.readGroup(extension.getNumber(),
+                              subBuilder, extensionRegistry);
+            } else {
+              input.readMessage(subBuilder, extensionRegistry);
+            }
+            value = subBuilder.build();
+            break;
+          }
+          case ENUM:
+            int rawValue = input.readEnum();
+            value = extension.descriptor.getEnumType()
+                             .findValueByNumber(rawValue);
+            // If the number isn't recognized as a valid value for this enum,
+            // write it to unknown fields object.
+            if (value == null) {
+              mergeVarintField(fieldNumber, rawValue);
+              return true;
+            }
+            break;
+          default:
+            value = FieldSet.readPrimitiveField(input,
+                extension.descriptor.getLiteType(),
+                /*checkUtf8=*/ false);
+            break;
+        }
+
+        if (extension.descriptor.isRepeated()) {
+          extensions.addRepeatedField(extension.descriptor,
+                                      extension.singularToFieldSetType(value));
+        } else {
+          extensions.setField(extension.descriptor,
+                              extension.singularToFieldSetType(value));
+        }
+      }
+
+      return true;
+    }
+    
     private void verifyExtensionContainingType(
         final GeneratedExtension<MessageType, ?> extension) {
       if (extension.getContainingTypeDefaultInstance() !=
@@ -404,11 +558,10 @@ public abstract class GeneratedMessageLite<
     }
 
 
-    /**
-     * Used by parsing constructors in generated classes.
-     */
-    protected static void makeExtensionsImmutable(
-        FieldSet<ExtensionDescriptor> extensions) {
+    @Override
+    protected final void doneParsing() {
+      super.doneParsing();
+      
       extensions.makeImmutable();
     }
 
@@ -619,131 +772,6 @@ public abstract class GeneratedMessageLite<
     }
   }
 
-  //-----------------------------------------------------------------
-
-  /**
-   * Parse an unknown field or an extension. For use by generated code only.
-   * @return {@code true} unless the tag is an end-group tag.
-   */
-  protected static <MessageType extends MessageLite>
-      boolean parseUnknownField(
-          FieldSet<ExtensionDescriptor> extensions,
-          MessageType defaultInstance,
-          CodedInputStream input,
-          UnknownFieldSetLite.Builder unknownFields,
-          ExtensionRegistryLite extensionRegistry,
-          int tag) throws IOException {
-    int wireType = WireFormat.getTagWireType(tag);
-    int fieldNumber = WireFormat.getTagFieldNumber(tag);
-
-    GeneratedExtension<MessageType, ?> extension =
-      extensionRegistry.findLiteExtensionByNumber(
-          defaultInstance, fieldNumber);
-
-    boolean unknown = false;
-    boolean packed = false;
-    if (extension == null) {
-      unknown = true;  // Unknown field.
-    } else if (wireType == FieldSet.getWireFormatForFieldType(
-                 extension.descriptor.getLiteType(),
-                 false  /* isPacked */)) {
-      packed = false;  // Normal, unpacked value.
-    } else if (extension.descriptor.isRepeated &&
-               extension.descriptor.type.isPackable() &&
-               wireType == FieldSet.getWireFormatForFieldType(
-                 extension.descriptor.getLiteType(),
-                 true  /* isPacked */)) {
-      packed = true;  // Packed value.
-    } else {
-      unknown = true;  // Wrong wire type.
-    }
-
-    if (unknown) {  // Unknown field or wrong wire type.  Skip.
-      return unknownFields.mergeFieldFrom(tag, input);
-    }
-
-    if (packed) {
-      int length = input.readRawVarint32();
-      int limit = input.pushLimit(length);
-      if (extension.descriptor.getLiteType() == WireFormat.FieldType.ENUM) {
-        while (input.getBytesUntilLimit() > 0) {
-          int rawValue = input.readEnum();
-          Object value =
-              extension.descriptor.getEnumType().findValueByNumber(rawValue);
-          if (value == null) {
-            // If the number isn't recognized as a valid value for this
-            // enum, drop it (don't even add it to unknownFields).
-            return true;
-          }
-          extensions.addRepeatedField(extension.descriptor,
-                                      extension.singularToFieldSetType(value));
-        }
-      } else {
-        while (input.getBytesUntilLimit() > 0) {
-          Object value =
-              FieldSet.readPrimitiveField(input,
-                                          extension.descriptor.getLiteType(),
-                                          /*checkUtf8=*/ false);
-          extensions.addRepeatedField(extension.descriptor, value);
-        }
-      }
-      input.popLimit(limit);
-    } else {
-      Object value;
-      switch (extension.descriptor.getLiteJavaType()) {
-        case MESSAGE: {
-          MessageLite.Builder subBuilder = null;
-          if (!extension.descriptor.isRepeated()) {
-            MessageLite existingValue =
-                (MessageLite) extensions.getField(extension.descriptor);
-            if (existingValue != null) {
-              subBuilder = existingValue.toBuilder();
-            }
-          }
-          if (subBuilder == null) {
-            subBuilder = extension.getMessageDefaultInstance()
-                .newBuilderForType();
-          }
-          if (extension.descriptor.getLiteType() ==
-              WireFormat.FieldType.GROUP) {
-            input.readGroup(extension.getNumber(),
-                            subBuilder, extensionRegistry);
-          } else {
-            input.readMessage(subBuilder, extensionRegistry);
-          }
-          value = subBuilder.build();
-          break;
-        }
-        case ENUM:
-          int rawValue = input.readEnum();
-          value = extension.descriptor.getEnumType()
-                           .findValueByNumber(rawValue);
-          // If the number isn't recognized as a valid value for this enum,
-          // write it to unknown fields object.
-          if (value == null) {
-            unknownFields.mergeVarintField(fieldNumber, rawValue);
-            return true;
-          }
-          break;
-        default:
-          value = FieldSet.readPrimitiveField(input,
-              extension.descriptor.getLiteType(),
-              /*checkUtf8=*/ false);
-          break;
-      }
-
-      if (extension.descriptor.isRepeated()) {
-        extensions.addRepeatedField(extension.descriptor,
-                                    extension.singularToFieldSetType(value));
-      } else {
-        extensions.setField(extension.descriptor,
-                            extension.singularToFieldSetType(value));
-      }
-    }
-
-    return true;
-  }
-
   // -----------------------------------------------------------------
 
   /** For use by generated code only. */
@@ -893,7 +921,7 @@ public abstract class GeneratedMessageLite<
           extends ExtensionLite<ContainingType, Type> {
 
     /**
-     * Create a new isntance with the given parameters.
+     * Create a new instance with the given parameters.
      *
      * The last parameter {@code singularType} is only needed for enum types.
      * We store integer values for enum types in a {@link ExtendableMessage}
@@ -905,7 +933,7 @@ public abstract class GeneratedMessageLite<
         final Type defaultValue,
         final MessageLite messageDefaultInstance,
         final ExtensionDescriptor descriptor,
-        Class singularType) {
+        final Class singularType) {
       // Defensive checks to verify the correct initialization order of
       // GeneratedExtensions and their related GeneratedMessages.
       if (containingTypeDefaultInstance == null) {
@@ -921,24 +949,12 @@ public abstract class GeneratedMessageLite<
       this.defaultValue = defaultValue;
       this.messageDefaultInstance = messageDefaultInstance;
       this.descriptor = descriptor;
-
-      // Use Java reflection to invoke the static method {@code valueOf} of
-      // enum types in order to convert integers to concrete enum objects.
-      this.singularType = singularType;
-      if (Internal.EnumLite.class.isAssignableFrom(singularType)) {
-        this.enumValueOf = getMethodOrDie(
-            singularType, "valueOf", int.class);
-      } else {
-        this.enumValueOf = null;
-      }
     }
 
     final ContainingType containingTypeDefaultInstance;
     final Type defaultValue;
     final MessageLite messageDefaultInstance;
     final ExtensionDescriptor descriptor;
-    final Class singularType;
-    final Method enumValueOf;
 
     /**
      * Default instance of the type being extended, used to identify that type.
@@ -980,7 +996,7 @@ public abstract class GeneratedMessageLite<
 
     Object singularFromFieldSetType(final Object value) {
       if (descriptor.getLiteJavaType() == WireFormat.JavaType.ENUM) {
-        return invokeOrDie(enumValueOf, null, (Integer) value);
+        return descriptor.enumTypeMap.findValueByNumber((Integer) value);
       } else {
         return value;
       }
diff --git a/java/src/main/java/com/google/protobuf/TextFormat.java b/java/src/main/java/com/google/protobuf/TextFormat.java
index b4f4ce78..44d036c1 100644
--- a/java/src/main/java/com/google/protobuf/TextFormat.java
+++ b/java/src/main/java/com/google/protobuf/TextFormat.java
@@ -119,6 +119,21 @@ public final class TextFormat {
   }
 
   /**
+   * Generates a human readable form of the field, useful for debugging
+   * and other purposes, with no newline characters.
+   */
+  public static String shortDebugString(final FieldDescriptor field,
+                                        final Object value) {
+    try {
+      final StringBuilder sb = new StringBuilder();
+      SINGLE_LINE_PRINTER.printField(field, value, new TextGenerator(sb));
+      return sb.toString().trim();
+    } catch (IOException e) {
+        throw new IllegalStateException(e);
+    }
+  }
+
+  /**
    * Generates a human readable form of the unknown fields, useful for debugging
    * and other purposes, with no newline characters.
    */
diff --git a/java/src/main/java/com/google/protobuf/UnknownFieldSetLite.java b/java/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
index 45d5fc35..435ad4d4 100644
--- a/java/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
+++ b/java/src/main/java/com/google/protobuf/UnknownFieldSetLite.java
@@ -45,12 +45,13 @@ import java.util.Arrays;
  * @author dweis@google.com (Daniel Weis)
  */
 public final class UnknownFieldSetLite {
-
-  private static final int[] EMPTY_INT_ARRAY = new int[0];
-  private static final Object[] EMPTY_OBJECT_ARRAY = new Object[0];
+  
+  // Arbitrarily chosen.
+  // TODO(dweis): Tune this number?
+  private static final int MIN_CAPACITY = 8;
 
   private static final UnknownFieldSetLite DEFAULT_INSTANCE =
-      new UnknownFieldSetLite(0, EMPTY_INT_ARRAY, EMPTY_OBJECT_ARRAY);
+      new UnknownFieldSetLite(0, new int[0], new Object[0], false /* isMutable */);
 
   /**
    * Get an empty {@code UnknownFieldSetLite}.
@@ -62,25 +63,32 @@ public final class UnknownFieldSetLite {
   }
 
   /**
-   * Create a new {@link Builder}.
+   * Returns an empty {@code UnknownFieldSetLite.Builder}.
    *
    * <p>For use by generated code only.
    */
   public static Builder newBuilder() {
     return new Builder();
   }
+  
+  /**
+   * Returns a new mutable instance.
+   */
+  static UnknownFieldSetLite newInstance() {
+    return new UnknownFieldSetLite();
+  }
 
   /**
-   * Returns an {@code UnknownFieldSetLite} that is the composite of {@code first} and
+   * Returns a mutable {@code UnknownFieldSetLite} that is the composite of {@code first} and
    * {@code second}.
    */
-  static UnknownFieldSetLite concat(UnknownFieldSetLite first, UnknownFieldSetLite second) {
+  static UnknownFieldSetLite mutableCopyOf(UnknownFieldSetLite first, UnknownFieldSetLite second) {
     int count = first.count + second.count;
     int[] tags = Arrays.copyOf(first.tags, count);
     System.arraycopy(second.tags, 0, tags, first.count, second.count);
     Object[] objects = Arrays.copyOf(first.objects, count);
     System.arraycopy(second.objects, 0, objects, first.count, second.count);
-    return new UnknownFieldSetLite(count, tags, objects);
+    return new UnknownFieldSetLite(count, tags, objects, true /* isMutable */);
   }
   
   /**
@@ -102,14 +110,45 @@ public final class UnknownFieldSetLite {
    * The lazily computed serialized size of the set.
    */
   private int memoizedSerializedSize = -1;
+  
+  /**
+   * Indicates that this object is mutable. 
+   */
+  private boolean isMutable;
 
   /**
+   * Constructs a mutable {@code UnknownFieldSetLite}.
+   */
+  private UnknownFieldSetLite() {
+    this(0, new int[MIN_CAPACITY], new Object[MIN_CAPACITY], true /* isMutable */);
+  }
+  
+  /**
    * Constructs the {@code UnknownFieldSetLite}.
    */
-  private UnknownFieldSetLite(int count, int[] tags, Object[] objects) {
+  private UnknownFieldSetLite(int count, int[] tags, Object[] objects, boolean isMutable) {
     this.count = count;
     this.tags = tags;
     this.objects = objects;
+    this.isMutable = isMutable;
+  }
+  
+  /**
+   * Marks this object as immutable.
+   * 
+   * <p>Future calls to methods that attempt to modify this object will throw.
+   */
+  public void makeImmutable() {
+    this.isMutable = false;
+  }
+  
+  /**
+   * Throws an {@link UnsupportedOperationException} if immutable.
+   */
+  void checkMutable() {
+    if (!isMutable) {
+      throw new UnsupportedOperationException(); 
+    }
   }
 
   /**
@@ -223,6 +262,114 @@ public final class UnknownFieldSetLite {
     return hashCode;
   }
 
+  private void storeField(int tag, Object value) {
+    ensureCapacity();
+    
+    tags[count] = tag;
+    objects[count] = value;
+    count++;
+  }
+  
+  /**
+   * Ensures that our arrays are long enough to store more metadata.
+   */
+  private void ensureCapacity() {
+    if (count == tags.length) {        
+      int increment = count < (MIN_CAPACITY / 2) ? MIN_CAPACITY : count >> 1;
+      int newLength = count + increment;
+        
+      tags = Arrays.copyOf(tags, newLength);
+      objects = Arrays.copyOf(objects, newLength);
+    }
+  }
+  
+  /**
+   * Parse a single field from {@code input} and merge it into this set.
+   *
+   * <p>For use by generated code only.
+   *
+   * @param tag The field's tag number, which was already parsed.
+   * @return {@code false} if the tag is an end group tag.
+   */
+  boolean mergeFieldFrom(final int tag, final CodedInputStream input) throws IOException {
+    checkMutable();
+    final int fieldNumber = WireFormat.getTagFieldNumber(tag);
+    switch (WireFormat.getTagWireType(tag)) {
+      case WireFormat.WIRETYPE_VARINT:
+        storeField(tag, input.readInt64());
+        return true;
+      case WireFormat.WIRETYPE_FIXED32:
+        storeField(tag, input.readFixed32());
+        return true;
+      case WireFormat.WIRETYPE_FIXED64:
+        storeField(tag, input.readFixed64());
+        return true;
+      case WireFormat.WIRETYPE_LENGTH_DELIMITED:
+        storeField(tag, input.readBytes());
+        return true;
+      case WireFormat.WIRETYPE_START_GROUP:
+        final UnknownFieldSetLite subFieldSet = new UnknownFieldSetLite();
+        subFieldSet.mergeFrom(input);
+        input.checkLastTagWas(
+            WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_END_GROUP));
+        storeField(tag, subFieldSet);
+        return true;
+      case WireFormat.WIRETYPE_END_GROUP:
+        return false;
+      default:
+        throw InvalidProtocolBufferException.invalidWireType();
+    }
+  }
+
+  /**
+   * Convenience method for merging a new field containing a single varint
+   * value. This is used in particular when an unknown enum value is
+   * encountered.
+   *
+   * <p>For use by generated code only.
+   */
+  UnknownFieldSetLite mergeVarintField(int fieldNumber, int value) {
+    checkMutable();
+    if (fieldNumber == 0) {
+      throw new IllegalArgumentException("Zero is not a valid field number.");
+    }
+
+    storeField(WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_VARINT), (long) value);
+    
+    return this;
+  }
+
+  /**
+   * Convenience method for merging a length-delimited field.
+   *
+   * <p>For use by generated code only.
+   */
+  UnknownFieldSetLite mergeLengthDelimitedField(final int fieldNumber, final ByteString value) {  
+    checkMutable();
+    if (fieldNumber == 0) {
+      throw new IllegalArgumentException("Zero is not a valid field number.");
+    }
+
+    storeField(WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_LENGTH_DELIMITED), value);
+    
+    return this;
+  }
+  
+  /**
+   * Parse an entire message from {@code input} and merge its fields into
+   * this set.
+   */
+  private UnknownFieldSetLite mergeFrom(final CodedInputStream input) throws IOException {
+    // Ensures initialization in mergeFieldFrom.
+    while (true) {
+      final int tag = input.readTag();
+      if (tag == 0 || !mergeFieldFrom(tag, input)) {
+        break;
+      }
+    }
+    return this;
+  }
+  
   /**
    * Builder for {@link UnknownFieldSetLite}s.
    *
@@ -230,54 +377,27 @@ public final class UnknownFieldSetLite {
    *
    * <p>For use by generated code only.
    */
+  // TODO(dweis): Update the mutable API to no longer need this builder and delete.
   public static final class Builder {
-    
-    // Arbitrarily chosen.
-    // TODO(dweis): Tune this number?
-    private static final int MIN_CAPACITY = 8;
-    
-    private int count = 0;
-    private int[] tags = EMPTY_INT_ARRAY;
-    private Object[] objects = EMPTY_OBJECT_ARRAY;
 
-    private boolean built;
-
-    /**
-     * Constructs a {@code Builder}.
-     */
-    private Builder() {}
+    private UnknownFieldSetLite set;
+    
+    private Builder() {
+      this.set = null;
+    }
 
     /**
      * Ensures internal state is initialized for use.
      */
     private void ensureNotBuilt() {
-      if (built) {
-        throw new IllegalStateException("Do not reuse UnknownFieldSetLite Builders.");
+      if (set == null) {
+        set = new UnknownFieldSetLite();
       }
-    }
-    
-    private void storeField(int tag, Object value) {
-      ensureCapacity();
       
-      tags[count] = tag;
-      objects[count] = value;
-      count++;
+      set.checkMutable();
     }
     
     /**
-     * Ensures that our arrays are long enough to store more metadata.
-     */
-    private void ensureCapacity() {
-      if (count == tags.length) {        
-        int increment = count < (MIN_CAPACITY / 2) ? MIN_CAPACITY : count >> 1;
-        int newLength = count + increment;
-          
-        tags = Arrays.copyOf(tags, newLength);
-        objects = Arrays.copyOf(objects, newLength);
-      }
-    }
-
-    /**
      * Parse a single field from {@code input} and merge it into this set.
      *
      * <p>For use by generated code only.
@@ -285,36 +405,9 @@ public final class UnknownFieldSetLite {
      * @param tag The field's tag number, which was already parsed.
      * @return {@code false} if the tag is an end group tag.
      */
-    public boolean mergeFieldFrom(final int tag, final CodedInputStream input)
-                                  throws IOException {
+    boolean mergeFieldFrom(final int tag, final CodedInputStream input) throws IOException {
       ensureNotBuilt();
-
-      final int fieldNumber = WireFormat.getTagFieldNumber(tag);
-      switch (WireFormat.getTagWireType(tag)) {
-        case WireFormat.WIRETYPE_VARINT:
-          storeField(tag, input.readInt64());
-          return true;
-        case WireFormat.WIRETYPE_FIXED32:
-          storeField(tag, input.readFixed32());
-          return true;
-        case WireFormat.WIRETYPE_FIXED64:
-          storeField(tag, input.readFixed64());
-          return true;
-        case WireFormat.WIRETYPE_LENGTH_DELIMITED:
-          storeField(tag, input.readBytes());
-          return true;
-        case WireFormat.WIRETYPE_START_GROUP:
-          final Builder subBuilder = newBuilder();
-          subBuilder.mergeFrom(input);
-          input.checkLastTagWas(
-              WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_END_GROUP));
-          storeField(tag, subBuilder.build());
-          return true;
-        case WireFormat.WIRETYPE_END_GROUP:
-          return false;
-        default:
-          throw InvalidProtocolBufferException.invalidWireType();
-      }
+      return set.mergeFieldFrom(tag, input);
     }
 
     /**
@@ -324,71 +417,42 @@ public final class UnknownFieldSetLite {
      *
      * <p>For use by generated code only.
      */
-    public Builder mergeVarintField(int fieldNumber, int value) {
-      if (fieldNumber == 0) {
-        throw new IllegalArgumentException("Zero is not a valid field number.");
-      }
+    Builder mergeVarintField(int fieldNumber, int value) {
       ensureNotBuilt();
-
-      storeField(WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_VARINT), (long) value);
-      
+      set.mergeVarintField(fieldNumber, value);
       return this;
     }
-
+    
     /**
      * Convenience method for merging a length-delimited field.
      *
      * <p>For use by generated code only.
      */
-    public Builder mergeLengthDelimitedField(
-        final int fieldNumber, final ByteString value) {  
-      if (fieldNumber == 0) {
-        throw new IllegalArgumentException("Zero is not a valid field number.");
-      }
-      ensureNotBuilt();
-
-      storeField(WireFormat.makeTag(fieldNumber, WireFormat.WIRETYPE_LENGTH_DELIMITED), value);
-      
+    public Builder mergeLengthDelimitedField(final int fieldNumber, final ByteString value) {
+      ensureNotBuilt();  
+      set.mergeLengthDelimitedField(fieldNumber, value);
       return this;
     }
     
     /**
-     * Parse an entire message from {@code input} and merge its fields into
-     * this set.
-     */
-    private Builder mergeFrom(final CodedInputStream input) throws IOException {
-      // Ensures initialization in mergeFieldFrom.
-      while (true) {
-        final int tag = input.readTag();
-        if (tag == 0 || !mergeFieldFrom(tag, input)) {
-          break;
-        }
-      }
-      return this;
-    }
-
-    /**
      * Build the {@link UnknownFieldSetLite} and return it.
      *
      * <p>Once {@code build()} has been called, the {@code Builder} will no
      * longer be usable.  Calling any method after {@code build()} will result
-     * in undefined behavior and can cause a {@code IllegalStateException} to be
-     * thrown.
+     * in undefined behavior and can cause an
+     * {@code UnsupportedOperationException} to be thrown.
      *
      * <p>For use by generated code only.
      */
     public UnknownFieldSetLite build() {
-      if (built) {
-        throw new IllegalStateException("Do not reuse UnknownFieldSetLite Builders.");
-      }
-
-      built = true;
-      
-      if (count == 0) {
+      if (set == null) {
         return DEFAULT_INSTANCE;
       }
+      
+      set.checkMutable();
+      set.makeImmutable();
 
-      return new UnknownFieldSetLite(count, tags, objects);
+      return set;
     }
   }
 }
diff --git a/java/src/main/java/com/google/protobuf/Utf8.java b/java/src/main/java/com/google/protobuf/Utf8.java
index 0699778f..48c7e9e6 100644
--- a/java/src/main/java/com/google/protobuf/Utf8.java
+++ b/java/src/main/java/com/google/protobuf/Utf8.java
@@ -360,8 +360,8 @@ final class Utf8 {
   
   static class UnpairedSurrogateException extends IllegalArgumentException {
     
-    private UnpairedSurrogateException(int index) {
-      super("Unpaired surrogate at index " + index);
+    private UnpairedSurrogateException(int index, int length) {
+      super("Unpaired surrogate at index " + index + " of " + length);
     }
   }
   
@@ -417,7 +417,7 @@ final class Utf8 {
           // Check that we have a well-formed surrogate pair.
           int cp = Character.codePointAt(sequence, i);
           if (cp < Character.MIN_SUPPLEMENTARY_CODE_POINT) {
-            throw new UnpairedSurrogateException(i);
+            throw new UnpairedSurrogateException(i, utf16Length);
           }
           i++;
         }
@@ -457,7 +457,7 @@ final class Utf8 {
         final char low;
         if (i + 1 == sequence.length()
                 || !Character.isSurrogatePair(c, (low = sequence.charAt(++i)))) {
-          throw new UnpairedSurrogateException((i - 1));
+          throw new UnpairedSurrogateException((i - 1), utf16Length);
         }
         int codePoint = Character.toCodePoint(c, low);
         bytes[j++] = (byte) ((0xF << 4) | (codePoint >>> 18));
@@ -470,7 +470,7 @@ final class Utf8 {
         if ((Character.MIN_SURROGATE <= c && c <= Character.MAX_SURROGATE)
             && (i + 1 == sequence.length()
                 || !Character.isSurrogatePair(c, sequence.charAt(i + 1)))) {
-          throw new UnpairedSurrogateException(i);
+          throw new UnpairedSurrogateException(i, utf16Length);
         }
         throw new ArrayIndexOutOfBoundsException("Failed writing " + c + " at index " + j);
       }
diff --git a/java/src/test/java/com/google/protobuf/DescriptorsTest.java b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
index edd7fc46..30da2487 100644
--- a/java/src/test/java/com/google/protobuf/DescriptorsTest.java
+++ b/java/src/test/java/com/google/protobuf/DescriptorsTest.java
@@ -46,6 +46,7 @@ import com.google.protobuf.Descriptors.OneofDescriptor;
 import com.google.protobuf.Descriptors.ServiceDescriptor;
 import com.google.protobuf.test.UnittestImport;
 import com.google.protobuf.test.UnittestImport.ImportEnum;
+import com.google.protobuf.test.UnittestImport.ImportEnumForMap;
 import protobuf_unittest.TestCustomOptions;
 import protobuf_unittest.UnittestCustomOptions;
 import protobuf_unittest.UnittestProto;
@@ -115,7 +116,8 @@ public class DescriptorsTest extends TestCase {
     assertEquals(enumType, file.findEnumTypeByName("ForeignEnum"));
     assertNull(file.findEnumTypeByName("NoSuchType"));
     assertNull(file.findEnumTypeByName("protobuf_unittest.ForeignEnum"));
-    assertEquals(Arrays.asList(ImportEnum.getDescriptor()),
+    assertEquals(Arrays.asList(ImportEnum.getDescriptor(),
+                               ImportEnumForMap.getDescriptor()),
                  UnittestImport.getDescriptor().getEnumTypes());
     for (int i = 0; i < file.getEnumTypes().size(); i++) {
       assertEquals(i, file.getEnumTypes().get(i).getIndex());
diff --git a/java/src/test/java/com/google/protobuf/TextFormatTest.java b/java/src/test/java/com/google/protobuf/TextFormatTest.java
index 8294b865..1df4fad7 100644
--- a/java/src/test/java/com/google/protobuf/TextFormatTest.java
+++ b/java/src/test/java/com/google/protobuf/TextFormatTest.java
@@ -830,6 +830,22 @@ public class TextFormatTest extends TestCase {
             .build()));
   }
 
+  public void testShortDebugString_field() {
+    final FieldDescriptor dataField =
+      OneString.getDescriptor().findFieldByName("data");
+    assertEquals(
+      "data: \"test data\"",
+      TextFormat.shortDebugString(dataField, "test data"));
+
+    final FieldDescriptor optionalField =
+      TestAllTypes.getDescriptor().findFieldByName("optional_nested_message");
+    final Object value = NestedMessage.newBuilder().setBb(42).build();
+
+    assertEquals(
+      "optional_nested_message { bb: 42 }",
+      TextFormat.shortDebugString(optionalField, value));
+  }
+
   public void testShortDebugString_unknown() {
     assertEquals("5: 1 5: 0x00000002 5: 0x0000000000000003 5: \"4\" 5 { 10: 5 }"
         + " 8: 1 8: 2 8: 3 15: 12379813812177893520 15: 0xabcd1234 15:"
diff --git a/java/src/test/java/com/google/protobuf/UnknownFieldSetLiteTest.java b/java/src/test/java/com/google/protobuf/UnknownFieldSetLiteTest.java
index e76b4a67..dc987379 100644
--- a/java/src/test/java/com/google/protobuf/UnknownFieldSetLiteTest.java
+++ b/java/src/test/java/com/google/protobuf/UnknownFieldSetLiteTest.java
@@ -30,6 +30,8 @@
 
 package com.google.protobuf;
 
+import com.google.protobuf.UnittestLite.TestAllExtensionsLite;
+import com.google.protobuf.UnittestLite.TestAllTypesLite;
 import protobuf_unittest.lite_equals_and_hash.LiteEqualsAndHash;
 import protobuf_unittest.lite_equals_and_hash.LiteEqualsAndHash.Bar;
 import protobuf_unittest.lite_equals_and_hash.LiteEqualsAndHash.Foo;
@@ -52,7 +54,40 @@ public class UnknownFieldSetLiteTest extends TestCase {
         UnknownFieldSetLite.newBuilder()
             .build());
   }
+  
+  public void testBuilderReuse() throws IOException {
+    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
+    builder.mergeVarintField(10, 2);
+    builder.build();
+
+    try {
+      builder.build();
+      fail();
+    } catch (UnsupportedOperationException e) {
+      // Expected.
+    }
+
+    try {
+      builder.mergeFieldFrom(0, CodedInputStream.newInstance(new byte[0]));
+      fail();
+    } catch (UnsupportedOperationException e) {
+      // Expected.
+    }
+
+    try {
+      builder.mergeVarintField(5, 1);
+      fail();
+    } catch (UnsupportedOperationException e) {
+      // Expected.
+    }
+  }
 
+  public void testBuilderReuse_empty() {
+    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
+    builder.build();
+    builder.build();
+  }
+  
   public void testDefaultInstance() {
     UnknownFieldSetLite unknownFields = UnknownFieldSetLite.getDefaultInstance();
 
@@ -67,10 +102,10 @@ public class UnknownFieldSetLiteTest extends TestCase {
 
     CodedInputStream input = CodedInputStream.newInstance(foo.toByteArray());
 
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.mergeFieldFrom(input.readTag(), input);
+    UnknownFieldSetLite instance = UnknownFieldSetLite.newInstance();
+    instance.mergeFieldFrom(input.readTag(), input);
 
-    assertEquals(foo.toByteString(), toByteString(builder.build()));
+    assertEquals(foo.toByteString(), toByteString(instance));
   }
 
   public void testSerializedSize() throws IOException {
@@ -80,18 +115,18 @@ public class UnknownFieldSetLiteTest extends TestCase {
 
     CodedInputStream input = CodedInputStream.newInstance(foo.toByteArray());
 
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.mergeFieldFrom(input.readTag(), input);
+    UnknownFieldSetLite instance = UnknownFieldSetLite.newInstance();
+    instance.mergeFieldFrom(input.readTag(), input);
 
-    assertEquals(foo.toByteString().size(), builder.build().getSerializedSize());
+    assertEquals(foo.toByteString().size(), instance.getSerializedSize());
   }
 
   public void testMergeVarintField() throws IOException {
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.mergeVarintField(10, 2);
+    UnknownFieldSetLite unknownFields = UnknownFieldSetLite.newInstance();
+    unknownFields.mergeVarintField(10, 2);
 
     CodedInputStream input =
-        CodedInputStream.newInstance(toByteString(builder.build()).toByteArray());
+        CodedInputStream.newInstance(toByteString(unknownFields).toByteArray());
 
     int tag = input.readTag();
     assertEquals(10, WireFormat.getTagFieldNumber(tag));
@@ -101,11 +136,11 @@ public class UnknownFieldSetLiteTest extends TestCase {
   }
 
   public void testMergeVarintField_negative() throws IOException {
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
+    UnknownFieldSetLite builder = UnknownFieldSetLite.newInstance();
     builder.mergeVarintField(10, -6);
 
     CodedInputStream input =
-        CodedInputStream.newInstance(toByteString(builder.build()).toByteArray());
+        CodedInputStream.newInstance(toByteString(builder).toByteArray());
 
     int tag = input.readTag();
     assertEquals(10, WireFormat.getTagFieldNumber(tag));
@@ -115,13 +150,11 @@ public class UnknownFieldSetLiteTest extends TestCase {
   }
 
   public void testEqualsAndHashCode() {
-    UnknownFieldSetLite.Builder builder1 = UnknownFieldSetLite.newBuilder();
-    builder1.mergeVarintField(10, 2);
-    UnknownFieldSetLite unknownFields1 = builder1.build();
+    UnknownFieldSetLite unknownFields1 = UnknownFieldSetLite.newInstance();
+    unknownFields1.mergeVarintField(10, 2);
 
-    UnknownFieldSetLite.Builder builder2 = UnknownFieldSetLite.newBuilder();
-    builder2.mergeVarintField(10, 2);
-    UnknownFieldSetLite unknownFields2 = builder2.build();
+    UnknownFieldSetLite unknownFields2 = UnknownFieldSetLite.newInstance();
+    unknownFields2.mergeVarintField(10, 2);
 
     assertEquals(unknownFields1, unknownFields2);
     assertEquals(unknownFields1.hashCode(), unknownFields2.hashCode());
@@ -129,12 +162,11 @@ public class UnknownFieldSetLiteTest extends TestCase {
     assertFalse(unknownFields1.hashCode() == UnknownFieldSetLite.getDefaultInstance().hashCode());
   }
 
-  public void testConcat() throws IOException {
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.mergeVarintField(10, 2);
-    UnknownFieldSetLite unknownFields = builder.build();
-
-    unknownFields = UnknownFieldSetLite.concat(unknownFields, unknownFields);
+  public void testMutableCopyOf() throws IOException {
+    UnknownFieldSetLite unknownFields = UnknownFieldSetLite.newInstance();
+    unknownFields.mergeVarintField(10, 2);
+    unknownFields = UnknownFieldSetLite.mutableCopyOf(unknownFields, unknownFields);
+    unknownFields.checkMutable();
 
     CodedInputStream input =
         CodedInputStream.newInstance(toByteString(unknownFields).toByteArray());
@@ -151,53 +183,15 @@ public class UnknownFieldSetLiteTest extends TestCase {
     assertTrue(input.isAtEnd());
   }
 
-  public void testConcat_empty() {
-    UnknownFieldSetLite unknownFields = UnknownFieldSetLite.concat(
+  public void testMutableCopyOf_empty() {
+    UnknownFieldSetLite unknownFields = UnknownFieldSetLite.mutableCopyOf(
         UnknownFieldSetLite.getDefaultInstance(), UnknownFieldSetLite.getDefaultInstance());
+    unknownFields.checkMutable();
 
     assertEquals(0, unknownFields.getSerializedSize());
     assertEquals(ByteString.EMPTY, toByteString(unknownFields));
   }
 
-  public void testBuilderReuse() throws IOException {
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.mergeVarintField(10, 2);
-    builder.build();
-
-    try {
-      builder.build();
-      fail();
-    } catch (IllegalStateException e) {
-      // Expected.
-    }
-
-    try {
-      builder.mergeFieldFrom(0, CodedInputStream.newInstance(new byte[0]));
-      fail();
-    } catch (IllegalStateException e) {
-      // Expected.
-    }
-
-    try {
-      builder.mergeVarintField(5, 1);
-      fail();
-    } catch (IllegalStateException e) {
-      // Expected.
-    }
-  }
-
-  public void testBuilderReuse_empty() {
-    UnknownFieldSetLite.Builder builder = UnknownFieldSetLite.newBuilder();
-    builder.build();
-
-    try {
-      builder.build();
-      fail();
-    } catch (IllegalStateException e) {
-      // Expected.
-    }
-  }
-
   public void testRoundTrips() throws InvalidProtocolBufferException {
     Foo foo = Foo.newBuilder()
         .setValue(1)
@@ -301,6 +295,64 @@ public class UnknownFieldSetLiteTest extends TestCase {
       // Expected.
     }
   }
+  
+  public void testMakeImmutable() throws Exception {
+    UnknownFieldSetLite unknownFields = UnknownFieldSetLite.newInstance();
+    unknownFields.makeImmutable();
+    
+    try {
+      unknownFields.mergeVarintField(1, 1);
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    try {
+      unknownFields.mergeLengthDelimitedField(2, ByteString.copyFromUtf8("hello"));
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    try {
+      unknownFields.mergeFieldFrom(1, CodedInputStream.newInstance(new byte[0]));
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+  }
+  
+  public void testEndToEnd() throws Exception {
+    TestAllTypesLite testAllTypes = TestAllTypesLite.getDefaultInstance();
+    try {
+      testAllTypes.unknownFields.checkMutable();
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    testAllTypes = TestAllTypesLite.parseFrom(new byte[0]);
+    try {
+      testAllTypes.unknownFields.checkMutable();
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    testAllTypes = TestAllTypesLite.newBuilder().build();
+    try {
+      testAllTypes.unknownFields.checkMutable();
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    testAllTypes = TestAllTypesLite.newBuilder()
+        .setDefaultBool(true)
+        .build();
+    try {
+      testAllTypes.unknownFields.checkMutable();
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+    
+    TestAllExtensionsLite testAllExtensions = TestAllExtensionsLite.newBuilder()
+        .mergeFrom(TestAllExtensionsLite.newBuilder()
+            .setExtension(UnittestLite.optionalInt32ExtensionLite, 2)
+            .build().toByteArray())
+        .build();
+    try {
+      testAllExtensions.unknownFields.checkMutable();
+      fail();
+    } catch (UnsupportedOperationException expected) {}
+  }
 
   private ByteString toByteString(UnknownFieldSetLite unknownFields) {
     ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
diff --git a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
index dc082615..8c37c03c 100644
--- a/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
+++ b/java/src/test/java/com/google/protobuf/test_bad_identifiers.proto
@@ -140,11 +140,11 @@ message TestConflictingFieldNames {
   optional bytes bytes_field_count = 14;
   optional TestMessage message_field_count = 15;
 
-  repeated int32 Int32Field = 21;
-  repeated TestEnum EnumField = 22;
-  repeated string StringField = 23;
-  repeated bytes BytesField = 24;
-  repeated TestMessage MessageField = 25;
+  repeated int32 Int32Field = 21;  // NO_PROTO3
+  repeated TestEnum EnumField = 22;  // NO_PROTO3
+  repeated string StringField = 23;  // NO_PROTO3
+  repeated bytes BytesField = 24;  // NO_PROTO3
+  repeated TestMessage MessageField = 25;  // NO_PROTO3
 
   // This field conflicts with "int32_field" as they both generate
   // the method getInt32FieldList().
diff --git a/java/util/pom.xml b/java/util/pom.xml
index 44a5662d..9416f380 100644
--- a/java/util/pom.xml
+++ b/java/util/pom.xml
@@ -10,7 +10,7 @@
   </parent>
   <groupId>com.google.protobuf</groupId>
   <artifactId>protobuf-java-util</artifactId>
-  <version>3.0.0-beta-1</version>
+  <version>3.0.0-alpha-4-pre</version>
   <packaging>bundle</packaging>
   <name>Protocol Buffer Java API</name>
   <description>
@@ -36,7 +36,7 @@
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>
-      <version>3.0.0-beta-1</version>
+      <version>3.0.0-alpha-4-pre</version>
       <scope>compile</scope>
     </dependency>
     <dependency>
@@ -123,7 +123,7 @@
           <instructions>
             <Bundle-DocURL>https://developers.google.com/protocol-buffers/</Bundle-DocURL>
             <Bundle-SymbolicName>com.google.protobuf.util</Bundle-SymbolicName>
-            <Export-Package>com.google.protobuf.util;version=3.0.0-beta-1</Export-Package>
+            <Export-Package>com.google.protobuf.util;version=3.0.0-alpha-3</Export-Package>
           </instructions>
         </configuration>
       </plugin>
diff --git a/python/google/protobuf/descriptor.py b/python/google/protobuf/descriptor.py
index 95b703fc..2bf36532 100755
--- a/python/google/protobuf/descriptor.py
+++ b/python/google/protobuf/descriptor.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2007 Google Inc. All Rights Reserved.
-
 """Descriptors essentially contain exactly the information found in a .proto
 file, in types that make this information accessible in Python.
 """
@@ -40,7 +38,6 @@ import six
 
 from google.protobuf.internal import api_implementation
 
-
 _USE_C_DESCRIPTORS = False
 if api_implementation.Type() == 'cpp':
   # Used by MakeDescriptor in cpp mode
@@ -221,6 +218,9 @@ class Descriptor(_NestedDescriptorBase):
     fields_by_name: (dict str -> FieldDescriptor) Same FieldDescriptor
       objects as in |fields|, but indexed by "name" attribute in each
       FieldDescriptor.
+    fields_by_camelcase_name: (dict str -> FieldDescriptor) Same
+      FieldDescriptor objects as in |fields|, but indexed by
+      "camelcase_name" attribute in each FieldDescriptor.
 
     nested_types: (list of Descriptors) Descriptor references
       for all protocol message types nested within this one.
@@ -292,6 +292,7 @@ class Descriptor(_NestedDescriptorBase):
       field.containing_type = self
     self.fields_by_number = dict((f.number, f) for f in fields)
     self.fields_by_name = dict((f.name, f) for f in fields)
+    self._fields_by_camelcase_name = None
 
     self.nested_types = nested_types
     for nested_type in nested_types:
@@ -317,6 +318,13 @@ class Descriptor(_NestedDescriptorBase):
       oneof.containing_type = self
     self.syntax = syntax or "proto2"
 
+  @property
+  def fields_by_camelcase_name(self):
+    if self._fields_by_camelcase_name is None:
+      self._fields_by_camelcase_name = dict(
+          (f.camelcase_name, f) for f in self.fields)
+    return self._fields_by_camelcase_name
+
   def EnumValueName(self, enum, value):
     """Returns the string name of an enum value.
 
@@ -365,6 +373,7 @@ class FieldDescriptor(DescriptorBase):
     name: (str) Name of this field, exactly as it appears in .proto.
     full_name: (str) Name of this field, including containing scope.  This is
       particularly relevant for extensions.
+    camelcase_name: (str) Camelcase name of this field.
     index: (int) Dense, 0-indexed index giving the order that this
       field textually appears within its message in the .proto file.
     number: (int) Tag number declared for this field in the .proto file.
@@ -509,6 +518,7 @@ class FieldDescriptor(DescriptorBase):
     super(FieldDescriptor, self).__init__(options, 'FieldOptions')
     self.name = name
     self.full_name = full_name
+    self._camelcase_name = None
     self.index = index
     self.number = number
     self.type = type
@@ -530,6 +540,12 @@ class FieldDescriptor(DescriptorBase):
     else:
       self._cdescriptor = None
 
+  @property
+  def camelcase_name(self):
+    if self._camelcase_name is None:
+      self._camelcase_name = _ToCamelCase(self.name)
+    return self._camelcase_name
+
   @staticmethod
   def ProtoTypeToCppProtoType(proto_type):
     """Converts from a Python proto type to a C++ Proto Type.
@@ -822,6 +838,27 @@ def _ParseOptions(message, string):
   return message
 
 
+def _ToCamelCase(name):
+  """Converts name to camel-case and returns it."""
+  capitalize_next = False
+  result = []
+
+  for c in name:
+    if c == '_':
+      if result:
+        capitalize_next = True
+    elif capitalize_next:
+      result.append(c.upper())
+      capitalize_next = False
+    else:
+      result += c
+
+  # Lower-case the first letter.
+  if result and result[0].isupper():
+    result[0] = result[0].lower()
+  return ''.join(result)
+
+
 def MakeDescriptor(desc_proto, package='', build_file_if_cpp=True,
                    syntax=None):
   """Make a protobuf Descriptor given a DescriptorProto protobuf.
diff --git a/python/google/protobuf/internal/decoder.py b/python/google/protobuf/internal/decoder.py
index 4fd7a864..31869e45 100755
--- a/python/google/protobuf/internal/decoder.py
+++ b/python/google/protobuf/internal/decoder.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2009 Google Inc. All Rights Reserved.
-
 """Code for decoding protocol buffer primitives.
 
 This code is very similar to encoder.py -- read the docs for that module first.
diff --git a/python/google/protobuf/internal/descriptor_database_test.py b/python/google/protobuf/internal/descriptor_database_test.py
index 1baff7d1..3241cb72 100644
--- a/python/google/protobuf/internal/descriptor_database_test.py
+++ b/python/google/protobuf/internal/descriptor_database_test.py
@@ -34,10 +34,7 @@
 
 __author__ = 'matthewtoia@google.com (Matt Toia)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import descriptor_pb2
 from google.protobuf.internal import factory_test2_pb2
 from google.protobuf import descriptor_database
diff --git a/python/google/protobuf/internal/descriptor_pool_test.py b/python/google/protobuf/internal/descriptor_pool_test.py
index 2a482fba..6bbc8233 100644
--- a/python/google/protobuf/internal/descriptor_pool_test.py
+++ b/python/google/protobuf/internal/descriptor_pool_test.py
@@ -35,11 +35,8 @@
 __author__ = 'matthewtoia@google.com (Matt Toia)'
 
 import os
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
 
+import unittest
 from google.protobuf import unittest_pb2
 from google.protobuf import descriptor_pb2
 from google.protobuf.internal import api_implementation
@@ -47,6 +44,7 @@ from google.protobuf.internal import descriptor_pool_test1_pb2
 from google.protobuf.internal import descriptor_pool_test2_pb2
 from google.protobuf.internal import factory_test1_pb2
 from google.protobuf.internal import factory_test2_pb2
+from google.protobuf.internal import test_util
 from google.protobuf import descriptor
 from google.protobuf import descriptor_database
 from google.protobuf import descriptor_pool
diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index 34843a61..f94f9f14 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -1,4 +1,4 @@
-#! /usr/bin/python
+#! /usr/bin/env python
 #
 # Protocol Buffers - Google's data interchange format
 # Copyright 2008 Google Inc.  All rights reserved.
@@ -36,20 +36,17 @@ __author__ = 'robinson@google.com (Will Robinson)'
 
 import sys
 
+import unittest
 from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import descriptor_pb2
 from google.protobuf.internal import api_implementation
+from google.protobuf.internal import test_util
 from google.protobuf import descriptor
 from google.protobuf import symbol_database
 from google.protobuf import text_format
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
-
 
 TEST_EMPTY_MESSAGE_DESCRIPTOR_ASCII = """
 name: 'TestEmptyMessage'
@@ -394,7 +391,7 @@ class DescriptorTest(unittest.TestCase):
     self.assertEqual(self.my_file.name, 'some/filename/some.proto')
     self.assertEqual(self.my_file.package, 'protobuf_unittest')
 
-  @unittest.skipIf(
+  @test_util.skipIf(
       api_implementation.Type() != 'cpp' or api_implementation.Version() != 2,
       'Immutability of descriptors is only enforced in v2 implementation')
   def testImmutableCppDescriptor(self):
@@ -425,10 +422,12 @@ class GeneratedDescriptorTest(unittest.TestCase):
     self.CheckDescriptorSequence(message_descriptor.fields)
     self.CheckDescriptorMapping(message_descriptor.fields_by_name)
     self.CheckDescriptorMapping(message_descriptor.fields_by_number)
+    self.CheckDescriptorMapping(message_descriptor.fields_by_camelcase_name)
 
   def CheckFieldDescriptor(self, field_descriptor):
     # Basic properties
     self.assertEqual(field_descriptor.name, 'optional_int32')
+    self.assertEqual(field_descriptor.camelcase_name, 'optionalInt32')
     self.assertEqual(field_descriptor.full_name,
                      'protobuf_unittest.TestAllTypes.optional_int32')
     self.assertEqual(field_descriptor.containing_type.name, 'TestAllTypes')
@@ -437,6 +436,10 @@ class GeneratedDescriptorTest(unittest.TestCase):
     self.assertEqual(
         field_descriptor.containing_type.fields_by_name['optional_int32'],
         field_descriptor)
+    self.assertEqual(
+        field_descriptor.containing_type.fields_by_camelcase_name[
+            'optionalInt32'],
+        field_descriptor)
     self.assertIn(field_descriptor, [field_descriptor])
     self.assertIn(field_descriptor, {field_descriptor: None})
 
@@ -481,6 +484,9 @@ class GeneratedDescriptorTest(unittest.TestCase):
     self.CheckMessageDescriptor(message_descriptor)
     field_descriptor = message_descriptor.fields_by_name['optional_int32']
     self.CheckFieldDescriptor(field_descriptor)
+    field_descriptor = message_descriptor.fields_by_camelcase_name[
+        'optionalInt32']
+    self.CheckFieldDescriptor(field_descriptor)
 
   def testCppDescriptorContainer(self):
     # Check that the collection is still valid even if the parent disappeared.
@@ -779,5 +785,20 @@ class MakeDescriptorTest(unittest.TestCase):
     self.assertEqual(101,
                       options.Extensions[unittest_custom_options_pb2.msgopt].i)
 
+  def testCamelcaseName(self):
+    descriptor_proto = descriptor_pb2.DescriptorProto()
+    descriptor_proto.name = 'Bar'
+    names = ['foo_foo', 'FooBar', 'fooBaz', 'fooFoo', 'foobar']
+    camelcase_names = ['fooFoo', 'fooBar', 'fooBaz', 'fooFoo', 'foobar']
+    for index in range(len(names)):
+      field = descriptor_proto.field.add()
+      field.number = index + 1
+      field.name = names[index]
+    result = descriptor.MakeDescriptor(descriptor_proto)
+    for index in range(len(camelcase_names)):
+      self.assertEqual(result.fields[index].camelcase_name,
+                       camelcase_names[index])
+
+
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/encoder.py b/python/google/protobuf/internal/encoder.py
index d72cd29d..48ef2df3 100755
--- a/python/google/protobuf/internal/encoder.py
+++ b/python/google/protobuf/internal/encoder.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2009 Google Inc. All Rights Reserved.
-
 """Code for encoding protocol message primitives.
 
 Contains the logic for encoding every logical protocol field type
diff --git a/python/google/protobuf/internal/generator_test.py b/python/google/protobuf/internal/generator_test.py
index 9956da59..7fcb1377 100755
--- a/python/google/protobuf/internal/generator_test.py
+++ b/python/google/protobuf/internal/generator_test.py
@@ -41,10 +41,7 @@ further ensures that we can use Python protocol message objects as we expect.
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf.internal import test_bad_identifiers_pb2
 from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_import_pb2
diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
new file mode 100644
index 00000000..6d0071be
--- /dev/null
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -0,0 +1,522 @@
+#! /usr/bin/env python
+#
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Test for google.protobuf.json_format."""
+
+__author__ = 'jieluo@google.com (Jie Luo)'
+
+import json
+import math
+import sys
+
+import unittest
+from google.protobuf import json_format
+from google.protobuf.util import json_format_proto3_pb2
+
+
+class JsonFormatBase(unittest.TestCase):
+
+  def FillAllFields(self, message):
+    message.int32_value = 20
+    message.int64_value = -20
+    message.uint32_value = 3120987654
+    message.uint64_value = 12345678900
+    message.float_value = float('-inf')
+    message.double_value = 3.1415
+    message.bool_value = True
+    message.string_value = 'foo'
+    message.bytes_value = b'bar'
+    message.message_value.value = 10
+    message.enum_value = json_format_proto3_pb2.BAR
+    # Repeated
+    message.repeated_int32_value.append(0x7FFFFFFF)
+    message.repeated_int32_value.append(-2147483648)
+    message.repeated_int64_value.append(9007199254740992)
+    message.repeated_int64_value.append(-9007199254740992)
+    message.repeated_uint32_value.append(0xFFFFFFF)
+    message.repeated_uint32_value.append(0x7FFFFFF)
+    message.repeated_uint64_value.append(9007199254740992)
+    message.repeated_uint64_value.append(9007199254740991)
+    message.repeated_float_value.append(0)
+
+    message.repeated_double_value.append(1E-15)
+    message.repeated_double_value.append(float('inf'))
+    message.repeated_bool_value.append(True)
+    message.repeated_bool_value.append(False)
+    message.repeated_string_value.append('Few symbols!#$,;')
+    message.repeated_string_value.append('bar')
+    message.repeated_bytes_value.append(b'foo')
+    message.repeated_bytes_value.append(b'bar')
+    message.repeated_message_value.add().value = 10
+    message.repeated_message_value.add().value = 11
+    message.repeated_enum_value.append(json_format_proto3_pb2.FOO)
+    message.repeated_enum_value.append(json_format_proto3_pb2.BAR)
+    self.message = message
+
+  def CheckParseBack(self, message, parsed_message):
+    json_format.Parse(json_format.MessageToJson(message),
+                      parsed_message)
+    self.assertEqual(message, parsed_message)
+
+  def CheckError(self, text, error_message):
+    message = json_format_proto3_pb2.TestMessage()
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        error_message,
+        json_format.Parse, text, message)
+
+
+class JsonFormatTest(JsonFormatBase):
+
+  def testEmptyMessageToJson(self):
+    message = json_format_proto3_pb2.TestMessage()
+    self.assertEqual(json_format.MessageToJson(message),
+                     '{}')
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    self.CheckParseBack(message, parsed_message)
+
+  def testPartialMessageToJson(self):
+    message = json_format_proto3_pb2.TestMessage(
+        string_value='test',
+        repeated_int32_value=[89, 4])
+    self.assertEqual(json.loads(json_format.MessageToJson(message)),
+                     json.loads('{"stringValue": "test", '
+                                '"repeatedInt32Value": [89, 4]}'))
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    self.CheckParseBack(message, parsed_message)
+
+  def testAllFieldsToJson(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = ('{"int32Value": 20, '
+            '"int64Value": "-20", '
+            '"uint32Value": 3120987654,'
+            '"uint64Value": "12345678900",'
+            '"floatValue": "-Infinity",'
+            '"doubleValue": 3.1415,'
+            '"boolValue": true,'
+            '"stringValue": "foo",'
+            '"bytesValue": "YmFy",'
+            '"messageValue": {"value": 10},'
+            '"enumValue": "BAR",'
+            '"repeatedInt32Value": [2147483647, -2147483648],'
+            '"repeatedInt64Value": ["9007199254740992", "-9007199254740992"],'
+            '"repeatedUint32Value": [268435455, 134217727],'
+            '"repeatedUint64Value": ["9007199254740992", "9007199254740991"],'
+            '"repeatedFloatValue": [0],'
+            '"repeatedDoubleValue": [1e-15, "Infinity"],'
+            '"repeatedBoolValue": [true, false],'
+            '"repeatedStringValue": ["Few symbols!#$,;", "bar"],'
+            '"repeatedBytesValue": ["Zm9v", "YmFy"],'
+            '"repeatedMessageValue": [{"value": 10}, {"value": 11}],'
+            '"repeatedEnumValue": ["FOO", "BAR"]'
+            '}')
+    self.FillAllFields(message)
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message)),
+        json.loads(text))
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    json_format.Parse(text, parsed_message)
+    self.assertEqual(message, parsed_message)
+
+  def testJsonEscapeString(self):
+    message = json_format_proto3_pb2.TestMessage()
+    if sys.version_info[0] < 3:
+      message.string_value = '&\n<\"\r>\b\t\f\\\001/\xe2\x80\xa8\xe2\x80\xa9'
+    else:
+      message.string_value = '&\n<\"\r>\b\t\f\\\001/'
+      message.string_value += (b'\xe2\x80\xa8\xe2\x80\xa9').decode('utf-8')
+    self.assertEqual(
+        json_format.MessageToJson(message),
+        '{\n  "stringValue": '
+        '"&\\n<\\\"\\r>\\b\\t\\f\\\\\\u0001/\\u2028\\u2029"\n}')
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    self.CheckParseBack(message, parsed_message)
+    text = u'{"int32Value": "\u0031"}'
+    json_format.Parse(text, message)
+    self.assertEqual(message.int32_value, 1)
+
+  def testAlwaysSeriliaze(self):
+    message = json_format_proto3_pb2.TestMessage(
+        string_value='foo')
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message, True)),
+        json.loads('{'
+                   '"repeatedStringValue": [],'
+                   '"stringValue": "foo",'
+                   '"repeatedBoolValue": [],'
+                   '"repeatedUint32Value": [],'
+                   '"repeatedInt32Value": [],'
+                   '"enumValue": "FOO",'
+                   '"int32Value": 0,'
+                   '"floatValue": 0,'
+                   '"int64Value": "0",'
+                   '"uint32Value": 0,'
+                   '"repeatedBytesValue": [],'
+                   '"repeatedUint64Value": [],'
+                   '"repeatedDoubleValue": [],'
+                   '"bytesValue": "",'
+                   '"boolValue": false,'
+                   '"repeatedEnumValue": [],'
+                   '"uint64Value": "0",'
+                   '"doubleValue": 0,'
+                   '"repeatedFloatValue": [],'
+                   '"repeatedInt64Value": [],'
+                   '"repeatedMessageValue": []}'))
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    self.CheckParseBack(message, parsed_message)
+
+  def testMapFields(self):
+    message = json_format_proto3_pb2.TestMap()
+    message.bool_map[True] = 1
+    message.bool_map[False] = 2
+    message.int32_map[1] = 2
+    message.int32_map[2] = 3
+    message.int64_map[1] = 2
+    message.int64_map[2] = 3
+    message.uint32_map[1] = 2
+    message.uint32_map[2] = 3
+    message.uint64_map[1] = 2
+    message.uint64_map[2] = 3
+    message.string_map['1'] = 2
+    message.string_map['null'] = 3
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message, True)),
+        json.loads('{'
+                   '"boolMap": {"false": 2, "true": 1},'
+                   '"int32Map": {"1": 2, "2": 3},'
+                   '"int64Map": {"1": 2, "2": 3},'
+                   '"uint32Map": {"1": 2, "2": 3},'
+                   '"uint64Map": {"1": 2, "2": 3},'
+                   '"stringMap": {"1": 2, "null": 3}'
+                   '}'))
+    parsed_message = json_format_proto3_pb2.TestMap()
+    self.CheckParseBack(message, parsed_message)
+
+  def testOneofFields(self):
+    message = json_format_proto3_pb2.TestOneof()
+    # Always print does not affect oneof fields.
+    self.assertEqual(
+        json_format.MessageToJson(message, True),
+        '{}')
+    message.oneof_int32_value = 0
+    self.assertEqual(
+        json_format.MessageToJson(message, True),
+        '{\n'
+        '  "oneofInt32Value": 0\n'
+        '}')
+    parsed_message = json_format_proto3_pb2.TestOneof()
+    self.CheckParseBack(message, parsed_message)
+
+  def testTimestampMessage(self):
+    message = json_format_proto3_pb2.TestTimestamp()
+    message.value.seconds = 0
+    message.value.nanos = 0
+    message.repeated_value.add().seconds = 20
+    message.repeated_value[0].nanos = 1
+    message.repeated_value.add().seconds = 0
+    message.repeated_value[1].nanos = 10000
+    message.repeated_value.add().seconds = 100000000
+    message.repeated_value[2].nanos = 0
+    # Maximum time
+    message.repeated_value.add().seconds = 253402300799
+    message.repeated_value[3].nanos = 999999999
+    # Minimum time
+    message.repeated_value.add().seconds = -62135596800
+    message.repeated_value[4].nanos = 0
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message, True)),
+        json.loads('{'
+                   '"value": "1970-01-01T00:00:00Z",'
+                   '"repeatedValue": ['
+                   '  "1970-01-01T00:00:20.000000001Z",'
+                   '  "1970-01-01T00:00:00.000010Z",'
+                   '  "1973-03-03T09:46:40Z",'
+                   '  "9999-12-31T23:59:59.999999999Z",'
+                   '  "0001-01-01T00:00:00Z"'
+                   ']'
+                   '}'))
+    parsed_message = json_format_proto3_pb2.TestTimestamp()
+    self.CheckParseBack(message, parsed_message)
+    text = (r'{"value": "1972-01-01T01:00:00.01+08:00",'
+            r'"repeatedValue":['
+            r'  "1972-01-01T01:00:00.01+08:30",'
+            r'  "1972-01-01T01:00:00.01-01:23"]}')
+    json_format.Parse(text, parsed_message)
+    self.assertEqual(parsed_message.value.seconds, 63104400)
+    self.assertEqual(parsed_message.value.nanos, 10000000)
+    self.assertEqual(parsed_message.repeated_value[0].seconds, 63106200)
+    self.assertEqual(parsed_message.repeated_value[1].seconds, 63070620)
+
+  def testDurationMessage(self):
+    message = json_format_proto3_pb2.TestDuration()
+    message.value.seconds = 1
+    message.repeated_value.add().seconds = 0
+    message.repeated_value[0].nanos = 10
+    message.repeated_value.add().seconds = -1
+    message.repeated_value[1].nanos = -1000
+    message.repeated_value.add().seconds = 10
+    message.repeated_value[2].nanos = 11000000
+    message.repeated_value.add().seconds = -315576000000
+    message.repeated_value.add().seconds = 315576000000
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message, True)),
+        json.loads('{'
+                   '"value": "1s",'
+                   '"repeatedValue": ['
+                   '  "0.000000010s",'
+                   '  "-1.000001s",'
+                   '  "10.011s",'
+                   '  "-315576000000s",'
+                   '  "315576000000s"'
+                   ']'
+                   '}'))
+    parsed_message = json_format_proto3_pb2.TestDuration()
+    self.CheckParseBack(message, parsed_message)
+
+  def testFieldMaskMessage(self):
+    message = json_format_proto3_pb2.TestFieldMask()
+    message.value.paths.append('foo.bar')
+    message.value.paths.append('bar')
+    self.assertEqual(
+        json_format.MessageToJson(message, True),
+        '{\n'
+        '  "value": "foo.bar,bar"\n'
+        '}')
+    parsed_message = json_format_proto3_pb2.TestFieldMask()
+    self.CheckParseBack(message, parsed_message)
+
+  def testWrapperMessage(self):
+    message = json_format_proto3_pb2.TestWrapper()
+    message.bool_value.value = False
+    message.int32_value.value = 0
+    message.string_value.value = ''
+    message.bytes_value.value = b''
+    message.repeated_bool_value.add().value = True
+    message.repeated_bool_value.add().value = False
+    self.assertEqual(
+        json.loads(json_format.MessageToJson(message, True)),
+        json.loads('{\n'
+                   '  "int32Value": 0,'
+                   '  "boolValue": false,'
+                   '  "stringValue": "",'
+                   '  "bytesValue": "",'
+                   '  "repeatedBoolValue": [true, false],'
+                   '  "repeatedInt32Value": [],'
+                   '  "repeatedUint32Value": [],'
+                   '  "repeatedFloatValue": [],'
+                   '  "repeatedDoubleValue": [],'
+                   '  "repeatedBytesValue": [],'
+                   '  "repeatedInt64Value": [],'
+                   '  "repeatedUint64Value": [],'
+                   '  "repeatedStringValue": []'
+                   '}'))
+    parsed_message = json_format_proto3_pb2.TestWrapper()
+    self.CheckParseBack(message, parsed_message)
+
+  def testParseNull(self):
+    message = json_format_proto3_pb2.TestMessage()
+    message.repeated_int32_value.append(1)
+    message.repeated_int32_value.append(2)
+    message.repeated_int32_value.append(3)
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    self.FillAllFields(parsed_message)
+    json_format.Parse('{"int32Value": null, '
+                      '"int64Value": null, '
+                      '"uint32Value": null,'
+                      '"uint64Value": null,'
+                      '"floatValue": null,'
+                      '"doubleValue": null,'
+                      '"boolValue": null,'
+                      '"stringValue": null,'
+                      '"bytesValue": null,'
+                      '"messageValue": null,'
+                      '"enumValue": null,'
+                      '"repeatedInt32Value": [1, 2, null, 3],'
+                      '"repeatedInt64Value": null,'
+                      '"repeatedUint32Value": null,'
+                      '"repeatedUint64Value": null,'
+                      '"repeatedFloatValue": null,'
+                      '"repeatedDoubleValue": null,'
+                      '"repeatedBoolValue": null,'
+                      '"repeatedStringValue": null,'
+                      '"repeatedBytesValue": null,'
+                      '"repeatedMessageValue": null,'
+                      '"repeatedEnumValue": null'
+                      '}',
+                      parsed_message)
+    self.assertEqual(message, parsed_message)
+
+  def testNanFloat(self):
+    message = json_format_proto3_pb2.TestMessage()
+    message.float_value = float('nan')
+    text = '{\n  "floatValue": "NaN"\n}'
+    self.assertEqual(json_format.MessageToJson(message), text)
+    parsed_message = json_format_proto3_pb2.TestMessage()
+    json_format.Parse(text, parsed_message)
+    self.assertTrue(math.isnan(parsed_message.float_value))
+
+  def testParseEmptyText(self):
+    self.CheckError('',
+                    r'Failed to load JSON: (Expecting value)|(No JSON)')
+
+  def testParseBadEnumValue(self):
+    self.CheckError(
+        '{"enumValue": 1}',
+        'Enum value must be a string literal with double quotes. '
+        'Type "proto3.EnumType" has no value named 1.')
+    self.CheckError(
+        '{"enumValue": "baz"}',
+        'Enum value must be a string literal with double quotes. '
+        'Type "proto3.EnumType" has no value named baz.')
+
+  def testParseBadIdentifer(self):
+    self.CheckError('{int32Value: 1}',
+                    (r'Failed to load JSON: Expecting property name enclosed '
+                     r'in double quotes: line 1'))
+    self.CheckError('{"unknownName": 1}',
+                    'Message type "proto3.TestMessage" has no field named '
+                    '"unknownName".')
+
+  def testDuplicateField(self):
+    self.CheckError('{"int32Value": 1,\n"int32Value":2}',
+                    'Failed to load JSON: duplicate key int32Value')
+
+  def testInvalidBoolValue(self):
+    self.CheckError('{"boolValue": 1}',
+                    'Failed to parse boolValue field: '
+                    'Expected true or false without quotes.')
+    self.CheckError('{"boolValue": "true"}',
+                    'Failed to parse boolValue field: '
+                    'Expected true or false without quotes.')
+
+  def testInvalidIntegerValue(self):
+    message = json_format_proto3_pb2.TestMessage()
+    text = '{"int32Value": 0x12345}'
+    self.assertRaises(json_format.ParseError,
+                      json_format.Parse, text, message)
+    self.CheckError('{"int32Value": 012345}',
+                    (r'Failed to load JSON: Expecting \',\' delimiter: '
+                     r'line 1'))
+    self.CheckError('{"int32Value": 1.0}',
+                    'Failed to parse int32Value field: '
+                    'Couldn\'t parse integer: 1.0')
+    self.CheckError('{"int32Value": " 1 "}',
+                    'Failed to parse int32Value field: '
+                    'Couldn\'t parse integer: " 1 "')
+    self.CheckError('{"int32Value": 12345678901234567890}',
+                    'Failed to parse int32Value field: Value out of range: '
+                    '12345678901234567890')
+    self.CheckError('{"int32Value": 1e5}',
+                    'Failed to parse int32Value field: '
+                    'Couldn\'t parse integer: 100000.0')
+    self.CheckError('{"uint32Value": -1}',
+                    'Failed to parse uint32Value field: Value out of range: -1')
+
+  def testInvalidFloatValue(self):
+    self.CheckError('{"floatValue": "nan"}',
+                    'Failed to parse floatValue field: Couldn\'t '
+                    'parse float "nan", use "NaN" instead')
+
+  def testInvalidBytesValue(self):
+    self.CheckError('{"bytesValue": "AQI"}',
+                    'Failed to parse bytesValue field: Incorrect padding')
+    self.CheckError('{"bytesValue": "AQI*"}',
+                    'Failed to parse bytesValue field: Incorrect padding')
+
+  def testInvalidMap(self):
+    message = json_format_proto3_pb2.TestMap()
+    text = '{"int32Map": {"null": 2, "2": 3}}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Failed to parse int32Map field: Couldn\'t parse integer: "null"',
+        json_format.Parse, text, message)
+    text = '{"int32Map": {1: 2, "2": 3}}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        (r'Failed to load JSON: Expecting property name enclosed '
+         r'in double quotes: line 1'),
+        json_format.Parse, text, message)
+    text = r'{"stringMap": {"a": 3, "\u0061": 2}}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Failed to load JSON: duplicate key a',
+        json_format.Parse, text, message)
+    text = '{"boolMap": {"null": 1}}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Failed to parse boolMap field: Expect "true" or "false", not null.',
+        json_format.Parse, text, message)
+
+  def testInvalidTimestamp(self):
+    message = json_format_proto3_pb2.TestTimestamp()
+    text = '{"value": "10000-01-01T00:00:00.00Z"}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'time data \'10000-01-01T00:00:00\' does not match'
+        ' format \'%Y-%m-%dT%H:%M:%S\'',
+        json_format.Parse, text, message)
+    text = '{"value": "1970-01-01T00:00:00.0123456789012Z"}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Failed to parse value field: Failed to parse Timestamp: '
+        'nanos 0123456789012 more than 9 fractional digits.',
+        json_format.Parse, text, message)
+    text = '{"value": "1972-01-01T01:00:00.01+08"}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        (r'Failed to parse value field: Invalid timezone offset value: \+08'),
+        json_format.Parse, text, message)
+    # Time smaller than minimum time.
+    text = '{"value": "0000-01-01T00:00:00Z"}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Failed to parse value field: year is out of range',
+        json_format.Parse, text, message)
+    # Time bigger than maxinum time.
+    message.value.seconds = 253402300800
+    self.assertRaisesRegexp(
+        json_format.SerializeToJsonError,
+        'Failed to serialize value field: year is out of range',
+        json_format.MessageToJson, message)
+
+  def testInvalidOneof(self):
+    message = json_format_proto3_pb2.TestOneof()
+    text = '{"oneofInt32Value": 1, "oneofStringValue": "2"}'
+    self.assertRaisesRegexp(
+        json_format.ParseError,
+        'Message type "proto3.TestOneof"'
+        ' should not have multiple "oneof_value" oneof fields.',
+        json_format.Parse, text, message)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/message_factory_test.py b/python/google/protobuf/internal/message_factory_test.py
index 0d880a75..9ec54fff 100644
--- a/python/google/protobuf/internal/message_factory_test.py
+++ b/python/google/protobuf/internal/message_factory_test.py
@@ -34,10 +34,7 @@
 
 __author__ = 'matthewtoia@google.com (Matt Toia)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import descriptor_pb2
 from google.protobuf.internal import factory_test1_pb2
 from google.protobuf.internal import factory_test2_pb2
@@ -45,7 +42,6 @@ from google.protobuf import descriptor_database
 from google.protobuf import descriptor_pool
 from google.protobuf import message_factory
 
-
 class MessageFactoryTest(unittest.TestCase):
 
   def setUp(self):
diff --git a/python/google/protobuf/internal/message_test.py b/python/google/protobuf/internal/message_test.py
index d99b89be..604c426a 100755
--- a/python/google/protobuf/internal/message_test.py
+++ b/python/google/protobuf/internal/message_test.py
@@ -43,22 +43,16 @@ abstract interface.
 
 __author__ = 'gps@google.com (Gregory P. Smith)'
 
+
 import collections
 import copy
 import math
 import operator
 import pickle
-import sys
-
 import six
+import sys
 
-if six.PY3:
-  long = int
-
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf.internal import _parameterized
 from google.protobuf import map_unittest_pb2
 from google.protobuf import unittest_pb2
@@ -68,6 +62,9 @@ from google.protobuf.internal import packed_field_test_pb2
 from google.protobuf.internal import test_util
 from google.protobuf import message
 
+if six.PY3:
+  long = int
+
 # Python pre-2.6 does not have isinf() or isnan() functions, so we have
 # to provide our own.
 def isnan(val):
@@ -442,7 +439,7 @@ class MessageTest(unittest.TestCase):
     message.repeated_nested_message.add().bb = 24
     message.repeated_nested_message.add().bb = 10
     message.repeated_nested_message.sort(key=lambda z: z.bb // 10)
-    self.assertEquals(
+    self.assertEqual(
         [13, 11, 10, 21, 20, 24, 33],
         [n.bb for n in message.repeated_nested_message])
 
@@ -451,7 +448,7 @@ class MessageTest(unittest.TestCase):
     pb = message.SerializeToString()
     message.Clear()
     message.MergeFromString(pb)
-    self.assertEquals(
+    self.assertEqual(
         [13, 11, 10, 21, 20, 24, 33],
         [n.bb for n in message.repeated_nested_message])
 
@@ -914,7 +911,6 @@ class MessageTest(unittest.TestCase):
     with self.assertRaises(pickle.PickleError) as _:
       pickle.dumps(m.repeated_int32, pickle.HIGHEST_PROTOCOL)
 
-
   def testSortEmptyRepeatedCompositeContainer(self, message_module):
     """Exercise a scenario that has led to segfaults in the past.
     """
diff --git a/python/google/protobuf/internal/missing_enum_values.proto b/python/google/protobuf/internal/missing_enum_values.proto
index 161fc5e1..1850be5b 100644
--- a/python/google/protobuf/internal/missing_enum_values.proto
+++ b/python/google/protobuf/internal/missing_enum_values.proto
@@ -50,3 +50,7 @@ message TestMissingEnumValues {
   repeated NestedEnum repeated_nested_enum = 2;
   repeated NestedEnum packed_nested_enum = 3 [packed = true];
 }
+
+message JustString {
+  required string dummy = 1;
+}
diff --git a/python/google/protobuf/internal/proto_builder_test.py b/python/google/protobuf/internal/proto_builder_test.py
index 1eda10fb..e0467251 100644
--- a/python/google/protobuf/internal/proto_builder_test.py
+++ b/python/google/protobuf/internal/proto_builder_test.py
@@ -34,14 +34,10 @@
 
 try:
     from collections import OrderedDict
-except ImportError: 
-    from ordereddict import OrderedDict  #PY26
-
-try:
-  import unittest2 as unittest  #PY26
 except ImportError:
-  import unittest
-
+    from ordereddict import OrderedDict  #PY26
+import collections
+import unittest
 from google.protobuf import descriptor_pb2
 from google.protobuf import descriptor_pool
 from google.protobuf import proto_builder
diff --git a/python/google/protobuf/internal/python_message.py b/python/google/protobuf/internal/python_message.py
index 4e5032a7..2b87f704 100755
--- a/python/google/protobuf/internal/python_message.py
+++ b/python/google/protobuf/internal/python_message.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2007 Google Inc. All Rights Reserved.
-#
 # This code is meant to work on Python 2.4 and above only.
 #
 # TODO(robinson): Helpers for verbose, common checks like seeing if a
diff --git a/python/google/protobuf/internal/reflection_test.py b/python/google/protobuf/internal/reflection_test.py
index 26611353..6815c238 100755
--- a/python/google/protobuf/internal/reflection_test.py
+++ b/python/google/protobuf/internal/reflection_test.py
@@ -38,14 +38,10 @@ pure-Python protocol compiler.
 import copy
 import gc
 import operator
-import struct
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
-
 import six
+import struct
 
+import unittest
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_mset_pb2
 from google.protobuf import unittest_pb2
@@ -1627,7 +1623,7 @@ class ReflectionTest(unittest.TestCase):
     self.assertFalse(proto.IsInitialized(errors))
     self.assertEqual(errors, ['a', 'b', 'c'])
 
-  @unittest.skipIf(
+  @test_util.skipIf(
       api_implementation.Type() != 'cpp' or api_implementation.Version() != 2,
       'Errors are only available from the most recent C++ implementation.')
   def testFileDescriptorErrors(self):
@@ -1799,7 +1795,6 @@ class ReflectionTest(unittest.TestCase):
     # Just check the default value.
     self.assertEqual(57, msg.inner.value)
 
-
 #  Since we had so many tests for protocol buffer equality, we broke these out
 #  into separate TestCase classes.
 
@@ -2827,7 +2822,7 @@ class OptionsTest(unittest.TestCase):
 
 class ClassAPITest(unittest.TestCase):
 
-  @unittest.skipIf(
+  @test_util.skipIf(
       api_implementation.Type() == 'cpp' and api_implementation.Version() == 2,
       'C++ implementation requires a call to MakeDescriptor()')
   def testMakeClassWithNestedDescriptor(self):
diff --git a/python/google/protobuf/internal/service_reflection_test.py b/python/google/protobuf/internal/service_reflection_test.py
index 98614b77..564e2d1a 100755
--- a/python/google/protobuf/internal/service_reflection_test.py
+++ b/python/google/protobuf/internal/service_reflection_test.py
@@ -34,10 +34,7 @@
 
 __author__ = 'petar@google.com (Petar Petrov)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import unittest_pb2
 from google.protobuf import service_reflection
 from google.protobuf import service
diff --git a/python/google/protobuf/internal/symbol_database_test.py b/python/google/protobuf/internal/symbol_database_test.py
index 97442262..7fb4b56d 100644
--- a/python/google/protobuf/internal/symbol_database_test.py
+++ b/python/google/protobuf/internal/symbol_database_test.py
@@ -32,27 +32,29 @@
 
 """Tests for google.protobuf.symbol_database."""
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import unittest_pb2
+from google.protobuf import descriptor
 from google.protobuf import symbol_database
 
-
 class SymbolDatabaseTest(unittest.TestCase):
 
   def _Database(self):
-    db = symbol_database.SymbolDatabase()
-    # Register representative types from unittest_pb2.
-    db.RegisterFileDescriptor(unittest_pb2.DESCRIPTOR)
-    db.RegisterMessage(unittest_pb2.TestAllTypes)
-    db.RegisterMessage(unittest_pb2.TestAllTypes.NestedMessage)
-    db.RegisterMessage(unittest_pb2.TestAllTypes.OptionalGroup)
-    db.RegisterMessage(unittest_pb2.TestAllTypes.RepeatedGroup)
-    db.RegisterEnumDescriptor(unittest_pb2.ForeignEnum.DESCRIPTOR)
-    db.RegisterEnumDescriptor(unittest_pb2.TestAllTypes.NestedEnum.DESCRIPTOR)
-    return db
+    # TODO(b/17734095): Remove this difference when the C++ implementation
+    # supports multiple databases.
+    if descriptor._USE_C_DESCRIPTORS:
+      return symbol_database.Default()
+    else:
+      db = symbol_database.SymbolDatabase()
+      # Register representative types from unittest_pb2.
+      db.RegisterFileDescriptor(unittest_pb2.DESCRIPTOR)
+      db.RegisterMessage(unittest_pb2.TestAllTypes)
+      db.RegisterMessage(unittest_pb2.TestAllTypes.NestedMessage)
+      db.RegisterMessage(unittest_pb2.TestAllTypes.OptionalGroup)
+      db.RegisterMessage(unittest_pb2.TestAllTypes.RepeatedGroup)
+      db.RegisterEnumDescriptor(unittest_pb2.ForeignEnum.DESCRIPTOR)
+      db.RegisterEnumDescriptor(unittest_pb2.TestAllTypes.NestedEnum.DESCRIPTOR)
+      return db
 
   def testGetPrototype(self):
     instance = self._Database().GetPrototype(
diff --git a/python/google/protobuf/internal/test_util.py b/python/google/protobuf/internal/test_util.py
index ac88fa81..539236b4 100755
--- a/python/google/protobuf/internal/test_util.py
+++ b/python/google/protobuf/internal/test_util.py
@@ -38,6 +38,13 @@ __author__ = 'robinson@google.com (Will Robinson)'
 
 import os.path
 
+import sys
+# PY2.6 compatible skipIf
+if sys.version_info < (2, 7):
+  from unittest2 import skipIf
+else:
+  from unittest import skipIf
+
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import descriptor_pb2
diff --git a/python/google/protobuf/internal/text_encoding_test.py b/python/google/protobuf/internal/text_encoding_test.py
index 338a287b..9e7b9ce4 100755
--- a/python/google/protobuf/internal/text_encoding_test.py
+++ b/python/google/protobuf/internal/text_encoding_test.py
@@ -32,10 +32,7 @@
 
 """Tests for google.protobuf.text_encoding."""
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import text_encoding
 
 TEST_VALUES = [
diff --git a/python/google/protobuf/internal/text_format_test.py b/python/google/protobuf/internal/text_format_test.py
index d332b77d..fb4addeb 100755
--- a/python/google/protobuf/internal/text_format_test.py
+++ b/python/google/protobuf/internal/text_format_test.py
@@ -34,14 +34,12 @@
 
 __author__ = 'kenton@google.com (Kenton Varda)'
 
+
 import re
 import six
 import string
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf.internal import _parameterized
 
 from google.protobuf import map_unittest_pb2
@@ -389,7 +387,7 @@ class TextFormatTest(TextFormatBase):
 # Ideally the schemas would be made more similar so these tests could pass.
 class OnlyWorksWithProto2RightNowTests(TextFormatBase):
 
-  def testPrintAllFieldsPointy(self, message_module):
+  def testPrintAllFieldsPointy(self):
     message = unittest_pb2.TestAllTypes()
     test_util.SetAllFields(message)
     self.CompareToGoldenFile(
diff --git a/python/google/protobuf/internal/type_checkers.py b/python/google/protobuf/internal/type_checkers.py
index 8fa3d8c8..f30ca6a8 100755
--- a/python/google/protobuf/internal/type_checkers.py
+++ b/python/google/protobuf/internal/type_checkers.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2008 Google Inc. All Rights Reserved.
-
 """Provides type checking routines.
 
 This module defines type checking utilities in the forms of dictionaries:
@@ -52,6 +50,7 @@ import six
 if six.PY3:
   long = int
 
+from google.protobuf.internal import api_implementation
 from google.protobuf.internal import decoder
 from google.protobuf.internal import encoder
 from google.protobuf.internal import wire_format
diff --git a/python/google/protobuf/internal/unknown_fields_test.py b/python/google/protobuf/internal/unknown_fields_test.py
index 011d3b55..25b447e1 100755
--- a/python/google/protobuf/internal/unknown_fields_test.py
+++ b/python/google/protobuf/internal/unknown_fields_test.py
@@ -35,11 +35,7 @@
 
 __author__ = 'bohdank@google.com (Bohdan Koval)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
-
+import unittest
 from google.protobuf import unittest_mset_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import unittest_proto3_arena_pb2
@@ -52,7 +48,7 @@ from google.protobuf.internal import type_checkers
 
 
 def SkipIfCppImplementation(func):
-  return unittest.skipIf(
+  return test_util.skipIf(
       api_implementation.Type() == 'cpp' and api_implementation.Version() == 2,
       'C++ implementation does not expose unknown fields to Python')(func)
 
@@ -262,6 +258,19 @@ class UnknownEnumValuesTest(unittest.TestCase):
         decoder(value, 0, len(value), self.message, result_dict)
     return result_dict[field_descriptor]
 
+  def testUnknownParseMismatchEnumValue(self):
+    just_string = missing_enum_values_pb2.JustString()
+    just_string.dummy = 'blah'
+
+    missing = missing_enum_values_pb2.TestEnumValues()
+    # The parse is invalid, storing the string proto into the set of
+    # unknown fields.
+    missing.ParseFromString(just_string.SerializeToString())
+
+    # Fetching the enum field shouldn't crash, instead returning the
+    # default value.
+    self.assertEqual(missing.optional_nested_enum, 0)
+
   @SkipIfCppImplementation
   def testUnknownEnumValue(self):
     self.assertFalse(self.missing_message.HasField('optional_nested_enum'))
diff --git a/python/google/protobuf/internal/wire_format_test.py b/python/google/protobuf/internal/wire_format_test.py
index f659d18e..78dc1167 100755
--- a/python/google/protobuf/internal/wire_format_test.py
+++ b/python/google/protobuf/internal/wire_format_test.py
@@ -34,10 +34,7 @@
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
-try:
-  import unittest2 as unittest
-except ImportError:
-  import unittest
+import unittest
 from google.protobuf import message
 from google.protobuf.internal import wire_format
 
diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
new file mode 100644
index 00000000..09110e04
--- /dev/null
+++ b/python/google/protobuf/json_format.py
@@ -0,0 +1,601 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# https://developers.google.com/protocol-buffers/
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""Contains routines for printing protocol messages in JSON format."""
+
+__author__ = 'jieluo@google.com (Jie Luo)'
+
+import base64
+from datetime import datetime
+import json
+import math
+import re
+
+from google.protobuf import descriptor
+
+_TIMESTAMPFOMAT = '%Y-%m-%dT%H:%M:%S'
+_NUMBER = re.compile(u'[0-9+-][0-9e.+-]*')
+_INTEGER = re.compile(u'[0-9+-]')
+_INT_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_INT32,
+                        descriptor.FieldDescriptor.CPPTYPE_UINT32,
+                        descriptor.FieldDescriptor.CPPTYPE_INT64,
+                        descriptor.FieldDescriptor.CPPTYPE_UINT64])
+_INT64_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_INT64,
+                          descriptor.FieldDescriptor.CPPTYPE_UINT64])
+_FLOAT_TYPES = frozenset([descriptor.FieldDescriptor.CPPTYPE_FLOAT,
+                          descriptor.FieldDescriptor.CPPTYPE_DOUBLE])
+if str is bytes:
+  _UNICODETYPE = unicode
+else:
+  _UNICODETYPE = str
+
+
+class SerializeToJsonError(Exception):
+  """Thrown if serialization to JSON fails."""
+
+
+class ParseError(Exception):
+  """Thrown in case of parsing error."""
+
+
+def MessageToJson(message, including_default_value_fields=False):
+  """Converts protobuf message to JSON format.
+
+  Args:
+    message: The protocol buffers message instance to serialize.
+    including_default_value_fields: If True, singular primitive fields,
+        repeated fields, and map fields will always be serialized.  If
+        False, only serialize non-empty fields.  Singular message fields
+        and oneof fields are not affected by this option.
+
+  Returns:
+    A string containing the JSON formatted protocol buffer message.
+  """
+  js = _MessageToJsonObject(message, including_default_value_fields)
+  return json.dumps(js, indent=2)
+
+
+def _MessageToJsonObject(message, including_default_value_fields):
+  """Converts message to an object according to Proto3 JSON Specification."""
+  message_descriptor = message.DESCRIPTOR
+  if _IsTimestampMessage(message_descriptor):
+    return _TimestampMessageToJsonObject(message)
+  if _IsDurationMessage(message_descriptor):
+    return _DurationMessageToJsonObject(message)
+  if _IsFieldMaskMessage(message_descriptor):
+    return _FieldMaskMessageToJsonObject(message)
+  if _IsWrapperMessage(message_descriptor):
+    return _WrapperMessageToJsonObject(message)
+  return _RegularMessageToJsonObject(message, including_default_value_fields)
+
+
+def _IsMapEntry(field):
+  return (field.type == descriptor.FieldDescriptor.TYPE_MESSAGE and
+          field.message_type.has_options and
+          field.message_type.GetOptions().map_entry)
+
+
+def _RegularMessageToJsonObject(message, including_default_value_fields):
+  """Converts normal message according to Proto3 JSON Specification."""
+  js = {}
+  fields = message.ListFields()
+
+  try:
+    for field, value in fields:
+      name = field.camelcase_name
+      if _IsMapEntry(field):
+        # Convert a map field.
+        js_map = {}
+        for key in value:
+          js_map[key] = _ConvertFieldToJsonObject(
+              field.message_type.fields_by_name['value'],
+              value[key], including_default_value_fields)
+        js[name] = js_map
+      elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+        # Convert a repeated field.
+        repeated = []
+        for element in value:
+          repeated.append(_ConvertFieldToJsonObject(
+              field, element, including_default_value_fields))
+        js[name] = repeated
+      else:
+        js[name] = _ConvertFieldToJsonObject(
+            field, value, including_default_value_fields)
+
+    # Serialize default value if including_default_value_fields is True.
+    if including_default_value_fields:
+      message_descriptor = message.DESCRIPTOR
+      for field in message_descriptor.fields:
+        # Singular message fields and oneof fields will not be affected.
+        if ((field.label != descriptor.FieldDescriptor.LABEL_REPEATED and
+             field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE) or
+            field.containing_oneof):
+          continue
+        name = field.camelcase_name
+        if name in js:
+          # Skip the field which has been serailized already.
+          continue
+        if _IsMapEntry(field):
+          js[name] = {}
+        elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+          js[name] = []
+        else:
+          js[name] = _ConvertFieldToJsonObject(field, field.default_value)
+
+  except ValueError as e:
+    raise SerializeToJsonError(
+        'Failed to serialize {0} field: {1}'.format(field.name, e))
+
+  return js
+
+
+def _ConvertFieldToJsonObject(
+    field, value, including_default_value_fields=False):
+  """Converts field value according to Proto3 JSON Specification."""
+  if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+    return _MessageToJsonObject(value, including_default_value_fields)
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
+    enum_value = field.enum_type.values_by_number.get(value, None)
+    if enum_value is not None:
+      return enum_value.name
+    else:
+      raise SerializeToJsonError('Enum field contains an integer value '
+                                 'which can not mapped to an enum value.')
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
+    if field.type == descriptor.FieldDescriptor.TYPE_BYTES:
+      # Use base64 Data encoding for bytes
+      return base64.b64encode(value).decode('utf-8')
+    else:
+      return value
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
+    if value:
+      return True
+    else:
+      return False
+  elif field.cpp_type in _INT64_TYPES:
+    return str(value)
+  elif field.cpp_type in _FLOAT_TYPES:
+    if math.isinf(value):
+      if value < 0.0:
+        return '-Infinity'
+      else:
+        return 'Infinity'
+    if math.isnan(value):
+      return 'NaN'
+  return value
+
+
+def _IsTimestampMessage(message_descriptor):
+  return (message_descriptor.name == 'Timestamp' and
+          message_descriptor.file.name == 'google/protobuf/timestamp.proto')
+
+
+def _TimestampMessageToJsonObject(message):
+  """Converts Timestamp message according to Proto3 JSON Specification."""
+  nanos = message.nanos % 1e9
+  dt = datetime.utcfromtimestamp(
+      message.seconds + (message.nanos - nanos) / 1e9)
+  result = dt.isoformat()
+  if (nanos % 1e9) == 0:
+    # If there are 0 fractional digits, the fractional
+    # point '.' should be omitted when serializing.
+    return result + 'Z'
+  if (nanos % 1e6) == 0:
+    # Serialize 3 fractional digits.
+    return result + '.%03dZ' % (nanos / 1e6)
+  if (nanos % 1e3) == 0:
+    # Serialize 6 fractional digits.
+    return result + '.%06dZ' % (nanos / 1e3)
+  # Serialize 9 fractional digits.
+  return result + '.%09dZ' % nanos
+
+
+def _IsDurationMessage(message_descriptor):
+  return (message_descriptor.name == 'Duration' and
+          message_descriptor.file.name == 'google/protobuf/duration.proto')
+
+
+def _DurationMessageToJsonObject(message):
+  """Converts Duration message according to Proto3 JSON Specification."""
+  if message.seconds < 0 or message.nanos < 0:
+    result = '-'
+    seconds = - message.seconds + int((0 - message.nanos) / 1e9)
+    nanos = (0 - message.nanos) % 1e9
+  else:
+    result = ''
+    seconds = message.seconds + int(message.nanos / 1e9)
+    nanos = message.nanos % 1e9
+  result += '%d' % seconds
+  if (nanos % 1e9) == 0:
+    # If there are 0 fractional digits, the fractional
+    # point '.' should be omitted when serializing.
+    return result + 's'
+  if (nanos % 1e6) == 0:
+    # Serialize 3 fractional digits.
+    return result + '.%03ds' % (nanos / 1e6)
+  if (nanos % 1e3) == 0:
+    # Serialize 6 fractional digits.
+    return result + '.%06ds' % (nanos / 1e3)
+    # Serialize 9 fractional digits.
+  return result + '.%09ds' % nanos
+
+
+def _IsFieldMaskMessage(message_descriptor):
+  return (message_descriptor.name == 'FieldMask' and
+          message_descriptor.file.name == 'google/protobuf/field_mask.proto')
+
+
+def _FieldMaskMessageToJsonObject(message):
+  """Converts FieldMask message according to Proto3 JSON Specification."""
+  result = ''
+  first = True
+  for path in message.paths:
+    if not first:
+      result += ','
+    result += path
+    first = False
+  return result
+
+
+def _IsWrapperMessage(message_descriptor):
+  return message_descriptor.file.name == 'google/protobuf/wrappers.proto'
+
+
+def _WrapperMessageToJsonObject(message):
+  return _ConvertFieldToJsonObject(
+      message.DESCRIPTOR.fields_by_name['value'], message.value)
+
+
+def _DuplicateChecker(js):
+  result = {}
+  for name, value in js:
+    if name in result:
+      raise ParseError('Failed to load JSON: duplicate key ' + name)
+    result[name] = value
+  return result
+
+
+def Parse(text, message):
+  """Parses a JSON representation of a protocol message into a message.
+
+  Args:
+    text: Message JSON representation.
+    message: A protocol beffer message to merge into.
+
+  Returns:
+    The same message passed as argument.
+
+  Raises::
+    ParseError: On JSON parsing problems.
+  """
+  if not isinstance(text, _UNICODETYPE): text = text.decode('utf-8')
+  try:
+    js = json.loads(text, object_pairs_hook=_DuplicateChecker)
+  except ValueError as e:
+    raise ParseError('Failed to load JSON: ' + str(e))
+  _ConvertFieldValuePair(js, message)
+  return message
+
+
+def _ConvertFieldValuePair(js, message):
+  """Convert field value pairs into regular message.
+
+  Args:
+    js: A JSON object to convert the field value pairs.
+    message: A regular protocol message to record the data.
+
+  Raises:
+    ParseError: In case of problems converting.
+  """
+  names = []
+  message_descriptor = message.DESCRIPTOR
+  for name in js:
+    try:
+      field = message_descriptor.fields_by_camelcase_name.get(name, None)
+      if not field:
+        raise ParseError(
+            'Message type "{0}" has no field named "{1}".'.format(
+                message_descriptor.full_name, name))
+      if name in names:
+        raise ParseError(
+            'Message type "{0}" should not have multiple "{1}" fields.'.format(
+                message.DESCRIPTOR.full_name, name))
+      names.append(name)
+      # Check no other oneof field is parsed.
+      if field.containing_oneof is not None:
+        oneof_name = field.containing_oneof.name
+        if oneof_name in names:
+          raise ParseError('Message type "{0}" should not have multiple "{1}" '
+                           'oneof fields.'.format(
+                               message.DESCRIPTOR.full_name, oneof_name))
+        names.append(oneof_name)
+
+      value = js[name]
+      if value is None:
+        message.ClearField(field.name)
+        continue
+
+      # Parse field value.
+      if _IsMapEntry(field):
+        message.ClearField(field.name)
+        _ConvertMapFieldValue(value, message, field)
+      elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
+        message.ClearField(field.name)
+        if not isinstance(value, list):
+          raise ParseError('repeated field {0} must be in [] which is '
+                           '{1}'.format(name, value))
+        for item in value:
+          if item is None:
+            continue
+          if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+            sub_message = getattr(message, field.name).add()
+            _ConvertMessage(item, sub_message)
+          else:
+            getattr(message, field.name).append(
+                _ConvertScalarFieldValue(item, field))
+      elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+        sub_message = getattr(message, field.name)
+        _ConvertMessage(value, sub_message)
+      else:
+        setattr(message, field.name, _ConvertScalarFieldValue(value, field))
+    except ParseError as e:
+      if field and field.containing_oneof is None:
+        raise ParseError('Failed to parse {0} field: {1}'.format(name, e))
+      else:
+        raise ParseError(str(e))
+    except ValueError as e:
+      raise ParseError('Failed to parse {0} field: {1}'.format(name, e))
+    except TypeError as e:
+      raise ParseError('Failed to parse {0} field: {1}'.format(name, e))
+
+
+def _ConvertMessage(value, message):
+  """Convert a JSON object into a message.
+
+  Args:
+    value: A JSON object.
+    message: A WKT or regular protocol message to record the data.
+
+  Raises:
+    ParseError: In case of convert problems.
+  """
+  message_descriptor = message.DESCRIPTOR
+  if _IsTimestampMessage(message_descriptor):
+    _ConvertTimestampMessage(value, message)
+  elif _IsDurationMessage(message_descriptor):
+    _ConvertDurationMessage(value, message)
+  elif _IsFieldMaskMessage(message_descriptor):
+    _ConvertFieldMaskMessage(value, message)
+  elif _IsWrapperMessage(message_descriptor):
+    _ConvertWrapperMessage(value, message)
+  else:
+    _ConvertFieldValuePair(value, message)
+
+
+def _ConvertTimestampMessage(value, message):
+  """Convert a JSON representation into Timestamp message."""
+  timezone_offset = value.find('Z')
+  if timezone_offset == -1:
+    timezone_offset = value.find('+')
+  if timezone_offset == -1:
+    timezone_offset = value.rfind('-')
+  if timezone_offset == -1:
+    raise ParseError(
+        'Failed to parse timestamp: missing valid timezone offset.')
+  time_value = value[0:timezone_offset]
+  # Parse datetime and nanos
+  point_position = time_value.find('.')
+  if point_position == -1:
+    second_value = time_value
+    nano_value = ''
+  else:
+    second_value = time_value[:point_position]
+    nano_value = time_value[point_position + 1:]
+  date_object = datetime.strptime(second_value, _TIMESTAMPFOMAT)
+  seconds = (date_object - datetime(1970, 1, 1)).total_seconds()
+  if len(nano_value) > 9:
+    raise ParseError(
+        'Failed to parse Timestamp: nanos {0} more than '
+        '9 fractional digits.'.format(nano_value))
+  if nano_value:
+    nanos = round(float('0.' + nano_value) * 1e9)
+  else:
+    nanos = 0
+  # Parse timezone offsets
+  if value[timezone_offset] == 'Z':
+    if len(value) != timezone_offset + 1:
+      raise ParseError(
+          'Failed to parse timestamp: invalid trailing data {0}.'.format(value))
+  else:
+    timezone = value[timezone_offset:]
+    pos = timezone.find(':')
+    if pos == -1:
+      raise ParseError(
+          'Invalid timezone offset value: ' + timezone)
+    if timezone[0] == '+':
+      seconds += (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
+    else:
+      seconds -= (int(timezone[1:pos])*60+int(timezone[pos+1:]))*60
+  # Set seconds and nanos
+  message.seconds = int(seconds)
+  message.nanos = int(nanos)
+
+
+def _ConvertDurationMessage(value, message):
+  """Convert a JSON representation into Duration message."""
+  if value[-1] != 's':
+    raise ParseError(
+        'Duration must end with letter "s": ' + value)
+  try:
+    duration = float(value[:-1])
+  except ValueError:
+    raise ParseError(
+        'Couldn\'t parse duration: ' + value)
+  message.seconds = int(duration)
+  message.nanos = int(round((duration - message.seconds) * 1e9))
+
+
+def _ConvertFieldMaskMessage(value, message):
+  """Convert a JSON representation into FieldMask message."""
+  for path in value.split(','):
+    message.paths.append(path)
+
+
+def _ConvertWrapperMessage(value, message):
+  """Convert a JSON representation into Wrapper message."""
+  field = message.DESCRIPTOR.fields_by_name['value']
+  setattr(message, 'value', _ConvertScalarFieldValue(value, field))
+
+
+def _ConvertMapFieldValue(value, message, field):
+  """Convert map field value for a message map field.
+
+  Args:
+    value: A JSON object to convert the map field value.
+    message: A protocol message to record the converted data.
+    field: The descriptor of the map field to be converted.
+
+  Raises:
+    ParseError: In case of convert problems.
+  """
+  if not isinstance(value, dict):
+    raise ParseError(
+        'Map fieled {0} must be in {} which is {1}.'.format(field.name, value))
+  key_field = field.message_type.fields_by_name['key']
+  value_field = field.message_type.fields_by_name['value']
+  for key in value:
+    key_value = _ConvertScalarFieldValue(key, key_field, True)
+    if value_field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
+      _ConvertMessage(value[key], getattr(message, field.name)[key_value])
+    else:
+      getattr(message, field.name)[key_value] = _ConvertScalarFieldValue(
+          value[key], value_field)
+
+
+def _ConvertScalarFieldValue(value, field, require_quote=False):
+  """Convert a single scalar field value.
+
+  Args:
+    value: A scalar value to convert the scalar field value.
+    field: The descriptor of the field to convert.
+    require_quote: If True, '"' is required for the field value.
+
+  Returns:
+    The converted scalar field value
+
+  Raises:
+    ParseError: In case of convert problems.
+  """
+  if field.cpp_type in _INT_TYPES:
+    return _ConvertInteger(value)
+  elif field.cpp_type in _FLOAT_TYPES:
+    return _ConvertFloat(value)
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
+    return _ConvertBool(value, require_quote)
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
+    if field.type == descriptor.FieldDescriptor.TYPE_BYTES:
+      return base64.b64decode(value)
+    else:
+      return value
+  elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
+    # Convert an enum value.
+    enum_value = field.enum_type.values_by_name.get(value, None)
+    if enum_value is None:
+      raise ParseError(
+          'Enum value must be a string literal with double quotes. '
+          'Type "{0}" has no value named {1}.'.format(
+              field.enum_type.full_name, value))
+    return enum_value.number
+
+
+def _ConvertInteger(value):
+  """Convert an integer.
+
+  Args:
+    value: A scalar value to convert.
+
+  Returns:
+    The integer value.
+
+  Raises:
+    ParseError: If an integer couldn't be consumed.
+  """
+  if isinstance(value, float):
+    raise ParseError('Couldn\'t parse integer: {0}'.format(value))
+
+  if isinstance(value, _UNICODETYPE) and not _INTEGER.match(value):
+    raise ParseError('Couldn\'t parse integer: "{0}"'.format(value))
+
+  return int(value)
+
+
+def _ConvertFloat(value):
+  """Convert an floating point number."""
+  if value == 'nan':
+    raise ParseError('Couldn\'t parse float "nan", use "NaN" instead')
+  try:
+    # Assume Python compatible syntax.
+    return float(value)
+  except ValueError:
+    # Check alternative spellings.
+    if value == '-Infinity':
+      return float('-inf')
+    elif value == 'Infinity':
+      return float('inf')
+    elif value == 'NaN':
+      return float('nan')
+    else:
+      raise ParseError('Couldn\'t parse float: {0}'.format(value))
+
+
+def _ConvertBool(value, require_quote):
+  """Convert a boolean value.
+
+  Args:
+    value: A scalar value to convert.
+    require_quote: If True, '"' is required for the boolean value.
+
+  Returns:
+    The bool parsed.
+
+  Raises:
+    ParseError: If a boolean value couldn't be consumed.
+  """
+  if require_quote:
+    if value == 'true':
+      return True
+    elif value == 'false':
+      return False
+    else:
+      raise ParseError('Expect "true" or "false", not {0}.'.format(value))
+
+  if not isinstance(value, bool):
+    raise ParseError('Expected true or false without quotes.')
+  return value
diff --git a/python/google/protobuf/message_factory.py b/python/google/protobuf/message_factory.py
index 36062a56..9cd9c2a8 100644
--- a/python/google/protobuf/message_factory.py
+++ b/python/google/protobuf/message_factory.py
@@ -28,8 +28,6 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2012 Google Inc. All Rights Reserved.
-
 """Provides a factory class for generating dynamic messages.
 
 The easiest way to use this class is if you have access to the FileDescriptor
diff --git a/python/google/protobuf/proto_builder.py b/python/google/protobuf/proto_builder.py
index 700e3c25..736caed3 100644
--- a/python/google/protobuf/proto_builder.py
+++ b/python/google/protobuf/proto_builder.py
@@ -48,7 +48,7 @@ def _GetMessageFromFactory(factory, full_name):
     factory: a MessageFactory instance.
     full_name: str, the fully qualified name of the proto type.
   Returns:
-    a class, for the type identified by full_name.
+    A class, for the type identified by full_name.
   Raises:
     KeyError, if the proto is not found in the factory's descriptor pool.
   """
@@ -57,7 +57,7 @@ def _GetMessageFromFactory(factory, full_name):
   return proto_cls
 
 
-def MakeSimpleProtoClass(fields, full_name, pool=None):
+def MakeSimpleProtoClass(fields, full_name=None, pool=None):
   """Create a Protobuf class whose fields are basic types.
 
   Note: this doesn't validate field names!
@@ -66,18 +66,20 @@ def MakeSimpleProtoClass(fields, full_name, pool=None):
     fields: dict of {name: field_type} mappings for each field in the proto. If
         this is an OrderedDict the order will be maintained, otherwise the
         fields will be sorted by name.
-    full_name: str, the fully-qualified name of the proto type.
+    full_name: optional str, the fully-qualified name of the proto type.
     pool: optional DescriptorPool instance.
   Returns:
     a class, the new protobuf class with a FileDescriptor.
   """
   factory = message_factory.MessageFactory(pool=pool)
-  try:
-    proto_cls = _GetMessageFromFactory(factory, full_name)
-    return proto_cls
-  except KeyError:
-    # The factory's DescriptorPool doesn't know about this class yet.
-    pass
+
+  if full_name is not None:
+    try:
+      proto_cls = _GetMessageFromFactory(factory, full_name)
+      return proto_cls
+    except KeyError:
+      # The factory's DescriptorPool doesn't know about this class yet.
+      pass
 
   # Get a list of (name, field_type) tuples from the fields dict. If fields was
   # an OrderedDict we keep the order, but otherwise we sort the field to ensure
@@ -94,6 +96,25 @@ def MakeSimpleProtoClass(fields, full_name, pool=None):
     fields_hash.update(str(f_type).encode('utf-8'))
   proto_file_name = fields_hash.hexdigest() + '.proto'
 
+  # If the proto is anonymous, use the same hash to name it.
+  if full_name is None:
+    full_name = ('net.proto2.python.public.proto_builder.AnonymousProto_' +
+                 fields_hash.hexdigest())
+    try:
+      proto_cls = _GetMessageFromFactory(factory, full_name)
+      return proto_cls
+    except KeyError:
+      # The factory's DescriptorPool doesn't know about this class yet.
+      pass
+
+  # This is the first time we see this proto: add a new descriptor to the pool.
+  factory.pool.Add(
+      _MakeFileDescriptorProto(proto_file_name, full_name, field_items))
+  return _GetMessageFromFactory(factory, full_name)
+
+
+def _MakeFileDescriptorProto(proto_file_name, full_name, field_items):
+  """Populate FileDescriptorProto for MessageFactory's DescriptorPool."""
   package, name = full_name.rsplit('.', 1)
   file_proto = descriptor_pb2.FileDescriptorProto()
   file_proto.name = os.path.join(package.replace('.', '/'), proto_file_name)
@@ -106,6 +127,4 @@ def MakeSimpleProtoClass(fields, full_name, pool=None):
     field_proto.number = f_number
     field_proto.label = descriptor_pb2.FieldDescriptorProto.LABEL_OPTIONAL
     field_proto.type = f_type
-
-  factory.pool.Add(file_proto)
-  return _GetMessageFromFactory(factory, full_name)
+  return file_proto
diff --git a/python/google/protobuf/pyext/descriptor.cc b/python/google/protobuf/pyext/descriptor.cc
index 3806643f..b238fd02 100644
--- a/python/google/protobuf/pyext/descriptor.cc
+++ b/python/google/protobuf/pyext/descriptor.cc
@@ -223,8 +223,7 @@ static PyObject* GetOrBuildOptions(const DescriptorClass *descriptor) {
     options.SerializeToString(&serialized);
     io::CodedInputStream input(
         reinterpret_cast<const uint8*>(serialized.c_str()), serialized.size());
-    input.SetExtensionRegistry(pool->pool,
-                               GetDescriptorPool()->message_factory);
+    input.SetExtensionRegistry(pool->pool, pool->message_factory);
     bool success = cmsg->message->MergePartialFromCodedStream(&input);
     if (!success) {
       PyErr_Format(PyExc_ValueError, "Error parsing Options message");
@@ -414,8 +413,14 @@ static PyObject* GetFile(PyBaseDescriptor *self, void *closure) {
 }
 
 static PyObject* GetConcreteClass(PyBaseDescriptor* self, void *closure) {
+  // Retuns the canonical class for the given descriptor.
+  // This is the class that was registered with the primary descriptor pool
+  // which contains this descriptor.
+  // This might not be the one you expect! For example the returned object does
+  // not know about extensions defined in a custom pool.
   PyObject* concrete_class(cdescriptor_pool::GetMessageClass(
-      GetDescriptorPool(), _GetDescriptor(self)));
+      GetDescriptorPool_FromPool(_GetDescriptor(self)->file()->pool()),
+      _GetDescriptor(self)));
   Py_XINCREF(concrete_class);
   return concrete_class;
 }
@@ -424,6 +429,11 @@ static PyObject* GetFieldsByName(PyBaseDescriptor* self, void *closure) {
   return NewMessageFieldsByName(_GetDescriptor(self));
 }
 
+static PyObject* GetFieldsByCamelcaseName(PyBaseDescriptor* self,
+                                          void *closure) {
+  return NewMessageFieldsByCamelcaseName(_GetDescriptor(self));
+}
+
 static PyObject* GetFieldsByNumber(PyBaseDescriptor* self, void *closure) {
   return NewMessageFieldsByNumber(_GetDescriptor(self));
 }
@@ -564,6 +574,8 @@ static PyGetSetDef Getters[] = {
 
   { "fields", (getter)GetFieldsSeq, NULL, "Fields sequence"},
   { "fields_by_name", (getter)GetFieldsByName, NULL, "Fields by name"},
+  { "fields_by_camelcase_name", (getter)GetFieldsByCamelcaseName, NULL,
+    "Fields by camelCase name"},
   { "fields_by_number", (getter)GetFieldsByNumber, NULL, "Fields by number"},
   { "nested_types", (getter)GetNestedTypesSeq, NULL, "Nested types sequence"},
   { "nested_types_by_name", (getter)GetNestedTypesByName, NULL,
@@ -662,6 +674,10 @@ static PyObject* GetName(PyBaseDescriptor *self, void *closure) {
   return PyString_FromCppString(_GetDescriptor(self)->name());
 }
 
+static PyObject* GetCamelcaseName(PyBaseDescriptor* self, void *closure) {
+  return PyString_FromCppString(_GetDescriptor(self)->camelcase_name());
+}
+
 static PyObject* GetType(PyBaseDescriptor *self, void *closure) {
   return PyInt_FromLong(_GetDescriptor(self)->type());
 }
@@ -850,6 +866,7 @@ static int SetOptions(PyBaseDescriptor *self, PyObject *value,
 static PyGetSetDef Getters[] = {
   { "full_name", (getter)GetFullName, NULL, "Full name"},
   { "name", (getter)GetName, NULL, "Unqualified name"},
+  { "camelcase_name", (getter)GetCamelcaseName, NULL, "Camelcase name"},
   { "type", (getter)GetType, NULL, "C++ Type"},
   { "cpp_type", (getter)GetCppType, NULL, "C++ Type"},
   { "label", (getter)GetLabel, NULL, "Label"},
@@ -1070,6 +1087,15 @@ PyObject* PyEnumDescriptor_FromDescriptor(
       &PyEnumDescriptor_Type, enum_descriptor, NULL);
 }
 
+const EnumDescriptor* PyEnumDescriptor_AsDescriptor(PyObject* obj) {
+  if (!PyObject_TypeCheck(obj, &PyEnumDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Not an EnumDescriptor");
+    return NULL;
+  }
+  return reinterpret_cast<const EnumDescriptor*>(
+      reinterpret_cast<PyBaseDescriptor*>(obj)->descriptor);
+}
+
 namespace enumvalue_descriptor {
 
 // Unchecked accessor to the C++ pointer.
@@ -1359,6 +1385,15 @@ PyObject* PyFileDescriptor_FromDescriptorWithSerializedPb(
   return py_descriptor;
 }
 
+const FileDescriptor* PyFileDescriptor_AsDescriptor(PyObject* obj) {
+  if (!PyObject_TypeCheck(obj, &PyFileDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Not a FileDescriptor");
+    return NULL;
+  }
+  return reinterpret_cast<const FileDescriptor*>(
+      reinterpret_cast<PyBaseDescriptor*>(obj)->descriptor);
+}
+
 namespace oneof_descriptor {
 
 // Unchecked accessor to the C++ pointer.
diff --git a/python/google/protobuf/pyext/descriptor.h b/python/google/protobuf/pyext/descriptor.h
index b2550406..eb99df18 100644
--- a/python/google/protobuf/pyext/descriptor.h
+++ b/python/google/protobuf/pyext/descriptor.h
@@ -72,6 +72,8 @@ PyObject* PyFileDescriptor_FromDescriptorWithSerializedPb(
 // exception set.
 const Descriptor* PyMessageDescriptor_AsDescriptor(PyObject* obj);
 const FieldDescriptor* PyFieldDescriptor_AsDescriptor(PyObject* obj);
+const EnumDescriptor* PyEnumDescriptor_AsDescriptor(PyObject* obj);
+const FileDescriptor* PyFileDescriptor_AsDescriptor(PyObject* obj);
 
 // Returns the raw C++ pointer.
 const void* PyDescriptor_AsVoidPtr(PyObject* obj);
diff --git a/python/google/protobuf/pyext/descriptor_containers.cc b/python/google/protobuf/pyext/descriptor_containers.cc
index 92e11e31..b20f5e4f 100644
--- a/python/google/protobuf/pyext/descriptor_containers.cc
+++ b/python/google/protobuf/pyext/descriptor_containers.cc
@@ -79,9 +79,12 @@ struct PyContainer;
 typedef int (*CountMethod)(PyContainer* self);
 typedef const void* (*GetByIndexMethod)(PyContainer* self, int index);
 typedef const void* (*GetByNameMethod)(PyContainer* self, const string& name);
+typedef const void* (*GetByCamelcaseNameMethod)(PyContainer* self,
+                                                const string& name);
 typedef const void* (*GetByNumberMethod)(PyContainer* self, int index);
 typedef PyObject* (*NewObjectFromItemMethod)(const void* descriptor);
 typedef const string& (*GetItemNameMethod)(const void* descriptor);
+typedef const string& (*GetItemCamelcaseNameMethod)(const void* descriptor);
 typedef int (*GetItemNumberMethod)(const void* descriptor);
 typedef int (*GetItemIndexMethod)(const void* descriptor);
 
@@ -95,6 +98,9 @@ struct DescriptorContainerDef {
   // Retrieve item by name (usually a call to some 'FindByName' method).
   // Used by "by_name" mappings.
   GetByNameMethod get_by_name_fn;
+  // Retrieve item by camelcase name (usually a call to some
+  // 'FindByCamelcaseName' method). Used by "by_camelcase_name" mappings.
+  GetByCamelcaseNameMethod get_by_camelcase_name_fn;
   // Retrieve item by declared number (field tag, or enum value).
   // Used by "by_number" mappings.
   GetByNumberMethod get_by_number_fn;
@@ -102,6 +108,9 @@ struct DescriptorContainerDef {
   NewObjectFromItemMethod new_object_from_item_fn;
   // Retrieve the name of an item. Used by iterators on "by_name" mappings.
   GetItemNameMethod get_item_name_fn;
+  // Retrieve the camelcase name of an item. Used by iterators on
+  // "by_camelcase_name" mappings.
+  GetItemCamelcaseNameMethod get_item_camelcase_name_fn;
   // Retrieve the number of an item. Used by iterators on "by_number" mappings.
   GetItemNumberMethod get_item_number_fn;
   // Retrieve the index of an item for the container type.
@@ -125,6 +134,7 @@ struct PyContainer {
   enum ContainerKind {
     KIND_SEQUENCE,
     KIND_BYNAME,
+    KIND_BYCAMELCASENAME,
     KIND_BYNUMBER,
   } kind;
 };
@@ -172,6 +182,23 @@ static bool _GetItemByKey(PyContainer* self, PyObject* key, const void** item) {
             self, string(name, name_size));
         return true;
       }
+    case PyContainer::KIND_BYCAMELCASENAME:
+      {
+        char* camelcase_name;
+        Py_ssize_t name_size;
+        if (PyString_AsStringAndSize(key, &camelcase_name, &name_size) < 0) {
+          if (PyErr_ExceptionMatches(PyExc_TypeError)) {
+            // Not a string, cannot be in the container.
+            PyErr_Clear();
+            *item = NULL;
+            return true;
+          }
+          return false;
+        }
+        *item = self->container_def->get_by_camelcase_name_fn(
+            self, string(camelcase_name, name_size));
+        return true;
+      }
     case PyContainer::KIND_BYNUMBER:
       {
         Py_ssize_t number = PyNumber_AsSsize_t(key, NULL);
@@ -203,6 +230,12 @@ static PyObject* _NewKey_ByIndex(PyContainer* self, Py_ssize_t index) {
         const string& name(self->container_def->get_item_name_fn(item));
         return PyString_FromStringAndSize(name.c_str(), name.size());
       }
+    case PyContainer::KIND_BYCAMELCASENAME:
+      {
+        const string& name(
+            self->container_def->get_item_camelcase_name_fn(item));
+        return PyString_FromStringAndSize(name.c_str(), name.size());
+      }
     case PyContainer::KIND_BYNUMBER:
       {
         int value = self->container_def->get_item_number_fn(item);
@@ -276,6 +309,9 @@ static PyObject* ContainerRepr(PyContainer* self) {
     case PyContainer::KIND_BYNAME:
       kind = "mapping by name";
       break;
+    case PyContainer::KIND_BYCAMELCASENAME:
+      kind = "mapping by camelCase name";
+      break;
     case PyContainer::KIND_BYNUMBER:
       kind = "mapping by number";
       break;
@@ -731,6 +767,18 @@ static PyObject* NewMappingByName(
   return reinterpret_cast<PyObject*>(self);
 }
 
+static PyObject* NewMappingByCamelcaseName(
+    DescriptorContainerDef* container_def, const void* descriptor) {
+  PyContainer* self = PyObject_New(PyContainer, &DescriptorMapping_Type);
+  if (self == NULL) {
+    return NULL;
+  }
+  self->descriptor = descriptor;
+  self->container_def = container_def;
+  self->kind = PyContainer::KIND_BYCAMELCASENAME;
+  return reinterpret_cast<PyObject*>(self);
+}
+
 static PyObject* NewMappingByNumber(
     DescriptorContainerDef* container_def, const void* descriptor) {
   if (container_def->get_by_number_fn == NULL ||
@@ -889,6 +937,11 @@ static ItemDescriptor GetByName(PyContainer* self, const string& name) {
   return GetDescriptor(self)->FindFieldByName(name);
 }
 
+static ItemDescriptor GetByCamelcaseName(PyContainer* self,
+                                         const string& name) {
+  return GetDescriptor(self)->FindFieldByCamelcaseName(name);
+}
+
 static ItemDescriptor GetByNumber(PyContainer* self, int number) {
   return GetDescriptor(self)->FindFieldByNumber(number);
 }
@@ -905,6 +958,10 @@ static const string& GetItemName(ItemDescriptor item) {
   return item->name();
 }
 
+static const string& GetItemCamelcaseName(ItemDescriptor item) {
+  return item->camelcase_name();
+}
+
 static int GetItemNumber(ItemDescriptor item) {
   return item->number();
 }
@@ -918,9 +975,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)GetByCamelcaseName,
   (GetByNumberMethod)GetByNumber,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)GetItemCamelcaseName,
   (GetItemNumberMethod)GetItemNumber,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -931,6 +990,11 @@ PyObject* NewMessageFieldsByName(ParentDescriptor descriptor) {
   return descriptor::NewMappingByName(&fields::ContainerDef, descriptor);
 }
 
+PyObject* NewMessageFieldsByCamelcaseName(ParentDescriptor descriptor) {
+  return descriptor::NewMappingByCamelcaseName(&fields::ContainerDef,
+                                               descriptor);
+}
+
 PyObject* NewMessageFieldsByNumber(ParentDescriptor descriptor) {
   return descriptor::NewMappingByNumber(&fields::ContainerDef, descriptor);
 }
@@ -972,9 +1036,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1022,9 +1088,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1094,9 +1162,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)NULL,
 };
@@ -1140,9 +1210,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1190,9 +1262,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1258,9 +1332,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)GetByNumber,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)GetItemNumber,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1314,9 +1390,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1370,9 +1448,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1416,9 +1496,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1462,9 +1544,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)GetByName,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)GetItemName,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)GetItemIndex,
 };
@@ -1496,9 +1580,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)NULL,
 };
@@ -1530,9 +1616,11 @@ static DescriptorContainerDef ContainerDef = {
   (CountMethod)Count,
   (GetByIndexMethod)GetByIndex,
   (GetByNameMethod)NULL,
+  (GetByCamelcaseNameMethod)NULL,
   (GetByNumberMethod)NULL,
   (NewObjectFromItemMethod)NewObjectFromItem,
   (GetItemNameMethod)NULL,
+  (GetItemCamelcaseNameMethod)NULL,
   (GetItemNumberMethod)NULL,
   (GetItemIndexMethod)NULL,
 };
diff --git a/python/google/protobuf/pyext/descriptor_containers.h b/python/google/protobuf/pyext/descriptor_containers.h
index 8fbdaff9..ce40747d 100644
--- a/python/google/protobuf/pyext/descriptor_containers.h
+++ b/python/google/protobuf/pyext/descriptor_containers.h
@@ -54,6 +54,7 @@ bool InitDescriptorMappingTypes();
 
 namespace message_descriptor {
 PyObject* NewMessageFieldsByName(const Descriptor* descriptor);
+PyObject* NewMessageFieldsByCamelcaseName(const Descriptor* descriptor);
 PyObject* NewMessageFieldsByNumber(const Descriptor* descriptor);
 PyObject* NewMessageFieldsSeq(const Descriptor* descriptor);
 
diff --git a/python/google/protobuf/pyext/descriptor_pool.cc b/python/google/protobuf/pyext/descriptor_pool.cc
index 7aed651d..6443a7d5 100644
--- a/python/google/protobuf/pyext/descriptor_pool.cc
+++ b/python/google/protobuf/pyext/descriptor_pool.cc
@@ -108,6 +108,7 @@ static void Dealloc(PyDescriptorPool* self) {
     Py_DECREF(it->second);
   }
   delete self->descriptor_options;
+  delete self->pool;
   delete self->message_factory;
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
@@ -131,22 +132,9 @@ PyObject* FindMessageByName(PyDescriptorPool* self, PyObject* arg) {
 }
 
 // Add a message class to our database.
-const Descriptor* RegisterMessageClass(
-    PyDescriptorPool* self, PyObject *message_class, PyObject* descriptor) {
-  ScopedPyObjectPtr full_message_name(
-      PyObject_GetAttrString(descriptor, "full_name"));
-  Py_ssize_t name_size;
-  char* name;
-  if (PyString_AsStringAndSize(full_message_name, &name, &name_size) < 0) {
-    return NULL;
-  }
-  const Descriptor *message_descriptor =
-      self->pool->FindMessageTypeByName(string(name, name_size));
-  if (!message_descriptor) {
-    PyErr_Format(PyExc_TypeError, "Could not find C++ descriptor for '%s'",
-                 name);
-    return NULL;
-  }
+int RegisterMessageClass(PyDescriptorPool* self,
+                         const Descriptor *message_descriptor,
+                         PyObject *message_class) {
   Py_INCREF(message_class);
   typedef PyDescriptorPool::ClassesByMessageMap::iterator iterator;
   std::pair<iterator, bool> ret = self->classes_by_descriptor->insert(
@@ -156,7 +144,7 @@ const Descriptor* RegisterMessageClass(
     Py_DECREF(ret.first->second);
     ret.first->second = message_class;
   }
-  return message_descriptor;
+  return 0;
 }
 
 // Retrieve the message class added to our database.
@@ -260,6 +248,80 @@ PyObject* FindOneofByName(PyDescriptorPool* self, PyObject* arg) {
   return PyOneofDescriptor_FromDescriptor(oneof_descriptor);
 }
 
+PyObject* FindFileContainingSymbol(PyDescriptorPool* self, PyObject* arg) {
+  Py_ssize_t name_size;
+  char* name;
+  if (PyString_AsStringAndSize(arg, &name, &name_size) < 0) {
+    return NULL;
+  }
+
+  const FileDescriptor* file_descriptor =
+      self->pool->FindFileContainingSymbol(string(name, name_size));
+  if (file_descriptor == NULL) {
+    PyErr_Format(PyExc_KeyError, "Couldn't find symbol %.200s", name);
+    return NULL;
+  }
+
+  return PyFileDescriptor_FromDescriptor(file_descriptor);
+}
+
+// These functions should not exist -- the only valid way to create
+// descriptors is to call Add() or AddSerializedFile().
+// But these AddDescriptor() functions were created in Python and some people
+// call them, so we support them for now for compatibility.
+// However we do check that the existing descriptor already exists in the pool,
+// which appears to always be true for existing calls -- but then why do people
+// call a function that will just be a no-op?
+// TODO(amauryfa): Need to investigate further.
+
+PyObject* AddFileDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+  const FileDescriptor* file_descriptor =
+      PyFileDescriptor_AsDescriptor(descriptor);
+  if (!file_descriptor) {
+    return NULL;
+  }
+  if (file_descriptor !=
+      self->pool->FindFileByName(file_descriptor->name())) {
+    PyErr_Format(PyExc_ValueError,
+                 "The file descriptor %s does not belong to this pool",
+                 file_descriptor->name().c_str());
+    return NULL;
+  }
+  Py_RETURN_NONE;
+}
+
+PyObject* AddDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+  const Descriptor* message_descriptor =
+      PyMessageDescriptor_AsDescriptor(descriptor);
+  if (!message_descriptor) {
+    return NULL;
+  }
+  if (message_descriptor !=
+      self->pool->FindMessageTypeByName(message_descriptor->full_name())) {
+    PyErr_Format(PyExc_ValueError,
+                 "The message descriptor %s does not belong to this pool",
+                 message_descriptor->full_name().c_str());
+    return NULL;
+  }
+  Py_RETURN_NONE;
+}
+
+PyObject* AddEnumDescriptor(PyDescriptorPool* self, PyObject* descriptor) {
+  const EnumDescriptor* enum_descriptor =
+      PyEnumDescriptor_AsDescriptor(descriptor);
+  if (!enum_descriptor) {
+    return NULL;
+  }
+  if (enum_descriptor !=
+      self->pool->FindEnumTypeByName(enum_descriptor->full_name())) {
+    PyErr_Format(PyExc_ValueError,
+                 "The enum descriptor %s does not belong to this pool",
+                 enum_descriptor->full_name().c_str());
+    return NULL;
+  }
+  Py_RETURN_NONE;
+}
+
 // The code below loads new Descriptors from a serialized FileDescriptorProto.
 
 
@@ -341,6 +403,15 @@ static PyMethodDef Methods[] = {
   { "AddSerializedFile", (PyCFunction)AddSerializedFile, METH_O,
     "Adds a serialized FileDescriptorProto to this pool." },
 
+  // TODO(amauryfa): Understand why the Python implementation differs from
+  // this one, ask users to use another API and deprecate these functions.
+  { "AddFileDescriptor", (PyCFunction)AddFileDescriptor, METH_O,
+    "No-op. Add() must have been called before." },
+  { "AddDescriptor", (PyCFunction)AddDescriptor, METH_O,
+    "No-op. Add() must have been called before." },
+  { "AddEnumDescriptor", (PyCFunction)AddEnumDescriptor, METH_O,
+    "No-op. Add() must have been called before." },
+
   { "FindFileByName", (PyCFunction)FindFileByName, METH_O,
     "Searches for a file descriptor by its .proto name." },
   { "FindMessageTypeByName", (PyCFunction)FindMessageByName, METH_O,
@@ -353,6 +424,9 @@ static PyMethodDef Methods[] = {
     "Searches for enum type descriptor by full name." },
   { "FindOneofByName", (PyCFunction)FindOneofByName, METH_O,
     "Searches for oneof descriptor by full name." },
+
+  { "FindFileContainingSymbol", (PyCFunction)FindFileContainingSymbol, METH_O,
+    "Gets the FileDescriptor containing the specified symbol." },
   {NULL}
 };
 
@@ -420,7 +494,7 @@ bool InitDescriptorPool() {
   return true;
 }
 
-PyDescriptorPool* GetDescriptorPool() {
+PyDescriptorPool* GetDefaultDescriptorPool() {
   return python_generated_pool;
 }
 
@@ -432,7 +506,7 @@ PyDescriptorPool* GetDescriptorPool_FromPool(const DescriptorPool* pool) {
   }
   hash_map<const DescriptorPool*, PyDescriptorPool*>::iterator it =
       descriptor_pool_map.find(pool);
-  if (it != descriptor_pool_map.end()) {
+  if (it == descriptor_pool_map.end()) {
     PyErr_SetString(PyExc_KeyError, "Unknown descriptor pool");
     return NULL;
   }
diff --git a/python/google/protobuf/pyext/descriptor_pool.h b/python/google/protobuf/pyext/descriptor_pool.h
index 541d920b..eda73d38 100644
--- a/python/google/protobuf/pyext/descriptor_pool.h
+++ b/python/google/protobuf/pyext/descriptor_pool.h
@@ -89,12 +89,10 @@ const Descriptor* FindMessageTypeByName(PyDescriptorPool* self,
                                         const string& name);
 
 // Registers a new Python class for the given message descriptor.
-// Returns the message Descriptor.
-// On error, returns NULL with a Python exception set.
-const Descriptor* RegisterMessageClass(
-    PyDescriptorPool* self, PyObject* message_class, PyObject* descriptor);
-
-// The function below are also exposed as methods of the DescriptorPool type.
+// On error, returns -1 with a Python exception set.
+int RegisterMessageClass(PyDescriptorPool* self,
+                         const Descriptor* message_descriptor,
+                         PyObject* message_class);
 
 // Retrieves the Python class registered with the given message descriptor.
 //
@@ -103,6 +101,8 @@ const Descriptor* RegisterMessageClass(
 PyObject* GetMessageClass(PyDescriptorPool* self,
                           const Descriptor* message_descriptor);
 
+// The functions below are also exposed as methods of the DescriptorPool type.
+
 // Looks up a message by name. Returns a PyMessageDescriptor corresponding to
 // the field on success, or NULL on failure.
 //
@@ -136,8 +136,9 @@ PyObject* FindOneofByName(PyDescriptorPool* self, PyObject* arg);
 }  // namespace cdescriptor_pool
 
 // Retrieve the global descriptor pool owned by the _message module.
+// This is the one used by pb2.py generated modules.
 // Returns a *borrowed* reference.
-PyDescriptorPool* GetDescriptorPool();
+PyDescriptorPool* GetDefaultDescriptorPool();
 
 // Retrieve the python descriptor pool owning a C++ descriptor pool.
 // Returns a *borrowed* reference.
diff --git a/python/google/protobuf/pyext/extension_dict.cc b/python/google/protobuf/pyext/extension_dict.cc
index 8ebbb27c..9c9b4178 100644
--- a/python/google/protobuf/pyext/extension_dict.cc
+++ b/python/google/protobuf/pyext/extension_dict.cc
@@ -123,7 +123,8 @@ PyObject* subscript(ExtensionDict* self, PyObject* key) {
   if (descriptor->label() == FieldDescriptor::LABEL_REPEATED) {
     if (descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       PyObject *message_class = cdescriptor_pool::GetMessageClass(
-          GetDescriptorPool(), descriptor->message_type());
+          cmessage::GetDescriptorPoolForMessage(self->parent),
+          descriptor->message_type());
       if (message_class == NULL) {
         return NULL;
       }
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index 62c7c478..63d53136 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -55,6 +55,7 @@
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/message.h>
 #include <google/protobuf/text_format.h>
+#include <google/protobuf/unknown_field_set.h>
 #include <google/protobuf/pyext/descriptor.h>
 #include <google/protobuf/pyext/descriptor_pool.h>
 #include <google/protobuf/pyext/extension_dict.h>
@@ -107,8 +108,18 @@ struct PyMessageMeta {
 
   // C++ descriptor of this message.
   const Descriptor* message_descriptor;
+
   // Owned reference, used to keep the pointer above alive.
   PyObject* py_message_descriptor;
+
+  // The Python DescriptorPool used to create the class. It is needed to resolve
+  // fields descriptors, including extensions fields; its C++ MessageFactory is
+  // used to instantiate submessages.
+  // This can be different from DESCRIPTOR.file.pool, in the case of a custom
+  // DescriptorPool which defines new extensions.
+  // We own the reference, because it's important to keep the descriptors and
+  // factory alive.
+  PyDescriptorPool* py_descriptor_pool;
 };
 
 namespace message_meta {
@@ -139,18 +150,10 @@ static bool AddFieldNumberToClass(
 
 
 // Finalize the creation of the Message class.
-// Called from its metaclass: GeneratedProtocolMessageType.__init__().
-static int AddDescriptors(PyObject* cls, PyObject* descriptor) {
-  const Descriptor* message_descriptor =
-      cdescriptor_pool::RegisterMessageClass(
-          GetDescriptorPool(), cls, descriptor);
-  if (message_descriptor == NULL) {
-    return -1;
-  }
-
+static int AddDescriptors(PyObject* cls, const Descriptor* descriptor) {
   // If there are extension_ranges, the message is "extendable", and extension
   // classes will register themselves in this class.
-  if (message_descriptor->extension_range_count() > 0) {
+  if (descriptor->extension_range_count() > 0) {
     ScopedPyObjectPtr by_name(PyDict_New());
     if (PyObject_SetAttr(cls, k_extensions_by_name, by_name) < 0) {
       return -1;
@@ -162,8 +165,8 @@ static int AddDescriptors(PyObject* cls, PyObject* descriptor) {
   }
 
   // For each field set: cls.<field>_FIELD_NUMBER = <number>
-  for (int i = 0; i < message_descriptor->field_count(); ++i) {
-    if (!AddFieldNumberToClass(cls, message_descriptor->field(i))) {
+  for (int i = 0; i < descriptor->field_count(); ++i) {
+    if (!AddFieldNumberToClass(cls, descriptor->field(i))) {
       return -1;
     }
   }
@@ -173,8 +176,8 @@ static int AddDescriptors(PyObject* cls, PyObject* descriptor) {
   // The enum descriptor we get from
   // <messagedescriptor>.enum_types_by_name[name]
   // which was built previously.
-  for (int i = 0; i < message_descriptor->enum_type_count(); ++i) {
-    const EnumDescriptor* enum_descriptor = message_descriptor->enum_type(i);
+  for (int i = 0; i < descriptor->enum_type_count(); ++i) {
+    const EnumDescriptor* enum_descriptor = descriptor->enum_type(i);
     ScopedPyObjectPtr enum_type(
         PyEnumDescriptor_FromDescriptor(enum_descriptor));
     if (enum_type == NULL) {
@@ -212,8 +215,8 @@ static int AddDescriptors(PyObject* cls, PyObject* descriptor) {
   // Extension descriptors come from
   // <message descriptor>.extensions_by_name[name]
   // which was defined previously.
-  for (int i = 0; i < message_descriptor->extension_count(); ++i) {
-    const google::protobuf::FieldDescriptor* field = message_descriptor->extension(i);
+  for (int i = 0; i < descriptor->extension_count(); ++i) {
+    const google::protobuf::FieldDescriptor* field = descriptor->extension(i);
     ScopedPyObjectPtr extension_field(PyFieldDescriptor_FromDescriptor(field));
     if (extension_field == NULL) {
       return -1;
@@ -258,14 +261,14 @@ static PyObject* New(PyTypeObject* type,
   }
 
   // Check dict['DESCRIPTOR']
-  PyObject* descriptor = PyDict_GetItem(dict, kDESCRIPTOR);
-  if (descriptor == NULL) {
+  PyObject* py_descriptor = PyDict_GetItem(dict, kDESCRIPTOR);
+  if (py_descriptor == NULL) {
     PyErr_SetString(PyExc_TypeError, "Message class has no DESCRIPTOR");
     return NULL;
   }
-  if (!PyObject_TypeCheck(descriptor, &PyMessageDescriptor_Type)) {
+  if (!PyObject_TypeCheck(py_descriptor, &PyMessageDescriptor_Type)) {
     PyErr_Format(PyExc_TypeError, "Expected a message Descriptor, got %s",
-                 descriptor->ob_type->tp_name);
+                 py_descriptor->ob_type->tp_name);
     return NULL;
   }
 
@@ -291,14 +294,28 @@ static PyObject* New(PyTypeObject* type,
   }
 
   // Cache the descriptor, both as Python object and as C++ pointer.
-  const Descriptor* message_descriptor =
-      PyMessageDescriptor_AsDescriptor(descriptor);
-  if (message_descriptor == NULL) {
+  const Descriptor* descriptor =
+      PyMessageDescriptor_AsDescriptor(py_descriptor);
+  if (descriptor == NULL) {
+    return NULL;
+  }
+  Py_INCREF(py_descriptor);
+  newtype->py_message_descriptor = py_descriptor;
+  newtype->message_descriptor = descriptor;
+  // TODO(amauryfa): Don't always use the canonical pool of the descriptor,
+  // use the MessageFactory optionally passed in the class dict.
+  newtype->py_descriptor_pool = GetDescriptorPool_FromPool(
+      descriptor->file()->pool());
+  if (newtype->py_descriptor_pool == NULL) {
+    return NULL;
+  }
+  Py_INCREF(newtype->py_descriptor_pool);
+
+  // Add the message to the DescriptorPool.
+  if (cdescriptor_pool::RegisterMessageClass(newtype->py_descriptor_pool,
+                                             descriptor, result) < 0) {
     return NULL;
   }
-  Py_INCREF(descriptor);
-  newtype->py_message_descriptor = descriptor;
-  newtype->message_descriptor = message_descriptor;
 
   // Continue with type initialization: add other descriptors, enum values...
   if (AddDescriptors(result, descriptor) < 0) {
@@ -309,6 +326,7 @@ static PyObject* New(PyTypeObject* type,
 
 static void Dealloc(PyMessageMeta *self) {
   Py_DECREF(self->py_message_descriptor);
+  Py_DECREF(self->py_descriptor_pool);
   Py_TYPE(self)->tp_free(reinterpret_cast<PyObject*>(self));
 }
 
@@ -381,12 +399,20 @@ PyTypeObject PyMessageMeta_Type = {
   message_meta::New,                   // tp_new
 };
 
-static const Descriptor* GetMessageDescriptor(PyTypeObject* cls) {
+static PyMessageMeta* CheckMessageClass(PyTypeObject* cls) {
   if (!PyObject_TypeCheck(cls, &PyMessageMeta_Type)) {
     PyErr_Format(PyExc_TypeError, "Class %s is not a Message", cls->tp_name);
     return NULL;
   }
-  return reinterpret_cast<PyMessageMeta*>(cls)->message_descriptor;
+  return reinterpret_cast<PyMessageMeta*>(cls);
+}
+
+static const Descriptor* GetMessageDescriptor(PyTypeObject* cls) {
+  PyMessageMeta* type = CheckMessageClass(cls);
+  if (type == NULL) {
+    return NULL;
+  }
+  return type->message_descriptor;
 }
 
 // Forward declarations
@@ -723,6 +749,17 @@ bool CheckFieldBelongsToMessage(const FieldDescriptor* field_descriptor,
 
 namespace cmessage {
 
+PyDescriptorPool* GetDescriptorPoolForMessage(CMessage* message) {
+  // No need to check the type: the type of instances of CMessage is always
+  // an instance of PyMessageMeta. Let's prove it with a debug-only check.
+  GOOGLE_DCHECK(PyObject_TypeCheck(message, &CMessage_Type));
+  return reinterpret_cast<PyMessageMeta*>(Py_TYPE(message))->py_descriptor_pool;
+}
+
+MessageFactory* GetFactoryForMessage(CMessage* message) {
+  return GetDescriptorPoolForMessage(message)->message_factory;
+}
+
 static int MaybeReleaseOverlappingOneofField(
     CMessage* cmessage,
     const FieldDescriptor* field) {
@@ -773,7 +810,7 @@ static Message* GetMutableMessage(
     return NULL;
   }
   return reflection->MutableMessage(
-      parent_message, parent_field, GetDescriptorPool()->message_factory);
+      parent_message, parent_field, GetFactoryForMessage(parent));
 }
 
 struct FixupMessageReference : public ChildVisitor {
@@ -814,10 +851,7 @@ int AssureWritable(CMessage* self) {
     // If parent is NULL but we are trying to modify a read-only message, this
     // is a reference to a constant default instance that needs to be replaced
     // with a mutable top-level message.
-    const Message* prototype =
-        GetDescriptorPool()->message_factory->GetPrototype(
-            self->message->GetDescriptor());
-    self->message = prototype->New();
+    self->message = self->message->New();
     self->owner.reset(self->message);
     // Cascade the new owner to eventual children: even if this message is
     // empty, some submessages or repeated containers might exist already.
@@ -1190,15 +1224,19 @@ CMessage* NewEmptyMessage(PyObject* type, const Descriptor *descriptor) {
 
 // The __new__ method of Message classes.
 // Creates a new C++ message and takes ownership.
-static PyObject* New(PyTypeObject* type,
+static PyObject* New(PyTypeObject* cls,
                      PyObject* unused_args, PyObject* unused_kwargs) {
+  PyMessageMeta* type = CheckMessageClass(cls);
+  if (type == NULL) {
+    return NULL;
+  }
   // Retrieve the message descriptor and the default instance (=prototype).
-  const Descriptor* message_descriptor = GetMessageDescriptor(type);
+  const Descriptor* message_descriptor = type->message_descriptor;
   if (message_descriptor == NULL) {
     return NULL;
   }
-  const Message* default_message =
-      GetDescriptorPool()->message_factory->GetPrototype(message_descriptor);
+  const Message* default_message = type->py_descriptor_pool->message_factory
+                                   ->GetPrototype(message_descriptor);
   if (default_message == NULL) {
     PyErr_SetString(PyExc_TypeError, message_descriptor->full_name().c_str());
     return NULL;
@@ -1528,7 +1566,7 @@ int SetOwner(CMessage* self, const shared_ptr<Message>& new_owner) {
 Message* ReleaseMessage(CMessage* self,
                         const Descriptor* descriptor,
                         const FieldDescriptor* field_descriptor) {
-  MessageFactory* message_factory = GetDescriptorPool()->message_factory;
+  MessageFactory* message_factory = GetFactoryForMessage(self);
   Message* released_message = self->message->GetReflection()->ReleaseMessage(
       self->message, field_descriptor, message_factory);
   // ReleaseMessage will return NULL which differs from
@@ -1883,8 +1921,8 @@ static PyObject* MergeFromString(CMessage* self, PyObject* arg) {
   AssureWritable(self);
   io::CodedInputStream input(
       reinterpret_cast<const uint8*>(data), data_length);
-  input.SetExtensionRegistry(GetDescriptorPool()->pool,
-                             GetDescriptorPool()->message_factory);
+  PyDescriptorPool* pool = GetDescriptorPoolForMessage(self);
+  input.SetExtensionRegistry(pool->pool, pool->message_factory);
   bool success = self->message->MergePartialFromCodedStream(&input);
   if (success) {
     return PyInt_FromLong(input.CurrentPosition());
@@ -1907,11 +1945,6 @@ static PyObject* ByteSize(CMessage* self, PyObject* args) {
 
 static PyObject* RegisterExtension(PyObject* cls,
                                    PyObject* extension_handle) {
-  ScopedPyObjectPtr message_descriptor(PyObject_GetAttr(cls, kDESCRIPTOR));
-  if (message_descriptor == NULL) {
-    return NULL;
-  }
-
   const FieldDescriptor* descriptor =
       GetExtensionDescriptor(extension_handle);
   if (descriptor == NULL) {
@@ -1920,13 +1953,6 @@ static PyObject* RegisterExtension(PyObject* cls,
   const Descriptor* cmessage_descriptor = GetMessageDescriptor(
       reinterpret_cast<PyTypeObject*>(cls));
 
-  if (cmessage_descriptor != descriptor->containing_type()) {
-    if (PyObject_SetAttrString(extension_handle, "containing_type",
-                               message_descriptor) < 0) {
-      return NULL;
-    }
-  }
-
   ScopedPyObjectPtr extensions_by_name(
       PyObject_GetAttr(cls, k_extensions_by_name));
   if (extensions_by_name == NULL) {
@@ -2050,7 +2076,8 @@ static PyObject* ListFields(CMessage* self) {
       // TODO(amauryfa): consider building the class on the fly!
       if (fields[i]->message_type() != NULL &&
           cdescriptor_pool::GetMessageClass(
-              GetDescriptorPool(), fields[i]->message_type()) == NULL) {
+              GetDescriptorPoolForMessage(self),
+              fields[i]->message_type()) == NULL) {
         PyErr_Clear();
         continue;
       }
@@ -2207,7 +2234,9 @@ PyObject* InternalGetScalar(const Message* message,
             message->GetReflection()->GetUnknownFields(*message);
         for (int i = 0; i < unknown_field_set.field_count(); ++i) {
           if (unknown_field_set.field(i).number() ==
-              field_descriptor->number()) {
+              field_descriptor->number() &&
+              unknown_field_set.field(i).type() ==
+              google::protobuf::UnknownField::TYPE_VARINT) {
             result = PyInt_FromLong(unknown_field_set.field(i).varint());
             break;
           }
@@ -2233,11 +2262,12 @@ PyObject* InternalGetScalar(const Message* message,
 PyObject* InternalGetSubMessage(
     CMessage* self, const FieldDescriptor* field_descriptor) {
   const Reflection* reflection = self->message->GetReflection();
+  PyDescriptorPool* pool = GetDescriptorPoolForMessage(self);
   const Message& sub_message = reflection->GetMessage(
-      *self->message, field_descriptor, GetDescriptorPool()->message_factory);
+      *self->message, field_descriptor, pool->message_factory);
 
   PyObject *message_class = cdescriptor_pool::GetMessageClass(
-      GetDescriptorPool(), field_descriptor->message_type());
+      pool, field_descriptor->message_type());
   if (message_class == NULL) {
     return NULL;
   }
@@ -2560,7 +2590,7 @@ PyObject* GetAttr(CMessage* self, PyObject* name) {
     const FieldDescriptor* value_type = entry_type->FindFieldByName("value");
     if (value_type->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       PyObject* value_class = cdescriptor_pool::GetMessageClass(
-          GetDescriptorPool(), value_type->message_type());
+          GetDescriptorPoolForMessage(self), value_type->message_type());
       if (value_class == NULL) {
         return NULL;
       }
@@ -2583,7 +2613,7 @@ PyObject* GetAttr(CMessage* self, PyObject* name) {
     PyObject* py_container = NULL;
     if (field_descriptor->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       PyObject *message_class = cdescriptor_pool::GetMessageClass(
-          GetDescriptorPool(), field_descriptor->message_type());
+          GetDescriptorPoolForMessage(self), field_descriptor->message_type());
       if (message_class == NULL) {
         return NULL;
       }
@@ -2908,9 +2938,10 @@ bool InitProto2MessageModule(PyObject *m) {
 
   // Expose the DescriptorPool used to hold all descriptors added from generated
   // pb2.py files.
-  Py_INCREF(GetDescriptorPool());  // PyModule_AddObject steals a reference.
-  PyModule_AddObject(
-      m, "default_pool", reinterpret_cast<PyObject*>(GetDescriptorPool()));
+  // PyModule_AddObject steals a reference.
+  Py_INCREF(GetDefaultDescriptorPool());
+  PyModule_AddObject(m, "default_pool",
+                     reinterpret_cast<PyObject*>(GetDefaultDescriptorPool()));
 
   // This implementation provides full Descriptor types, we advertise it so that
   // descriptor.py can use them in replacement of the Python classes.
diff --git a/python/google/protobuf/pyext/message.h b/python/google/protobuf/pyext/message.h
index f147d433..1ff82e2f 100644
--- a/python/google/protobuf/pyext/message.h
+++ b/python/google/protobuf/pyext/message.h
@@ -49,12 +49,15 @@ class Message;
 class Reflection;
 class FieldDescriptor;
 class Descriptor;
+class DescriptorPool;
+class MessageFactory;
 
 using internal::shared_ptr;
 
 namespace python {
 
 struct ExtensionDict;
+struct PyDescriptorPool;
 
 typedef struct CMessage {
   PyObject_HEAD;
@@ -220,6 +223,16 @@ PyObject* FindInitializationErrors(CMessage* self);
 int SetOwner(CMessage* self, const shared_ptr<Message>& new_owner);
 
 int AssureWritable(CMessage* self);
+
+// Returns the "best" DescriptorPool for the given message.
+// This is often equivalent to message.DESCRIPTOR.pool, but not always, when
+// the message class was created from a MessageFactory using a custom pool which
+// uses the generated pool as an underlay.
+//
+// The returned pool is suitable for finding fields and building submessages,
+// even in the case of extensions.
+PyDescriptorPool* GetDescriptorPoolForMessage(CMessage* message);
+
 }  // namespace cmessage
 
 
diff --git a/python/google/protobuf/symbol_database.py b/python/google/protobuf/symbol_database.py
index 4c70b393..b81ef4d7 100644
--- a/python/google/protobuf/symbol_database.py
+++ b/python/google/protobuf/symbol_database.py
@@ -60,6 +60,7 @@ Example usage:
 """
 
 
+from google.protobuf import descriptor as _descriptor
 from google.protobuf import descriptor_pool
 
 
@@ -72,6 +73,31 @@ class SymbolDatabase(object):
   buffer types used within a program.
   """
 
+  # pylint: disable=protected-access
+  if _descriptor._USE_C_DESCRIPTORS:
+
+    def __new__(cls):
+      raise TypeError("Instances of SymbolDatabase cannot be created")
+
+    @classmethod
+    def _CreateDefaultDatabase(cls):
+      self = object.__new__(cls)  # Bypass the __new__ above.
+      # Don't call __init__() and initialize here.
+      self._symbols = {}
+      self._symbols_by_file = {}
+      # As of today all descriptors are registered and retrieved from
+      # _message.default_pool (see FileDescriptor.__new__), so it's not
+      # necessary to use another pool.
+      self.pool = _descriptor._message.default_pool
+      return self
+  # pylint: enable=protected-access
+
+  else:
+
+    @classmethod
+    def _CreateDefaultDatabase(cls):
+      return cls()
+
   def __init__(self):
     """Constructor."""
 
@@ -177,7 +203,7 @@ class SymbolDatabase(object):
       result.update(self._symbols_by_file[f])
     return result
 
-_DEFAULT = SymbolDatabase()
+_DEFAULT = SymbolDatabase._CreateDefaultDatabase()
 
 
 def Default():
diff --git a/python/google/protobuf/text_encoding.py b/python/google/protobuf/text_encoding.py
index a0728e3c..98995638 100644
--- a/python/google/protobuf/text_encoding.py
+++ b/python/google/protobuf/text_encoding.py
@@ -27,6 +27,7 @@
 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
 """Encoding related utilities."""
 import re
 
diff --git a/python/google/protobuf/text_format.py b/python/google/protobuf/text_format.py
index 1399223f..e4fadf09 100755
--- a/python/google/protobuf/text_format.py
+++ b/python/google/protobuf/text_format.py
@@ -28,9 +28,17 @@
 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-# Copyright 2007 Google Inc. All Rights Reserved.
+"""Contains routines for printing protocol messages in text format.
 
-"""Contains routines for printing protocol messages in text format."""
+Simple usage example:
+
+  # Create a proto object and serialize it to a text proto string.
+  message = my_proto_pb2.MyMessage(foo='bar')
+  text_proto = text_format.MessageToString(message)
+
+  # Parse a text proto string.
+  message = text_format.Parse(text_proto, my_proto_pb2.MyMessage())
+"""
 
 __author__ = 'kenton@google.com (Kenton Varda)'
 
diff --git a/python/google/protobuf/util/__init__.py b/python/google/protobuf/util/__init__.py
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/python/google/protobuf/util/__init__.py
diff --git a/python/setup.py b/python/setup.py
index 8269c4a5..a7bc6cd6 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -88,6 +88,15 @@ def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/unittest_mset_wire_format.proto", False)
   generate_proto("../src/google/protobuf/unittest_no_generic_services.proto", False)
   generate_proto("../src/google/protobuf/unittest_proto3_arena.proto", False)
+  # Move the well-known-types proto to required when they are no longer only
+  # required by json format tests.
+  generate_proto("../src/google/protobuf/timestamp.proto", False)
+  generate_proto("../src/google/protobuf/duration.proto", False)
+  generate_proto("../src/google/protobuf/wrappers.proto", False)
+  generate_proto("../src/google/protobuf/struct.proto", False)
+  generate_proto("../src/google/protobuf/any.proto", False)
+  generate_proto("../src/google/protobuf/field_mask.proto", False)
+  generate_proto("../src/google/protobuf/util/json_format_proto3.proto", False)
   generate_proto("google/protobuf/internal/descriptor_pool_test1.proto", False)
   generate_proto("google/protobuf/internal/descriptor_pool_test2.proto", False)
   generate_proto("google/protobuf/internal/factory_test1.proto", False)
diff --git a/src/google/protobuf/any.cc b/src/google/protobuf/any.cc
index c6ed37ae..7351d377 100644
--- a/src/google/protobuf/any.cc
+++ b/src/google/protobuf/any.cc
@@ -43,6 +43,7 @@ string GetTypeUrl(const Descriptor* message) {
 
 const char kAnyFullTypeName[] = "google.protobuf.Any";
 const char kTypeGoogleApisComPrefix[] = "type.googleapis.com/";
+const char kTypeGoogleProdComPrefix[] = "type.googleprod.com/";
 
 AnyMetadata::AnyMetadata(UrlType* type_url, ValueType* value)
     : type_url_(type_url), value_(value) {
@@ -70,11 +71,17 @@ bool AnyMetadata::InternalIs(const Descriptor* descriptor) const {
 }
 
 bool ParseAnyTypeUrl(const string& type_url, string* full_type_name) {
-  const int prefix_len = strlen(kTypeGoogleApisComPrefix);
-  if (strncmp(type_url.c_str(), kTypeGoogleApisComPrefix, prefix_len) == 0) {
-    full_type_name->assign(type_url.data() + prefix_len,
-                           type_url.size() - prefix_len);
-    return true;
+  static const char* prefix[] = {
+    kTypeGoogleApisComPrefix,
+    kTypeGoogleProdComPrefix
+  };
+  for (int i = 0; i < 2; i++) {
+    const int prefix_len = strlen(prefix[i]);
+    if (strncmp(type_url.c_str(), prefix[i], prefix_len) == 0) {
+      full_type_name->assign(type_url.data() + prefix_len,
+                             type_url.size() - prefix_len);
+      return true;
+    }
   }
   return false;
 }
diff --git a/src/google/protobuf/any.h b/src/google/protobuf/any.h
index 7eeb6b70..f760ad5d 100644
--- a/src/google/protobuf/any.h
+++ b/src/google/protobuf/any.h
@@ -70,6 +70,7 @@ class LIBPROTOBUF_EXPORT AnyMetadata {
 
 extern const char kAnyFullTypeName[];          // "google.protobuf.Any".
 extern const char kTypeGoogleApisComPrefix[];  // "type.googleapis.com/".
+extern const char kTypeGoogleProdComPrefix[];  // "type.googleprod.com/".
 
 // Get the proto type name from Any::type_url value. For example, passing
 // "type.googleapis.com/rpc.QueryOrigin" will return "rpc.QueryOrigin" in
diff --git a/src/google/protobuf/arena.cc b/src/google/protobuf/arena.cc
index 907a6a20..74b09655 100755
--- a/src/google/protobuf/arena.cc
+++ b/src/google/protobuf/arena.cc
@@ -38,17 +38,17 @@ namespace google {
 namespace protobuf {
 
 google::protobuf::internal::SequenceNumber Arena::lifecycle_id_generator_;
-#ifdef PROTOBUF_USE_DLLS
-Arena::ThreadCache& Arena::thread_cache() {
-  static GOOGLE_THREAD_LOCAL ThreadCache thread_cache_ = { -1, NULL };
-  return thread_cache_;
-}
-#elif defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)
+#if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)
 Arena::ThreadCache& Arena::thread_cache() {
   static internal::ThreadLocalStorage<ThreadCache>* thread_cache_ =
       new internal::ThreadLocalStorage<ThreadCache>();
   return *thread_cache_->Get();
 }
+#elif defined(PROTOBUF_USE_DLLS)
+Arena::ThreadCache& Arena::thread_cache() {
+  static GOOGLE_THREAD_LOCAL ThreadCache thread_cache_ = { -1, NULL };
+  return thread_cache_;
+}
 #else
 GOOGLE_THREAD_LOCAL Arena::ThreadCache Arena::thread_cache_ = { -1, NULL };
 #endif
diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h
index 074a9e54..16e0d50e 100644
--- a/src/google/protobuf/arena.h
+++ b/src/google/protobuf/arena.h
@@ -38,7 +38,16 @@
 #if __cplusplus >= 201103L
 #include <google/protobuf/stubs/type_traits.h>
 #endif
+#if defined(_MSC_VER) && !_HAS_EXCEPTIONS
+// Work around bugs in MSVC <typeinfo> header when _HAS_EXCEPTIONS=0.
+#include <exception>
 #include <typeinfo>
+namespace std {
+using type_info = ::type_info;
+}
+#else
+#include <typeinfo>
+#endif
 
 #include <google/protobuf/stubs/atomic_sequence_num.h>
 #include <google/protobuf/stubs/atomicops.h>
@@ -533,15 +542,15 @@ class LIBPROTOBUF_EXPORT Arena {
 
   static const size_t kHeaderSize = sizeof(Block);
   static google::protobuf::internal::SequenceNumber lifecycle_id_generator_;
-#ifdef PROTOBUF_USE_DLLS
-  // Thread local variables cannot be exposed through DLL interface but we can
-  // wrap them in static functions.
-  static ThreadCache& thread_cache();
-#elif defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)
+#if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)
   // Android ndk does not support GOOGLE_THREAD_LOCAL keyword so we use a custom thread
   // local storage class we implemented.
   // iOS also does not support the GOOGLE_THREAD_LOCAL keyword.
   static ThreadCache& thread_cache();
+#elif defined(PROTOBUF_USE_DLLS)
+  // Thread local variables cannot be exposed through DLL interface but we can
+  // wrap them in static functions.
+  static ThreadCache& thread_cache();
 #else
   static GOOGLE_THREAD_LOCAL ThreadCache thread_cache_;
   static ThreadCache& thread_cache() { return thread_cache_; }
@@ -581,11 +590,13 @@ class LIBPROTOBUF_EXPORT Arena {
     template<typename U>
     static double DestructorSkippable(...);
 
+    // The raw_skippable_value const bool variable is separated from the typedef
+    // line below as a work-around of an NVCC 7.0 (and earlier) compiler bug.
+    static const bool raw_skippable_value =
+          sizeof(DestructorSkippable<const T>(static_cast<const T*>(0))) ==
+          sizeof(char) || google::protobuf::internal::has_trivial_destructor<T>::value == true;
     // This will resolve to either google::protobuf::internal::true_type or google::protobuf::internal::false_type.
-    typedef google::protobuf::internal::integral_constant<bool,
-              sizeof(DestructorSkippable<const T>(static_cast<const T*>(0))) ==
-              sizeof(char) || google::protobuf::internal::has_trivial_destructor<T>::value == true>
-              type;
+    typedef google::protobuf::internal::integral_constant<bool, raw_skippable_value> type;
     static const type value;
   };
 
diff --git a/src/google/protobuf/arena_unittest.cc b/src/google/protobuf/arena_unittest.cc
index c9ca1fd1..6b67f446 100644
--- a/src/google/protobuf/arena_unittest.cc
+++ b/src/google/protobuf/arena_unittest.cc
@@ -362,7 +362,7 @@ TEST(ArenaTest, ReleaseMessage) {
   Arena arena;
   TestAllTypes* arena_message = Arena::CreateMessage<TestAllTypes>(&arena);
   arena_message->mutable_optional_nested_message()->set_bb(118);
-  scoped_ptr<TestAllTypes::NestedMessage> nested(
+  google::protobuf::scoped_ptr<TestAllTypes::NestedMessage> nested(
       arena_message->release_optional_nested_message());
   EXPECT_EQ(118, nested->bb());
 
@@ -383,7 +383,7 @@ TEST(ArenaTest, ReleaseString) {
   Arena arena;
   TestAllTypes* arena_message = Arena::CreateMessage<TestAllTypes>(&arena);
   arena_message->set_optional_string("hello");
-  scoped_ptr<string> released_str(
+  google::protobuf::scoped_ptr<string> released_str(
       arena_message->release_optional_string());
   EXPECT_EQ("hello", *released_str);
 
diff --git a/src/google/protobuf/compiler/command_line_interface_unittest.cc b/src/google/protobuf/compiler/command_line_interface_unittest.cc
index 9560d0e0..46ea5c4e 100644
--- a/src/google/protobuf/compiler/command_line_interface_unittest.cc
+++ b/src/google/protobuf/compiler/command_line_interface_unittest.cc
@@ -63,13 +63,13 @@
 #include <google/protobuf/testing/googletest.h>
 #include <gtest/gtest.h>
 
-namespace google {
-namespace protobuf {
-namespace compiler {
 
 // Disable the whole test when we use tcmalloc for "draconian" heap checks, in
 // which case tcmalloc will print warnings that fail the plugin tests.
 #if !GOOGLE_PROTOBUF_HEAP_CHECK_DRACONIAN
+namespace google {
+namespace protobuf {
+namespace compiler {
 
 #if defined(_WIN32)
 #ifndef STDIN_FILENO
@@ -1800,8 +1800,8 @@ TEST_F(EncodeDecodeTest, ProtoParseError) {
 
 }  // anonymous namespace
 
-#endif  // !GOOGLE_PROTOBUF_HEAP_CHECK_DRACONIAN
-
 }  // namespace compiler
 }  // namespace protobuf
+
+#endif  // !GOOGLE_PROTOBUF_HEAP_CHECK_DRACONIAN
 }  // namespace google
diff --git a/src/google/protobuf/compiler/cpp/cpp_map_field.cc b/src/google/protobuf/compiler/cpp/cpp_map_field.cc
index 25acc61b..e5e2f07d 100644
--- a/src/google/protobuf/compiler/cpp/cpp_map_field.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_map_field.cc
@@ -66,7 +66,7 @@ void SetMessageVariables(const FieldDescriptor* descriptor,
       (*variables)["wrapper"] = "EntryWrapper";
       break;
     case FieldDescriptor::CPPTYPE_ENUM:
-      (*variables)["val_cpp"] = ClassName(val->enum_type(), false);
+      (*variables)["val_cpp"] = ClassName(val->enum_type(), true);
       (*variables)["wrapper"] = "EnumEntryWrapper";
       break;
     default:
@@ -200,7 +200,7 @@ GenerateMergeFromCodedStream(io::Printer* printer) const {
       case FieldDescriptor::CPPTYPE_ENUM:
         printer->Print(variables_,
             "(*mutable_$name$())[entry->key()] =\n"
-            "    static_cast<$val_cpp$>(*entry->mutable_value());\n");
+            "    static_cast< $val_cpp$ >(*entry->mutable_value());\n");
         break;
       default:
         printer->Print(variables_,
@@ -215,7 +215,7 @@ GenerateMergeFromCodedStream(io::Printer* printer) const {
         "  DO_(entry->ParseFromString(data));\n"
         "  if ($val_cpp$_IsValid(*entry->mutable_value())) {\n"
         "    (*mutable_$name$())[entry->key()] =\n"
-        "        static_cast<$val_cpp$>(*entry->mutable_value());\n"
+        "        static_cast< $val_cpp$ >(*entry->mutable_value());\n"
         "  } else {\n");
     if (HasDescriptorMethods(descriptor_->file())) {
       printer->Print(variables_,
diff --git a/src/google/protobuf/compiler/cpp/cpp_message.cc b/src/google/protobuf/compiler/cpp/cpp_message.cc
index fc1ce962..8cc8c7ba 100644
--- a/src/google/protobuf/compiler/cpp/cpp_message.cc
+++ b/src/google/protobuf/compiler/cpp/cpp_message.cc
@@ -350,7 +350,7 @@ void CollectMapInfo(const Descriptor* descriptor,
       (*variables)["val"] = FieldMessageTypeName(val);
       break;
     case FieldDescriptor::CPPTYPE_ENUM:
-      (*variables)["val"] = ClassName(val->enum_type(), false);
+      (*variables)["val"] = ClassName(val->enum_type(), true);
       break;
     default:
       (*variables)["val"] = PrimitiveTypeName(val->cpp_type());
diff --git a/src/google/protobuf/compiler/java/java_enum_field_lite.cc b/src/google/protobuf/compiler/java/java_enum_field_lite.cc
index 2c3608c2..e8bf15d0 100644
--- a/src/google/protobuf/compiler/java/java_enum_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_enum_field_lite.cc
@@ -299,7 +299,7 @@ GenerateParsingCode(io::Printer* printer) const {
       "if (value == null) {\n");
     if (PreserveUnknownFields(descriptor_->containing_type())) {
       printer->Print(variables_,
-        "  unknownFields.mergeVarintField($number$, rawValue);\n");
+        "  super.mergeVarintField($number$, rawValue);\n");
     }
     printer->Print(variables_,
       "} else {\n"
@@ -492,7 +492,7 @@ GenerateParsingCode(io::Printer* printer) const {
       "if (value == null) {\n");
     if (PreserveUnknownFields(descriptor_->containing_type())) {
       printer->Print(variables_,
-        "  unknownFields.mergeVarintField($number$, rawValue);\n");
+        "  super.mergeVarintField($number$, rawValue);\n");
     }
     printer->Print(variables_,
       "} else {\n"
@@ -850,7 +850,7 @@ GenerateParsingCode(io::Printer* printer) const {
         "if (value == null) {\n");
     if (PreserveUnknownFields(descriptor_->containing_type())) {
       printer->Print(variables_,
-        "  unknownFields.mergeVarintField($number$, rawValue);\n");
+        "  super.mergeVarintField($number$, rawValue);\n");
     }
     printer->Print(variables_,
       "} else {\n"
diff --git a/src/google/protobuf/compiler/java/java_map_field_lite.cc b/src/google/protobuf/compiler/java/java_map_field_lite.cc
index 4fe656d3..d2039403 100644
--- a/src/google/protobuf/compiler/java/java_map_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_map_field_lite.cc
@@ -405,7 +405,7 @@ GenerateParsingCode(io::Printer* printer) const {
     printer->Print(
         variables_,
         "if ($value_enum_type$.valueOf($name$.getValue()) == null) {\n"
-        "  unknownFields.mergeLengthDelimitedField($number$, bytes);\n"
+        "  super.mergeLengthDelimitedField($number$, bytes);\n"
         "} else {\n"
         "  $name$_.getMutableMap().put($name$.getKey(), $name$.getValue());\n"
         "}\n");
diff --git a/src/google/protobuf/compiler/java/java_message_lite.cc b/src/google/protobuf/compiler/java/java_message_lite.cc
index 8b6c75b8..94ed2c39 100644
--- a/src/google/protobuf/compiler/java/java_message_lite.cc
+++ b/src/google/protobuf/compiler/java/java_message_lite.cc
@@ -1029,12 +1029,6 @@ GenerateParsingConstructor(io::Printer* printer) {
       "bit_field_name", GetBitFieldName(i));
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
-    printer->Print(
-      "com.google.protobuf.UnknownFieldSetLite.Builder unknownFields =\n"
-      "    com.google.protobuf.UnknownFieldSetLite.newBuilder();\n");
-  }
-
   printer->Print(
       "try {\n");
   printer->Indent();
@@ -1056,13 +1050,10 @@ GenerateParsingConstructor(io::Printer* printer) {
 
   if (PreserveUnknownFields(descriptor_)) {
     if (descriptor_->extension_range_count() > 0) {
-      // Lite runtime directly invokes parseUnknownField to reduce method
-      // counts.
       printer->Print(
         "default: {\n"
-        "  if (!parseUnknownField(extensions, getDefaultInstanceForType(),\n"
-        "                         input, unknownFields,\n"
-        "                         extensionRegistry, tag)) {\n"
+        "  if (!parseUnknownField(getDefaultInstanceForType(),\n"
+        "                         input, extensionRegistry, tag)) {\n"
         "    done = true;\n"  // it's an endgroup tag
         "  }\n"
         "  break;\n"
@@ -1070,8 +1061,7 @@ GenerateParsingConstructor(io::Printer* printer) {
     } else {
       printer->Print(
         "default: {\n"
-        "  if (!parseUnknownField(input, unknownFields,\n"
-        "                         extensionRegistry, tag)) {\n"
+        "  if (!parseUnknownField(tag, input)) {\n"
         "    done = true;\n"  // it's an endgroup tag
         "  }\n"
         "  break;\n"
@@ -1146,16 +1136,8 @@ GenerateParsingConstructor(io::Printer* printer) {
     field_generators_.get(field).GenerateParsingDoneCode(printer);
   }
 
-  if (PreserveUnknownFields(descriptor_)) {
-    // Make unknown fields immutable.
-    printer->Print("this.unknownFields = unknownFields.build();\n");
-  }
-
-  if (descriptor_->extension_range_count() > 0) {
-    // Make extensions immutable.
-    printer->Print(
-        "makeExtensionsImmutable(extensions);\n");
-  }
+  printer->Print(
+      "doneParsing();\n");
 
   printer->Outdent();
   printer->Outdent();
diff --git a/src/google/protobuf/compiler/parser.cc b/src/google/protobuf/compiler/parser.cc
index 4d018425..a389a4fc 100644
--- a/src/google/protobuf/compiler/parser.cc
+++ b/src/google/protobuf/compiler/parser.cc
@@ -993,6 +993,9 @@ bool Parser::ParseFieldOptions(FieldDescriptorProto* field,
       // We intentionally pass field_location rather than location here, since
       // the default value is not actually an option.
       DO(ParseDefaultAssignment(field, field_location, containing_file));
+    } else if (LookingAt("json_name")) {
+      // Like default value, this "json_name" is not an actual option.
+      DO(ParseJsonName(field, field_location, containing_file));
     } else {
       DO(ParseOption(field->mutable_options(), location,
                      containing_file, OPTION_ASSIGNMENT));
@@ -1140,6 +1143,28 @@ bool Parser::ParseDefaultAssignment(
   return true;
 }
 
+bool Parser::ParseJsonName(
+    FieldDescriptorProto* field,
+    const LocationRecorder& field_location,
+    const FileDescriptorProto* containing_file) {
+  if (field->has_json_name()) {
+    AddError("Already set option \"json_name\".");
+    field->clear_json_name();
+  }
+
+  DO(Consume("json_name"));
+  DO(Consume("="));
+
+  LocationRecorder location(field_location,
+                            FieldDescriptorProto::kJsonNameFieldNumber);
+  location.RecordLegacyLocation(
+      field, DescriptorPool::ErrorCollector::OPTION_VALUE);
+  DO(ConsumeString(field->mutable_json_name(),
+                   "Expected string for JSON name."));
+  return true;
+}
+
+
 bool Parser::ParseOptionNamePart(UninterpretedOption* uninterpreted_option,
                                  const LocationRecorder& part_location,
                                  const FileDescriptorProto* containing_file) {
diff --git a/src/google/protobuf/compiler/parser.h b/src/google/protobuf/compiler/parser.h
index 007b001c..3ba1e170 100644
--- a/src/google/protobuf/compiler/parser.h
+++ b/src/google/protobuf/compiler/parser.h
@@ -439,6 +439,10 @@ class LIBPROTOBUF_EXPORT Parser {
                               const LocationRecorder& field_location,
                               const FileDescriptorProto* containing_file);
 
+  bool ParseJsonName(FieldDescriptorProto* field,
+                     const LocationRecorder& field_location,
+                     const FileDescriptorProto* containing_file);
+
   enum OptionStyle {
     OPTION_ASSIGNMENT,  // just "name = value"
     OPTION_STATEMENT    // "option name = value;"
diff --git a/src/google/protobuf/compiler/parser_unittest.cc b/src/google/protobuf/compiler/parser_unittest.cc
index cc6f1efb..0d729e0b 100644
--- a/src/google/protobuf/compiler/parser_unittest.cc
+++ b/src/google/protobuf/compiler/parser_unittest.cc
@@ -452,6 +452,20 @@ TEST_F(ParseMessageTest, FieldDefaults) {
 #undef ETC
 }
 
+TEST_F(ParseMessageTest, FieldJsonName) {
+  ExpectParsesTo(
+    "message TestMessage {\n"
+    "  optional string foo = 1 [json_name = \"@type\"];\n"
+    "}\n",
+    "message_type {"
+    "  name: \"TestMessage\""
+    "  field {\n"
+    "    name: \"foo\" label: LABEL_OPTIONAL type: TYPE_STRING number: 1"
+    "    json_name: \"@type\"\n"
+    "  }\n"
+    "}\n");
+}
+
 TEST_F(ParseMessageTest, FieldOptions) {
   ExpectParsesTo(
     "message TestMessage {\n"
@@ -1126,6 +1140,22 @@ TEST_F(ParseErrorTest, DefaultValueTooLarge) {
     "6:36: Integer out of range.\n");
 }
 
+TEST_F(ParseErrorTest, JsonNameNotString) {
+  ExpectHasErrors(
+    "message TestMessage {\n"
+    "  optional string foo = 1 [json_name=1];\n"
+    "}\n",
+    "1:37: Expected string for JSON name.\n");
+}
+
+TEST_F(ParseErrorTest, DuplicateJsonName) {
+  ExpectHasErrors(
+    "message TestMessage {\n"
+    "  optional uint32 foo = 1 [json_name=\"a\",json_name=\"b\"];\n"
+    "}\n",
+    "1:41: Already set option \"json_name\".\n");
+}
+
 TEST_F(ParseErrorTest, EnumValueOutOfRange) {
   ExpectHasErrors(
     "enum TestEnum {\n"
diff --git a/src/google/protobuf/compiler/python/python_generator.cc b/src/google/protobuf/compiler/python/python_generator.cc
index e81af700..4d500f90 100644
--- a/src/google/protobuf/compiler/python/python_generator.cc
+++ b/src/google/protobuf/compiler/python/python_generator.cc
@@ -28,6 +28,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+//#PY25 compatible generated code for GAE.
 // Copyright 2007 Google Inc. All Rights Reserved.
 // Author: robinson@google.com (Will Robinson)
 //
@@ -166,6 +167,7 @@ void PrintTopBoilerplate(
   printer->Print(
       "# Generated by the protocol buffer compiler.  DO NOT EDIT!\n"
       "# source: $filename$\n"
+      "\nimport sys\n_b=sys.version_info[0]<3 and (lambda x:x) or (lambda x:x.encode('latin1'))"  //##PY25
       "\n",
       "filename", file->name());
   if (HasTopLevelEnums(file)) {
@@ -257,9 +259,12 @@ string StringifyDefaultValue(const FieldDescriptor& field) {
     case FieldDescriptor::CPPTYPE_ENUM:
       return SimpleItoa(field.default_value_enum()->number());
     case FieldDescriptor::CPPTYPE_STRING:
-      return "b\"" + CEscape(field.default_value_string()) +
-             (field.type() != FieldDescriptor::TYPE_STRING ? "\"" :
-               "\".decode('utf-8')");
+//##!PY25      return "b\"" + CEscape(field.default_value_string()) +
+//##!PY25             (field.type() != FieldDescriptor::TYPE_STRING ? "\"" :
+//##!PY25               "\".decode('utf-8')");
+      return "_b(\"" + CEscape(field.default_value_string()) +  //##PY25
+             (field.type() != FieldDescriptor::TYPE_STRING ? "\")" :  //##PY25
+               "\").decode('utf-8')");  //##PY25
     case FieldDescriptor::CPPTYPE_MESSAGE:
       return "None";
   }
@@ -385,7 +390,8 @@ void Generator::PrintFileDescriptor() const {
   printer_->Print(m, file_descriptor_template);
   printer_->Indent();
   printer_->Print(
-      "serialized_pb=b'$value$'\n",
+//##!PY25      "serialized_pb=b'$value$'\n",
+      "serialized_pb=_b('$value$')\n",  //##PY25
       "value", strings::CHexEscape(file_descriptor_serialized_));
   if (file_->dependency_count() != 0) {
     printer_->Print(",\ndependencies=[");
@@ -1029,8 +1035,10 @@ string Generator::OptionsValue(
     return "None";
   } else {
     string full_class_name = "descriptor_pb2." + class_name;
-    return "_descriptor._ParseOptions(" + full_class_name + "(), b'"
-        + CEscape(serialized_options)+ "')";
+//##!PY25    return "_descriptor._ParseOptions(" + full_class_name + "(), b'"
+//##!PY25        + CEscape(serialized_options)+ "')";
+    return "_descriptor._ParseOptions(" + full_class_name + "(), _b('"  //##PY25
+        + CEscape(serialized_options)+ "'))";  //##PY25
   }
 }
 
diff --git a/src/google/protobuf/descriptor.cc b/src/google/protobuf/descriptor.cc
index 5256b83c..b40fe95a 100644
--- a/src/google/protobuf/descriptor.cc
+++ b/src/google/protobuf/descriptor.cc
@@ -34,6 +34,10 @@
 
 #include <google/protobuf/stubs/hash.h>
 #include <map>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <set>
 #include <string>
 #include <vector>
@@ -1726,6 +1730,20 @@ void FileDescriptor::CopyTo(FileDescriptorProto* proto) const {
   }
 }
 
+void FileDescriptor::CopyJsonNameTo(FileDescriptorProto* proto) const {
+  if (message_type_count() != proto->message_type_size() ||
+      extension_count() != proto->extension_size()) {
+    GOOGLE_LOG(ERROR) << "Cannot copy json_name to a proto of a different size.";
+    return;
+  }
+  for (int i = 0; i < message_type_count(); i++) {
+    message_type(i)->CopyJsonNameTo(proto->mutable_message_type(i));
+  }
+  for (int i = 0; i < extension_count(); i++) {
+    extension(i)->CopyJsonNameTo(proto->mutable_extension(i));
+  }
+}
+
 void FileDescriptor::CopySourceCodeInfoTo(FileDescriptorProto* proto) const {
   if (source_code_info_ &&
       source_code_info_ != &SourceCodeInfo::default_instance()) {
@@ -1770,9 +1788,30 @@ void Descriptor::CopyTo(DescriptorProto* proto) const {
   }
 }
 
+void Descriptor::CopyJsonNameTo(DescriptorProto* proto) const {
+  if (field_count() != proto->field_size() ||
+      nested_type_count() != proto->nested_type_size() ||
+      extension_count() != proto->extension_size()) {
+    GOOGLE_LOG(ERROR) << "Cannot copy json_name to a proto of a different size.";
+    return;
+  }
+  for (int i = 0; i < field_count(); i++) {
+    field(i)->CopyJsonNameTo(proto->mutable_field(i));
+  }
+  for (int i = 0; i < nested_type_count(); i++) {
+    nested_type(i)->CopyJsonNameTo(proto->mutable_nested_type(i));
+  }
+  for (int i = 0; i < extension_count(); i++) {
+    extension(i)->CopyJsonNameTo(proto->mutable_extension(i));
+  }
+}
+
 void FieldDescriptor::CopyTo(FieldDescriptorProto* proto) const {
   proto->set_name(name());
   proto->set_number(number());
+  if (has_json_name_) {
+    proto->set_json_name(json_name());
+  }
 
   // Some compilers do not allow static_cast directly between two enum types,
   // so we must cast to int first.
@@ -1819,6 +1858,10 @@ void FieldDescriptor::CopyTo(FieldDescriptorProto* proto) const {
   }
 }
 
+void FieldDescriptor::CopyJsonNameTo(FieldDescriptorProto* proto) const {
+  proto->set_json_name(json_name());
+}
+
 void OneofDescriptor::CopyTo(OneofDescriptorProto* proto) const {
   proto->set_name(name());
 }
@@ -4136,6 +4179,14 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
       tables_->AllocateString(ToCamelCase(proto.name(),
                                           /* lower_first = */ true));
 
+  if (proto.has_json_name()) {
+    result->has_json_name_ = true;
+    result->json_name_ = tables_->AllocateString(proto.json_name());
+  } else {
+    result->has_json_name_ = false;
+    result->json_name_ = result->camelcase_name_;
+  }
+
   // Some compilers do not allow static_cast directly between two enum types,
   // so we must cast to int first.
   result->type_  = static_cast<FieldDescriptor::Type>(
@@ -5040,6 +5091,20 @@ void DescriptorBuilder::ValidateProto3(
   }
 }
 
+static string ToLowercaseWithoutUnderscores(const string& name) {
+  string result;
+  for (int i = 0; i < name.size(); ++i) {
+    if (name[i] != '_') {
+      if (name[i] >= 'A' && name[i] <= 'Z') {
+        result.push_back(name[i] - 'A' + 'a');
+      } else {
+        result.push_back(name[i]);
+      }
+    }
+  }
+  return result;
+}
+
 void DescriptorBuilder::ValidateProto3Message(
     Descriptor* message, const DescriptorProto& proto) {
   for (int i = 0; i < message->nested_type_count(); ++i) {
@@ -5067,6 +5132,25 @@ void DescriptorBuilder::ValidateProto3Message(
              DescriptorPool::ErrorCollector::OTHER,
              "MessageSet is not supported in proto3.");
   }
+
+  // In proto3, we reject field names if they conflict in camelCase.
+  // Note that we currently enforce a stricter rule: Field names must be
+  // unique after being converted to lowercase with underscores removed.
+  map<string, const FieldDescriptor*> name_to_field;
+  for (int i = 0; i < message->field_count(); ++i) {
+    string lowercase_name = ToLowercaseWithoutUnderscores(
+        message->field(i)->name());
+    if (name_to_field.find(lowercase_name) != name_to_field.end()) {
+      AddError(message->full_name(), proto,
+               DescriptorPool::ErrorCollector::OTHER,
+               "The JSON camcel-case name of field \"" +
+               message->field(i)->name() + "\" conflicts with field \"" +
+               name_to_field[lowercase_name]->name() + "\". This is not " +
+               "allowed in proto3.");
+    } else {
+      name_to_field[lowercase_name] = message->field(i);
+    }
+  }
 }
 
 void DescriptorBuilder::ValidateProto3Field(
@@ -5602,7 +5686,7 @@ bool DescriptorBuilder::OptionInterpreter::InterpretSingleOption(
 
   // First set the value on the UnknownFieldSet corresponding to the
   // innermost message.
-  scoped_ptr<UnknownFieldSet> unknown_fields(new UnknownFieldSet());
+  google::protobuf::scoped_ptr<UnknownFieldSet> unknown_fields(new UnknownFieldSet());
   if (!SetOptionValue(field, unknown_fields.get())) {
     return false;  // SetOptionValue() already added the error.
   }
@@ -5612,7 +5696,8 @@ bool DescriptorBuilder::OptionInterpreter::InterpretSingleOption(
   for (vector<const FieldDescriptor*>::reverse_iterator iter =
            intermediate_fields.rbegin();
        iter != intermediate_fields.rend(); ++iter) {
-    scoped_ptr<UnknownFieldSet> parent_unknown_fields(new UnknownFieldSet());
+    google::protobuf::scoped_ptr<UnknownFieldSet> parent_unknown_fields(
+        new UnknownFieldSet());
     switch ((*iter)->type()) {
       case FieldDescriptor::TYPE_MESSAGE: {
         io::StringOutputStream outstr(
@@ -5998,7 +6083,7 @@ bool DescriptorBuilder::OptionInterpreter::SetAggregateOption(
   }
 
   const Descriptor* type = option_field->message_type();
-  scoped_ptr<Message> dynamic(dynamic_factory_.GetPrototype(type)->New());
+  google::protobuf::scoped_ptr<Message> dynamic(dynamic_factory_.GetPrototype(type)->New());
   GOOGLE_CHECK(dynamic.get() != NULL)
       << "Could not create an instance of " << option_field->DebugString();
 
diff --git a/src/google/protobuf/descriptor.h b/src/google/protobuf/descriptor.h
index 2ab316a5..e7e8c6af 100644
--- a/src/google/protobuf/descriptor.h
+++ b/src/google/protobuf/descriptor.h
@@ -54,6 +54,10 @@
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_H__
 #define GOOGLE_PROTOBUF_DESCRIPTOR_H__
 
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <set>
 #include <string>
 #include <vector>
@@ -111,8 +115,17 @@ class UnknownField;
 
 // Defined in generated_message_reflection.h.
 namespace internal {
-  class GeneratedMessageReflection;
-}
+class GeneratedMessageReflection;
+}  // namespace internal
+
+// Defined in command_line_interface.cc
+namespace compiler {
+class CommandLineInterface;
+}  // namespace compiler
+
+namespace descriptor_unittest {
+class DescriptorTest;
+}  // namespace descriptor_unittest
 
 // NB, all indices are zero-based.
 struct SourceLocation {
@@ -343,6 +356,12 @@ class LIBPROTOBUF_EXPORT Descriptor {
  private:
   typedef MessageOptions OptionsType;
 
+  // Allows tests to test CopyTo(proto, true).
+  friend class ::google::protobuf::descriptor_unittest::DescriptorTest;
+
+  // Fill the json_name field of FieldDescriptorProto.
+  void CopyJsonNameTo(DescriptorProto* proto) const;
+
   // Internal version of DebugString; controls the level of indenting for
   // correct depth. Takes |options| to control debug-string options, and
   // |include_opening_clause| to indicate whether the "message ... " part of the
@@ -484,6 +503,7 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
 
   const string& name() const;        // Name of this field within the message.
   const string& full_name() const;   // Fully-qualified name of the field.
+  const string& json_name() const;   // JSON name of this field.
   const FileDescriptor* file() const;// File in which this field was defined.
   bool is_extension() const;         // Is this an extension field?
   int number() const;                // Declared tag number.
@@ -624,6 +644,9 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
  private:
   typedef FieldOptions OptionsType;
 
+  // Fill the json_name field of FieldDescriptorProto.
+  void CopyJsonNameTo(FieldDescriptorProto* proto) const;
+
   // See Descriptor::DebugString().
   enum PrintLabelFlag { PRINT_LABEL, OMIT_LABEL };
   void DebugString(int depth, PrintLabelFlag print_label_flag,
@@ -645,6 +668,12 @@ class LIBPROTOBUF_EXPORT FieldDescriptor {
   const string* full_name_;
   const string* lowercase_name_;
   const string* camelcase_name_;
+  // Whether the user has specified the json_name field option in the .proto
+  // file.
+  bool has_json_name_;
+  // If has_json_name_ is true, it's the value specified by the user.
+  // Otherwise, it has the same value as lowercase_name_.
+  const string* json_name_;
   const FileDescriptor* file_;
   int number_;
   Type type_;
@@ -1202,6 +1231,9 @@ class LIBPROTOBUF_EXPORT FileDescriptor {
   // Write the source code information of this FileDescriptor into the given
   // FileDescriptorProto.  See CopyTo() above.
   void CopySourceCodeInfoTo(FileDescriptorProto* proto) const;
+  // Fill the json_name field of FieldDescriptorProto for all fields. Can only
+  // be called after CopyTo().
+  void CopyJsonNameTo(FileDescriptorProto* proto) const;
 
   // See Descriptor::DebugString().
   string DebugString() const;
@@ -1559,7 +1591,7 @@ class LIBPROTOBUF_EXPORT DescriptorPool {
   // This class contains a lot of hash maps with complicated types that
   // we'd like to keep out of the header.
   class Tables;
-  scoped_ptr<Tables> tables_;
+  google::protobuf::scoped_ptr<Tables> tables_;
 
   bool enforce_dependencies_;
   bool allow_unknown_;
@@ -1618,6 +1650,7 @@ PROTOBUF_DEFINE_ACCESSOR(Descriptor, is_placeholder, bool)
 
 PROTOBUF_DEFINE_STRING_ACCESSOR(FieldDescriptor, name)
 PROTOBUF_DEFINE_STRING_ACCESSOR(FieldDescriptor, full_name)
+PROTOBUF_DEFINE_STRING_ACCESSOR(FieldDescriptor, json_name)
 PROTOBUF_DEFINE_STRING_ACCESSOR(FieldDescriptor, lowercase_name)
 PROTOBUF_DEFINE_STRING_ACCESSOR(FieldDescriptor, camelcase_name)
 PROTOBUF_DEFINE_ACCESSOR(FieldDescriptor, file, const FileDescriptor*)
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index fe23c0ab..921d2cd0 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -200,7 +200,7 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
       GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(DescriptorProto_ReservedRange, _internal_metadata_),
       -1);
   FieldDescriptorProto_descriptor_ = file->message_type(3);
-  static const int FieldDescriptorProto_offsets_[9] = {
+  static const int FieldDescriptorProto_offsets_[10] = {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, name_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, number_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, label_),
@@ -209,6 +209,7 @@ void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto() {
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, extendee_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, default_value_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, oneof_index_),
+    GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, json_name_),
     GOOGLE_PROTOBUF_GENERATED_MESSAGE_FIELD_OFFSET(FieldDescriptorProto, options_),
   };
   FieldDescriptorProto_reflection_ =
@@ -663,101 +664,101 @@ void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() {
     "tobuf.DescriptorProto.ReservedRange\022\025\n\rr"
     "eserved_name\030\n \003(\t\032,\n\016ExtensionRange\022\r\n\005"
     "start\030\001 \001(\005\022\013\n\003end\030\002 \001(\005\032+\n\rReservedRang"
-    "e\022\r\n\005start\030\001 \001(\005\022\013\n\003end\030\002 \001(\005\"\251\005\n\024FieldD"
+    "e\022\r\n\005start\030\001 \001(\005\022\013\n\003end\030\002 \001(\005\"\274\005\n\024FieldD"
     "escriptorProto\022\014\n\004name\030\001 \001(\t\022\016\n\006number\030\003"
     " \001(\005\022:\n\005label\030\004 \001(\0162+.google.protobuf.Fi"
     "eldDescriptorProto.Label\0228\n\004type\030\005 \001(\0162*"
     ".google.protobuf.FieldDescriptorProto.Ty"
     "pe\022\021\n\ttype_name\030\006 \001(\t\022\020\n\010extendee\030\002 \001(\t\022"
     "\025\n\rdefault_value\030\007 \001(\t\022\023\n\013oneof_index\030\t "
-    "\001(\005\022.\n\007options\030\010 \001(\0132\035.google.protobuf.F"
-    "ieldOptions\"\266\002\n\004Type\022\017\n\013TYPE_DOUBLE\020\001\022\016\n"
-    "\nTYPE_FLOAT\020\002\022\016\n\nTYPE_INT64\020\003\022\017\n\013TYPE_UI"
-    "NT64\020\004\022\016\n\nTYPE_INT32\020\005\022\020\n\014TYPE_FIXED64\020\006"
-    "\022\020\n\014TYPE_FIXED32\020\007\022\r\n\tTYPE_BOOL\020\010\022\017\n\013TYP"
-    "E_STRING\020\t\022\016\n\nTYPE_GROUP\020\n\022\020\n\014TYPE_MESSA"
-    "GE\020\013\022\016\n\nTYPE_BYTES\020\014\022\017\n\013TYPE_UINT32\020\r\022\r\n"
-    "\tTYPE_ENUM\020\016\022\021\n\rTYPE_SFIXED32\020\017\022\021\n\rTYPE_"
-    "SFIXED64\020\020\022\017\n\013TYPE_SINT32\020\021\022\017\n\013TYPE_SINT"
-    "64\020\022\"C\n\005Label\022\022\n\016LABEL_OPTIONAL\020\001\022\022\n\016LAB"
-    "EL_REQUIRED\020\002\022\022\n\016LABEL_REPEATED\020\003\"$\n\024One"
-    "ofDescriptorProto\022\014\n\004name\030\001 \001(\t\"\214\001\n\023Enum"
-    "DescriptorProto\022\014\n\004name\030\001 \001(\t\0228\n\005value\030\002"
-    " \003(\0132).google.protobuf.EnumValueDescript"
-    "orProto\022-\n\007options\030\003 \001(\0132\034.google.protob"
-    "uf.EnumOptions\"l\n\030EnumValueDescriptorPro"
-    "to\022\014\n\004name\030\001 \001(\t\022\016\n\006number\030\002 \001(\005\0222\n\007opti"
-    "ons\030\003 \001(\0132!.google.protobuf.EnumValueOpt"
-    "ions\"\220\001\n\026ServiceDescriptorProto\022\014\n\004name\030"
-    "\001 \001(\t\0226\n\006method\030\002 \003(\0132&.google.protobuf."
-    "MethodDescriptorProto\0220\n\007options\030\003 \001(\0132\037"
-    ".google.protobuf.ServiceOptions\"\301\001\n\025Meth"
-    "odDescriptorProto\022\014\n\004name\030\001 \001(\t\022\022\n\ninput"
-    "_type\030\002 \001(\t\022\023\n\013output_type\030\003 \001(\t\022/\n\007opti"
-    "ons\030\004 \001(\0132\036.google.protobuf.MethodOption"
-    "s\022\037\n\020client_streaming\030\005 \001(\010:\005false\022\037\n\020se"
-    "rver_streaming\030\006 \001(\010:\005false\"\252\005\n\013FileOpti"
-    "ons\022\024\n\014java_package\030\001 \001(\t\022\034\n\024java_outer_"
-    "classname\030\010 \001(\t\022\"\n\023java_multiple_files\030\n"
-    " \001(\010:\005false\022,\n\035java_generate_equals_and_"
-    "hash\030\024 \001(\010:\005false\022%\n\026java_string_check_u"
-    "tf8\030\033 \001(\010:\005false\022F\n\014optimize_for\030\t \001(\0162)"
-    ".google.protobuf.FileOptions.OptimizeMod"
-    "e:\005SPEED\022\022\n\ngo_package\030\013 \001(\t\022\"\n\023cc_gener"
-    "ic_services\030\020 \001(\010:\005false\022$\n\025java_generic"
-    "_services\030\021 \001(\010:\005false\022\"\n\023py_generic_ser"
-    "vices\030\022 \001(\010:\005false\022\031\n\ndeprecated\030\027 \001(\010:\005"
-    "false\022\037\n\020cc_enable_arenas\030\037 \001(\010:\005false\022\031"
-    "\n\021objc_class_prefix\030$ \001(\t\022\030\n\020csharp_name"
-    "space\030% \001(\t\022\'\n\037javanano_use_deprecated_p"
-    "ackage\030& \001(\010\022C\n\024uninterpreted_option\030\347\007 "
-    "\003(\0132$.google.protobuf.UninterpretedOptio"
-    "n\":\n\014OptimizeMode\022\t\n\005SPEED\020\001\022\r\n\tCODE_SIZ"
-    "E\020\002\022\020\n\014LITE_RUNTIME\020\003*\t\010\350\007\020\200\200\200\200\002\"\346\001\n\016Mes"
-    "sageOptions\022&\n\027message_set_wire_format\030\001"
-    " \001(\010:\005false\022.\n\037no_standard_descriptor_ac"
-    "cessor\030\002 \001(\010:\005false\022\031\n\ndeprecated\030\003 \001(\010:"
-    "\005false\022\021\n\tmap_entry\030\007 \001(\010\022C\n\024uninterpret"
-    "ed_option\030\347\007 \003(\0132$.google.protobuf.Unint"
-    "erpretedOption*\t\010\350\007\020\200\200\200\200\002\"\230\003\n\014FieldOptio"
-    "ns\022:\n\005ctype\030\001 \001(\0162#.google.protobuf.Fiel"
-    "dOptions.CType:\006STRING\022\016\n\006packed\030\002 \001(\010\022\?"
-    "\n\006jstype\030\006 \001(\0162$.google.protobuf.FieldOp"
-    "tions.JSType:\tJS_NORMAL\022\023\n\004lazy\030\005 \001(\010:\005f"
-    "alse\022\031\n\ndeprecated\030\003 \001(\010:\005false\022\023\n\004weak\030"
-    "\n \001(\010:\005false\022C\n\024uninterpreted_option\030\347\007 "
-    "\003(\0132$.google.protobuf.UninterpretedOptio"
-    "n\"/\n\005CType\022\n\n\006STRING\020\000\022\010\n\004CORD\020\001\022\020\n\014STRI"
-    "NG_PIECE\020\002\"5\n\006JSType\022\r\n\tJS_NORMAL\020\000\022\r\n\tJ"
-    "S_STRING\020\001\022\r\n\tJS_NUMBER\020\002*\t\010\350\007\020\200\200\200\200\002\"\215\001\n"
-    "\013EnumOptions\022\023\n\013allow_alias\030\002 \001(\010\022\031\n\ndep"
-    "recated\030\003 \001(\010:\005false\022C\n\024uninterpreted_op"
-    "tion\030\347\007 \003(\0132$.google.protobuf.Uninterpre"
-    "tedOption*\t\010\350\007\020\200\200\200\200\002\"}\n\020EnumValueOptions"
-    "\022\031\n\ndeprecated\030\001 \001(\010:\005false\022C\n\024uninterpr"
-    "eted_option\030\347\007 \003(\0132$.google.protobuf.Uni"
-    "nterpretedOption*\t\010\350\007\020\200\200\200\200\002\"{\n\016ServiceOp"
-    "tions\022\031\n\ndeprecated\030! \001(\010:\005false\022C\n\024unin"
-    "terpreted_option\030\347\007 \003(\0132$.google.protobu"
-    "f.UninterpretedOption*\t\010\350\007\020\200\200\200\200\002\"z\n\rMeth"
-    "odOptions\022\031\n\ndeprecated\030! \001(\010:\005false\022C\n\024"
-    "uninterpreted_option\030\347\007 \003(\0132$.google.pro"
-    "tobuf.UninterpretedOption*\t\010\350\007\020\200\200\200\200\002\"\236\002\n"
-    "\023UninterpretedOption\022;\n\004name\030\002 \003(\0132-.goo"
-    "gle.protobuf.UninterpretedOption.NamePar"
-    "t\022\030\n\020identifier_value\030\003 \001(\t\022\032\n\022positive_"
-    "int_value\030\004 \001(\004\022\032\n\022negative_int_value\030\005 "
-    "\001(\003\022\024\n\014double_value\030\006 \001(\001\022\024\n\014string_valu"
-    "e\030\007 \001(\014\022\027\n\017aggregate_value\030\010 \001(\t\0323\n\010Name"
-    "Part\022\021\n\tname_part\030\001 \002(\t\022\024\n\014is_extension\030"
-    "\002 \002(\010\"\325\001\n\016SourceCodeInfo\022:\n\010location\030\001 \003"
-    "(\0132(.google.protobuf.SourceCodeInfo.Loca"
-    "tion\032\206\001\n\010Location\022\020\n\004path\030\001 \003(\005B\002\020\001\022\020\n\004s"
-    "pan\030\002 \003(\005B\002\020\001\022\030\n\020leading_comments\030\003 \001(\t\022"
-    "\031\n\021trailing_comments\030\004 \001(\t\022!\n\031leading_de"
-    "tached_comments\030\006 \003(\tB;\n\023com.google.prot"
-    "obufB\020DescriptorProtosH\001Z\ndescriptor\242\002\003G"
-    "PB", 4962);
+    "\001(\005\022\021\n\tjson_name\030\n \001(\t\022.\n\007options\030\010 \001(\0132"
+    "\035.google.protobuf.FieldOptions\"\266\002\n\004Type\022"
+    "\017\n\013TYPE_DOUBLE\020\001\022\016\n\nTYPE_FLOAT\020\002\022\016\n\nTYPE"
+    "_INT64\020\003\022\017\n\013TYPE_UINT64\020\004\022\016\n\nTYPE_INT32\020"
+    "\005\022\020\n\014TYPE_FIXED64\020\006\022\020\n\014TYPE_FIXED32\020\007\022\r\n"
+    "\tTYPE_BOOL\020\010\022\017\n\013TYPE_STRING\020\t\022\016\n\nTYPE_GR"
+    "OUP\020\n\022\020\n\014TYPE_MESSAGE\020\013\022\016\n\nTYPE_BYTES\020\014\022"
+    "\017\n\013TYPE_UINT32\020\r\022\r\n\tTYPE_ENUM\020\016\022\021\n\rTYPE_"
+    "SFIXED32\020\017\022\021\n\rTYPE_SFIXED64\020\020\022\017\n\013TYPE_SI"
+    "NT32\020\021\022\017\n\013TYPE_SINT64\020\022\"C\n\005Label\022\022\n\016LABE"
+    "L_OPTIONAL\020\001\022\022\n\016LABEL_REQUIRED\020\002\022\022\n\016LABE"
+    "L_REPEATED\020\003\"$\n\024OneofDescriptorProto\022\014\n\004"
+    "name\030\001 \001(\t\"\214\001\n\023EnumDescriptorProto\022\014\n\004na"
+    "me\030\001 \001(\t\0228\n\005value\030\002 \003(\0132).google.protobu"
+    "f.EnumValueDescriptorProto\022-\n\007options\030\003 "
+    "\001(\0132\034.google.protobuf.EnumOptions\"l\n\030Enu"
+    "mValueDescriptorProto\022\014\n\004name\030\001 \001(\t\022\016\n\006n"
+    "umber\030\002 \001(\005\0222\n\007options\030\003 \001(\0132!.google.pr"
+    "otobuf.EnumValueOptions\"\220\001\n\026ServiceDescr"
+    "iptorProto\022\014\n\004name\030\001 \001(\t\0226\n\006method\030\002 \003(\013"
+    "2&.google.protobuf.MethodDescriptorProto"
+    "\0220\n\007options\030\003 \001(\0132\037.google.protobuf.Serv"
+    "iceOptions\"\301\001\n\025MethodDescriptorProto\022\014\n\004"
+    "name\030\001 \001(\t\022\022\n\ninput_type\030\002 \001(\t\022\023\n\013output"
+    "_type\030\003 \001(\t\022/\n\007options\030\004 \001(\0132\036.google.pr"
+    "otobuf.MethodOptions\022\037\n\020client_streaming"
+    "\030\005 \001(\010:\005false\022\037\n\020server_streaming\030\006 \001(\010:"
+    "\005false\"\252\005\n\013FileOptions\022\024\n\014java_package\030\001"
+    " \001(\t\022\034\n\024java_outer_classname\030\010 \001(\t\022\"\n\023ja"
+    "va_multiple_files\030\n \001(\010:\005false\022,\n\035java_g"
+    "enerate_equals_and_hash\030\024 \001(\010:\005false\022%\n\026"
+    "java_string_check_utf8\030\033 \001(\010:\005false\022F\n\014o"
+    "ptimize_for\030\t \001(\0162).google.protobuf.File"
+    "Options.OptimizeMode:\005SPEED\022\022\n\ngo_packag"
+    "e\030\013 \001(\t\022\"\n\023cc_generic_services\030\020 \001(\010:\005fa"
+    "lse\022$\n\025java_generic_services\030\021 \001(\010:\005fals"
+    "e\022\"\n\023py_generic_services\030\022 \001(\010:\005false\022\031\n"
+    "\ndeprecated\030\027 \001(\010:\005false\022\037\n\020cc_enable_ar"
+    "enas\030\037 \001(\010:\005false\022\031\n\021objc_class_prefix\030$"
+    " \001(\t\022\030\n\020csharp_namespace\030% \001(\t\022\'\n\037javana"
+    "no_use_deprecated_package\030& \001(\010\022C\n\024unint"
+    "erpreted_option\030\347\007 \003(\0132$.google.protobuf"
+    ".UninterpretedOption\":\n\014OptimizeMode\022\t\n\005"
+    "SPEED\020\001\022\r\n\tCODE_SIZE\020\002\022\020\n\014LITE_RUNTIME\020\003"
+    "*\t\010\350\007\020\200\200\200\200\002\"\346\001\n\016MessageOptions\022&\n\027messag"
+    "e_set_wire_format\030\001 \001(\010:\005false\022.\n\037no_sta"
+    "ndard_descriptor_accessor\030\002 \001(\010:\005false\022\031"
+    "\n\ndeprecated\030\003 \001(\010:\005false\022\021\n\tmap_entry\030\007"
+    " \001(\010\022C\n\024uninterpreted_option\030\347\007 \003(\0132$.go"
+    "ogle.protobuf.UninterpretedOption*\t\010\350\007\020\200"
+    "\200\200\200\002\"\230\003\n\014FieldOptions\022:\n\005ctype\030\001 \001(\0162#.g"
+    "oogle.protobuf.FieldOptions.CType:\006STRIN"
+    "G\022\016\n\006packed\030\002 \001(\010\022\?\n\006jstype\030\006 \001(\0162$.goog"
+    "le.protobuf.FieldOptions.JSType:\tJS_NORM"
+    "AL\022\023\n\004lazy\030\005 \001(\010:\005false\022\031\n\ndeprecated\030\003 "
+    "\001(\010:\005false\022\023\n\004weak\030\n \001(\010:\005false\022C\n\024unint"
+    "erpreted_option\030\347\007 \003(\0132$.google.protobuf"
+    ".UninterpretedOption\"/\n\005CType\022\n\n\006STRING\020"
+    "\000\022\010\n\004CORD\020\001\022\020\n\014STRING_PIECE\020\002\"5\n\006JSType\022"
+    "\r\n\tJS_NORMAL\020\000\022\r\n\tJS_STRING\020\001\022\r\n\tJS_NUMB"
+    "ER\020\002*\t\010\350\007\020\200\200\200\200\002\"\215\001\n\013EnumOptions\022\023\n\013allow"
+    "_alias\030\002 \001(\010\022\031\n\ndeprecated\030\003 \001(\010:\005false\022"
+    "C\n\024uninterpreted_option\030\347\007 \003(\0132$.google."
+    "protobuf.UninterpretedOption*\t\010\350\007\020\200\200\200\200\002\""
+    "}\n\020EnumValueOptions\022\031\n\ndeprecated\030\001 \001(\010:"
+    "\005false\022C\n\024uninterpreted_option\030\347\007 \003(\0132$."
+    "google.protobuf.UninterpretedOption*\t\010\350\007"
+    "\020\200\200\200\200\002\"{\n\016ServiceOptions\022\031\n\ndeprecated\030!"
+    " \001(\010:\005false\022C\n\024uninterpreted_option\030\347\007 \003"
+    "(\0132$.google.protobuf.UninterpretedOption"
+    "*\t\010\350\007\020\200\200\200\200\002\"z\n\rMethodOptions\022\031\n\ndeprecat"
+    "ed\030! \001(\010:\005false\022C\n\024uninterpreted_option\030"
+    "\347\007 \003(\0132$.google.protobuf.UninterpretedOp"
+    "tion*\t\010\350\007\020\200\200\200\200\002\"\236\002\n\023UninterpretedOption\022"
+    ";\n\004name\030\002 \003(\0132-.google.protobuf.Uninterp"
+    "retedOption.NamePart\022\030\n\020identifier_value"
+    "\030\003 \001(\t\022\032\n\022positive_int_value\030\004 \001(\004\022\032\n\022ne"
+    "gative_int_value\030\005 \001(\003\022\024\n\014double_value\030\006"
+    " \001(\001\022\024\n\014string_value\030\007 \001(\014\022\027\n\017aggregate_"
+    "value\030\010 \001(\t\0323\n\010NamePart\022\021\n\tname_part\030\001 \002"
+    "(\t\022\024\n\014is_extension\030\002 \002(\010\"\325\001\n\016SourceCodeI"
+    "nfo\022:\n\010location\030\001 \003(\0132(.google.protobuf."
+    "SourceCodeInfo.Location\032\206\001\n\010Location\022\020\n\004"
+    "path\030\001 \003(\005B\002\020\001\022\020\n\004span\030\002 \003(\005B\002\020\001\022\030\n\020lead"
+    "ing_comments\030\003 \001(\t\022\031\n\021trailing_comments\030"
+    "\004 \001(\t\022!\n\031leading_detached_comments\030\006 \003(\t"
+    "B;\n\023com.google.protobufB\020DescriptorProto"
+    "sH\001Z\ndescriptor\242\002\003GPB", 4981);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/descriptor.proto", &protobuf_RegisterTypes);
   FileDescriptorSet::default_instance_ = new FileDescriptorSet();
@@ -4109,6 +4110,7 @@ const int FieldDescriptorProto::kTypeNameFieldNumber;
 const int FieldDescriptorProto::kExtendeeFieldNumber;
 const int FieldDescriptorProto::kDefaultValueFieldNumber;
 const int FieldDescriptorProto::kOneofIndexFieldNumber;
+const int FieldDescriptorProto::kJsonNameFieldNumber;
 const int FieldDescriptorProto::kOptionsFieldNumber;
 #endif  // !_MSC_VER
 
@@ -4141,6 +4143,7 @@ void FieldDescriptorProto::SharedCtor() {
   extendee_.UnsafeSetDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   default_value_.UnsafeSetDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   oneof_index_ = 0;
+  json_name_.UnsafeSetDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   options_ = NULL;
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
 }
@@ -4155,6 +4158,7 @@ void FieldDescriptorProto::SharedDtor() {
   type_name_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   extendee_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   default_value_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  json_name_.DestroyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
   if (this != default_instance_) {
     delete options_;
   }
@@ -4204,8 +4208,13 @@ void FieldDescriptorProto::Clear() {
     }
     oneof_index_ = 0;
   }
-  if (has_options()) {
-    if (options_ != NULL) options_->::google::protobuf::FieldOptions::Clear();
+  if (_has_bits_[8 / 32] & 768u) {
+    if (has_json_name()) {
+      json_name_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+    }
+    if (has_options()) {
+      if (options_ != NULL) options_->::google::protobuf::FieldOptions::Clear();
+    }
   }
   ::memset(_has_bits_, 0, sizeof(_has_bits_));
   if (_internal_metadata_.have_unknown_fields()) {
@@ -4369,6 +4378,23 @@ bool FieldDescriptorProto::MergePartialFromCodedStream(
         } else {
           goto handle_unusual;
         }
+        if (input->ExpectTag(82)) goto parse_json_name;
+        break;
+      }
+
+      // optional string json_name = 10;
+      case 10: {
+        if (tag == 82) {
+         parse_json_name:
+          DO_(::google::protobuf::internal::WireFormatLite::ReadString(
+                input, this->mutable_json_name()));
+          ::google::protobuf::internal::WireFormat::VerifyUTF8StringNamedField(
+            this->json_name().data(), this->json_name().length(),
+            ::google::protobuf::internal::WireFormat::PARSE,
+            "google.protobuf.FieldDescriptorProto.json_name");
+        } else {
+          goto handle_unusual;
+        }
         if (input->ExpectAtEnd()) goto success;
         break;
       }
@@ -4466,6 +4492,16 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     ::google::protobuf::internal::WireFormatLite::WriteInt32(9, this->oneof_index(), output);
   }
 
+  // optional string json_name = 10;
+  if (has_json_name()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8StringNamedField(
+      this->json_name().data(), this->json_name().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE,
+      "google.protobuf.FieldDescriptorProto.json_name");
+    ::google::protobuf::internal::WireFormatLite::WriteStringMaybeAliased(
+      10, this->json_name(), output);
+  }
+
   if (_internal_metadata_.have_unknown_fields()) {
     ::google::protobuf::internal::WireFormat::SerializeUnknownFields(
         unknown_fields(), output);
@@ -4549,6 +4585,17 @@ void FieldDescriptorProto::SerializeWithCachedSizes(
     target = ::google::protobuf::internal::WireFormatLite::WriteInt32ToArray(9, this->oneof_index(), target);
   }
 
+  // optional string json_name = 10;
+  if (has_json_name()) {
+    ::google::protobuf::internal::WireFormat::VerifyUTF8StringNamedField(
+      this->json_name().data(), this->json_name().length(),
+      ::google::protobuf::internal::WireFormat::SERIALIZE,
+      "google.protobuf.FieldDescriptorProto.json_name");
+    target =
+      ::google::protobuf::internal::WireFormatLite::WriteStringToArray(
+        10, this->json_name(), target);
+  }
+
   if (_internal_metadata_.have_unknown_fields()) {
     target = ::google::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(
         unknown_fields(), target);
@@ -4616,13 +4663,22 @@ int FieldDescriptorProto::ByteSize() const {
     }
 
   }
-  // optional .google.protobuf.FieldOptions options = 8;
-  if (has_options()) {
-    total_size += 1 +
-      ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
-        *this->options_);
-  }
+  if (_has_bits_[8 / 32] & 768u) {
+    // optional string json_name = 10;
+    if (has_json_name()) {
+      total_size += 1 +
+        ::google::protobuf::internal::WireFormatLite::StringSize(
+          this->json_name());
+    }
 
+    // optional .google.protobuf.FieldOptions options = 8;
+    if (has_options()) {
+      total_size += 1 +
+        ::google::protobuf::internal::WireFormatLite::MessageSizeNoVirtual(
+          *this->options_);
+    }
+
+  }
   if (_internal_metadata_.have_unknown_fields()) {
     total_size +=
       ::google::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(
@@ -4679,6 +4735,10 @@ void FieldDescriptorProto::MergeFrom(const FieldDescriptorProto& from) {
     }
   }
   if (from._has_bits_[8 / 32] & (0xffu << (8 % 32))) {
+    if (from.has_json_name()) {
+      set_has_json_name();
+      json_name_.AssignWithDefault(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), from.json_name_);
+    }
     if (from.has_options()) {
       mutable_options()->::google::protobuf::FieldOptions::MergeFrom(from.options());
     }
@@ -4721,6 +4781,7 @@ void FieldDescriptorProto::InternalSwap(FieldDescriptorProto* other) {
   extendee_.Swap(&other->extendee_);
   default_value_.Swap(&other->default_value_);
   std::swap(oneof_index_, other->oneof_index_);
+  json_name_.Swap(&other->json_name_);
   std::swap(options_, other->options_);
   std::swap(_has_bits_[0], other->_has_bits_[0]);
   _internal_metadata_.Swap(&other->_internal_metadata_);
@@ -5048,15 +5109,68 @@ void FieldDescriptorProto::clear_oneof_index() {
   // @@protoc_insertion_point(field_set:google.protobuf.FieldDescriptorProto.oneof_index)
 }
 
+// optional string json_name = 10;
+bool FieldDescriptorProto::has_json_name() const {
+  return (_has_bits_[0] & 0x00000100u) != 0;
+}
+void FieldDescriptorProto::set_has_json_name() {
+  _has_bits_[0] |= 0x00000100u;
+}
+void FieldDescriptorProto::clear_has_json_name() {
+  _has_bits_[0] &= ~0x00000100u;
+}
+void FieldDescriptorProto::clear_json_name() {
+  json_name_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  clear_has_json_name();
+}
+ const ::std::string& FieldDescriptorProto::json_name() const {
+  // @@protoc_insertion_point(field_get:google.protobuf.FieldDescriptorProto.json_name)
+  return json_name_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ void FieldDescriptorProto::set_json_name(const ::std::string& value) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  // @@protoc_insertion_point(field_set:google.protobuf.FieldDescriptorProto.json_name)
+}
+ void FieldDescriptorProto::set_json_name(const char* value) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  // @@protoc_insertion_point(field_set_char:google.protobuf.FieldDescriptorProto.json_name)
+}
+ void FieldDescriptorProto::set_json_name(const char* value, size_t size) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      ::std::string(reinterpret_cast<const char*>(value), size));
+  // @@protoc_insertion_point(field_set_pointer:google.protobuf.FieldDescriptorProto.json_name)
+}
+ ::std::string* FieldDescriptorProto::mutable_json_name() {
+  set_has_json_name();
+  // @@protoc_insertion_point(field_mutable:google.protobuf.FieldDescriptorProto.json_name)
+  return json_name_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ ::std::string* FieldDescriptorProto::release_json_name() {
+  clear_has_json_name();
+  return json_name_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+ void FieldDescriptorProto::set_allocated_json_name(::std::string* json_name) {
+  if (json_name != NULL) {
+    set_has_json_name();
+  } else {
+    clear_has_json_name();
+  }
+  json_name_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), json_name);
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.FieldDescriptorProto.json_name)
+}
+
 // optional .google.protobuf.FieldOptions options = 8;
 bool FieldDescriptorProto::has_options() const {
-  return (_has_bits_[0] & 0x00000100u) != 0;
+  return (_has_bits_[0] & 0x00000200u) != 0;
 }
 void FieldDescriptorProto::set_has_options() {
-  _has_bits_[0] |= 0x00000100u;
+  _has_bits_[0] |= 0x00000200u;
 }
 void FieldDescriptorProto::clear_has_options() {
-  _has_bits_[0] &= ~0x00000100u;
+  _has_bits_[0] &= ~0x00000200u;
 }
 void FieldDescriptorProto::clear_options() {
   if (options_ != NULL) options_->::google::protobuf::FieldOptions::Clear();
diff --git a/src/google/protobuf/descriptor.pb.h b/src/google/protobuf/descriptor.pb.h
index 931ff02d..60255162 100644
--- a/src/google/protobuf/descriptor.pb.h
+++ b/src/google/protobuf/descriptor.pb.h
@@ -1133,6 +1133,18 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   ::google::protobuf::int32 oneof_index() const;
   void set_oneof_index(::google::protobuf::int32 value);
 
+  // optional string json_name = 10;
+  bool has_json_name() const;
+  void clear_json_name();
+  static const int kJsonNameFieldNumber = 10;
+  const ::std::string& json_name() const;
+  void set_json_name(const ::std::string& value);
+  void set_json_name(const char* value);
+  void set_json_name(const char* value, size_t size);
+  ::std::string* mutable_json_name();
+  ::std::string* release_json_name();
+  void set_allocated_json_name(::std::string* json_name);
+
   // optional .google.protobuf.FieldOptions options = 8;
   bool has_options() const;
   void clear_options();
@@ -1160,6 +1172,8 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   inline void clear_has_default_value();
   inline void set_has_oneof_index();
   inline void clear_has_oneof_index();
+  inline void set_has_json_name();
+  inline void clear_has_json_name();
   inline void set_has_options();
   inline void clear_has_options();
 
@@ -1174,6 +1188,7 @@ class LIBPROTOBUF_EXPORT FieldDescriptorProto : public ::google::protobuf::Messa
   int type_;
   ::google::protobuf::int32 oneof_index_;
   ::google::protobuf::internal::ArenaStringPtr default_value_;
+  ::google::protobuf::internal::ArenaStringPtr json_name_;
   ::google::protobuf::FieldOptions* options_;
   friend void LIBPROTOBUF_EXPORT protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto();
   friend void protobuf_AssignDesc_google_2fprotobuf_2fdescriptor_2eproto();
@@ -4678,15 +4693,68 @@ inline void FieldDescriptorProto::set_oneof_index(::google::protobuf::int32 valu
   // @@protoc_insertion_point(field_set:google.protobuf.FieldDescriptorProto.oneof_index)
 }
 
+// optional string json_name = 10;
+inline bool FieldDescriptorProto::has_json_name() const {
+  return (_has_bits_[0] & 0x00000100u) != 0;
+}
+inline void FieldDescriptorProto::set_has_json_name() {
+  _has_bits_[0] |= 0x00000100u;
+}
+inline void FieldDescriptorProto::clear_has_json_name() {
+  _has_bits_[0] &= ~0x00000100u;
+}
+inline void FieldDescriptorProto::clear_json_name() {
+  json_name_.ClearToEmptyNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+  clear_has_json_name();
+}
+inline const ::std::string& FieldDescriptorProto::json_name() const {
+  // @@protoc_insertion_point(field_get:google.protobuf.FieldDescriptorProto.json_name)
+  return json_name_.GetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline void FieldDescriptorProto::set_json_name(const ::std::string& value) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), value);
+  // @@protoc_insertion_point(field_set:google.protobuf.FieldDescriptorProto.json_name)
+}
+inline void FieldDescriptorProto::set_json_name(const char* value) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), ::std::string(value));
+  // @@protoc_insertion_point(field_set_char:google.protobuf.FieldDescriptorProto.json_name)
+}
+inline void FieldDescriptorProto::set_json_name(const char* value, size_t size) {
+  set_has_json_name();
+  json_name_.SetNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(),
+      ::std::string(reinterpret_cast<const char*>(value), size));
+  // @@protoc_insertion_point(field_set_pointer:google.protobuf.FieldDescriptorProto.json_name)
+}
+inline ::std::string* FieldDescriptorProto::mutable_json_name() {
+  set_has_json_name();
+  // @@protoc_insertion_point(field_mutable:google.protobuf.FieldDescriptorProto.json_name)
+  return json_name_.MutableNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline ::std::string* FieldDescriptorProto::release_json_name() {
+  clear_has_json_name();
+  return json_name_.ReleaseNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited());
+}
+inline void FieldDescriptorProto::set_allocated_json_name(::std::string* json_name) {
+  if (json_name != NULL) {
+    set_has_json_name();
+  } else {
+    clear_has_json_name();
+  }
+  json_name_.SetAllocatedNoArena(&::google::protobuf::internal::GetEmptyStringAlreadyInited(), json_name);
+  // @@protoc_insertion_point(field_set_allocated:google.protobuf.FieldDescriptorProto.json_name)
+}
+
 // optional .google.protobuf.FieldOptions options = 8;
 inline bool FieldDescriptorProto::has_options() const {
-  return (_has_bits_[0] & 0x00000100u) != 0;
+  return (_has_bits_[0] & 0x00000200u) != 0;
 }
 inline void FieldDescriptorProto::set_has_options() {
-  _has_bits_[0] |= 0x00000100u;
+  _has_bits_[0] |= 0x00000200u;
 }
 inline void FieldDescriptorProto::clear_has_options() {
-  _has_bits_[0] &= ~0x00000100u;
+  _has_bits_[0] &= ~0x00000200u;
 }
 inline void FieldDescriptorProto::clear_options() {
   if (options_ != NULL) options_->::google::protobuf::FieldOptions::Clear();
diff --git a/src/google/protobuf/descriptor.proto b/src/google/protobuf/descriptor.proto
index 8f90a956..801d85e4 100644
--- a/src/google/protobuf/descriptor.proto
+++ b/src/google/protobuf/descriptor.proto
@@ -191,6 +191,12 @@ message FieldDescriptorProto {
   // list.  This field is a member of that oneof.
   optional int32 oneof_index = 9;
 
+  // JSON name of this field. The value is set by protocol compiler. If the
+  // user has set a "json_name" option on this field, that option's value
+  // will be used. Otherwise, it's deduced from the field's name by converting
+  // it to camelCase.
+  optional string json_name = 10;
+
   optional FieldOptions options = 8;
 }
 
diff --git a/src/google/protobuf/descriptor_database_unittest.cc b/src/google/protobuf/descriptor_database_unittest.cc
index a87fa049..1fc3816e 100644
--- a/src/google/protobuf/descriptor_database_unittest.cc
+++ b/src/google/protobuf/descriptor_database_unittest.cc
@@ -35,6 +35,10 @@
 // This file makes extensive use of RFC 3092.  :)
 
 #include <algorithm>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 
 #include <google/protobuf/descriptor_database.h>
 #include <google/protobuf/descriptor.h>
@@ -177,7 +181,7 @@ class DescriptorDatabaseTest
     EXPECT_FALSE(test_case_->AddToDatabase(file_proto));
   }
 
-  scoped_ptr<DescriptorDatabaseTestCase> test_case_;
+  google::protobuf::scoped_ptr<DescriptorDatabaseTestCase> test_case_;
   DescriptorDatabase* database_;
 };
 
diff --git a/src/google/protobuf/descriptor_unittest.cc b/src/google/protobuf/descriptor_unittest.cc
index e9b027db..ccd0650d 100644
--- a/src/google/protobuf/descriptor_unittest.cc
+++ b/src/google/protobuf/descriptor_unittest.cc
@@ -34,6 +34,10 @@
 //
 // This file makes extensive use of RFC 3092.  :)
 
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <vector>
 
 #include <google/protobuf/compiler/importer.h>
@@ -461,6 +465,16 @@ class DescriptorTest : public testing::Test {
     //     map<int32, int32> map_int32_int32 = 1;
     //   }
     //
+    //   // in "json.proto"
+    //   message TestMessage4 {
+    //     optional int32 field_name1 = 1;
+    //     optional int32 fieldName2 = 2;
+    //     optional int32 FieldName3 = 3;
+    //     optional int32 _field_name4 = 4;
+    //     optional int32 FIELD_NAME5 = 5;
+    //     optional int32 field_name6 = 6 [json_name = "@type"];
+    //   }
+    //
     // We cheat and use TestForeign as the type for qux rather than create
     // an actual nested type.
     //
@@ -526,6 +540,30 @@ class DescriptorTest : public testing::Test {
              FieldDescriptorProto::TYPE_MESSAGE)
         ->set_type_name("MapInt32Int32Entry");
 
+    FileDescriptorProto json_file;
+    json_file.set_name("json.proto");
+    json_file.set_syntax("proto3");
+    DescriptorProto* message4 = AddMessage(&json_file, "TestMessage4");
+    AddField(message4, "field_name1", 1,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32);
+    AddField(message4, "fieldName2", 2,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32);
+    AddField(message4, "FieldName3", 3,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32);
+    AddField(message4, "_field_name4", 4,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32);
+    AddField(message4, "FIELD_NAME5", 5,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32);
+    AddField(message4, "field_name6", 6,
+             FieldDescriptorProto::LABEL_OPTIONAL,
+             FieldDescriptorProto::TYPE_INT32)
+        ->set_json_name("@type");
+
     // Build the descriptors and get the pointers.
     foo_file_ = pool_.BuildFile(foo_file);
     ASSERT_TRUE(foo_file_ != NULL);
@@ -536,6 +574,9 @@ class DescriptorTest : public testing::Test {
     map_file_ = pool_.BuildFile(map_file);
     ASSERT_TRUE(map_file_ != NULL);
 
+    json_file_ = pool_.BuildFile(json_file);
+    ASSERT_TRUE(json_file_ != NULL);
+
     ASSERT_EQ(1, foo_file_->enum_type_count());
     enum_ = foo_file_->enum_type(0);
 
@@ -562,6 +603,14 @@ class DescriptorTest : public testing::Test {
 
     ASSERT_EQ(1, message3_->field_count());
     map_  = message3_->field(0);
+
+    ASSERT_EQ(1, json_file_->message_type_count());
+    message4_ = json_file_->message_type(0);
+  }
+
+  void CopyWithJsonName(const Descriptor* message, DescriptorProto* proto) {
+    message->CopyTo(proto);
+    message->CopyJsonNameTo(proto);
   }
 
   DescriptorPool pool_;
@@ -569,10 +618,12 @@ class DescriptorTest : public testing::Test {
   const FileDescriptor* foo_file_;
   const FileDescriptor* bar_file_;
   const FileDescriptor* map_file_;
+  const FileDescriptor* json_file_;
 
   const Descriptor* message_;
   const Descriptor* message2_;
   const Descriptor* message3_;
+  const Descriptor* message4_;
   const Descriptor* foreign_;
   const EnumDescriptor* enum_;
 
@@ -664,6 +715,35 @@ TEST_F(DescriptorTest, FieldFullName) {
   EXPECT_EQ("corge.grault.TestMessage2.quux", quux2_->full_name());
 }
 
+TEST_F(DescriptorTest, FieldJsonName) {
+  EXPECT_EQ("fieldName1", message4_->field(0)->json_name());
+  EXPECT_EQ("fieldName2", message4_->field(1)->json_name());
+  EXPECT_EQ("fieldName3", message4_->field(2)->json_name());
+  EXPECT_EQ("fieldName4", message4_->field(3)->json_name());
+  EXPECT_EQ("fIELDNAME5", message4_->field(4)->json_name());
+  EXPECT_EQ("@type", message4_->field(5)->json_name());
+
+  DescriptorProto proto;
+  message4_->CopyTo(&proto);
+  ASSERT_EQ(6, proto.field_size());
+  EXPECT_FALSE(proto.field(0).has_json_name());
+  EXPECT_FALSE(proto.field(1).has_json_name());
+  EXPECT_FALSE(proto.field(2).has_json_name());
+  EXPECT_FALSE(proto.field(3).has_json_name());
+  EXPECT_FALSE(proto.field(4).has_json_name());
+  EXPECT_EQ("@type", proto.field(5).json_name());
+
+  proto.Clear();
+  CopyWithJsonName(message4_, &proto);
+  ASSERT_EQ(6, proto.field_size());
+  EXPECT_EQ("fieldName1", proto.field(0).json_name());
+  EXPECT_EQ("fieldName2", proto.field(1).json_name());
+  EXPECT_EQ("fieldName3", proto.field(2).json_name());
+  EXPECT_EQ("fieldName4", proto.field(3).json_name());
+  EXPECT_EQ("fIELDNAME5", proto.field(4).json_name());
+  EXPECT_EQ("@type", proto.field(5).json_name());
+}
+
 TEST_F(DescriptorTest, FieldFile) {
   EXPECT_EQ(foo_file_, foo_->file());
   EXPECT_EQ(foo_file_, bar_->file());
@@ -1900,7 +1980,7 @@ class MiscTest : public testing::Test {
     return field != NULL ? field->enum_type() : NULL;
   }
 
-  scoped_ptr<DescriptorPool> pool_;
+  google::protobuf::scoped_ptr<DescriptorPool> pool_;
 };
 
 TEST_F(MiscTest, TypeNames) {
@@ -2330,7 +2410,7 @@ class AllowUnknownDependenciesTest
   const FieldDescriptor* qux_field_;
 
   SimpleDescriptorDatabase db_;        // used if in FALLBACK_DATABASE mode.
-  scoped_ptr<DescriptorPool> pool_;
+  google::protobuf::scoped_ptr<DescriptorPool> pool_;
 };
 
 TEST_P(AllowUnknownDependenciesTest, PlaceholderFile) {
@@ -5681,6 +5761,32 @@ TEST_F(ValidationErrorTest, ValidateProto3Extension) {
       "defining options.\n");
 }
 
+// Test that field names that may conflict in JSON is not allowed by protoc.
+TEST_F(ValidationErrorTest, ValidateProto3JsonName) {
+  // The comparison is case-insensitive.
+  BuildFileWithErrors(
+      "name: 'foo.proto' "
+      "syntax: 'proto3' "
+      "message_type {"
+      "  name: 'Foo'"
+      "  field { name:'name' number:1 label:LABEL_OPTIONAL type:TYPE_INT32 }"
+      "  field { name:'Name' number:2 label:LABEL_OPTIONAL type:TYPE_INT32 }"
+      "}",
+      "foo.proto: Foo: OTHER: The JSON camcel-case name of field \"Name\" "
+      "conflicts with field \"name\". This is not allowed in proto3.\n");
+  // Underscores are ignored.
+  BuildFileWithErrors(
+      "name: 'foo.proto' "
+      "syntax: 'proto3' "
+      "message_type {"
+      "  name: 'Foo'"
+      "  field { name:'ab' number:1 label:LABEL_OPTIONAL type:TYPE_INT32 }"
+      "  field { name:'_a__b_' number:2 label:LABEL_OPTIONAL type:TYPE_INT32 }"
+      "}",
+      "foo.proto: Foo: OTHER: The JSON camcel-case name of field \"_a__b_\" "
+      "conflicts with field \"ab\". This is not allowed in proto3.\n");
+}
+
 // ===================================================================
 // DescriptorDatabase
 
diff --git a/src/google/protobuf/dynamic_message.cc b/src/google/protobuf/dynamic_message.cc
index 2324d952..091fc975 100644
--- a/src/google/protobuf/dynamic_message.cc
+++ b/src/google/protobuf/dynamic_message.cc
@@ -64,6 +64,10 @@
 
 #include <algorithm>
 #include <google/protobuf/stubs/hash.h>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 
 #include <google/protobuf/stubs/scoped_ptr.h>
 #include <google/protobuf/stubs/common.h>
@@ -229,8 +233,8 @@ class DynamicMessage : public Message {
 
     // Warning:  The order in which the following pointers are defined is
     //   important (the prototype must be deleted *before* the offsets).
-    scoped_array<int> offsets;
-    scoped_ptr<const GeneratedMessageReflection> reflection;
+    google::protobuf::scoped_array<int> offsets;
+    google::protobuf::scoped_ptr<const GeneratedMessageReflection> reflection;
     // Don't use a scoped_ptr to hold the prototype: the destructor for
     // DynamicMessage needs to know whether it is the prototype, and does so by
     // looking back at this field. This would assume details about the
diff --git a/src/google/protobuf/dynamic_message_unittest.cc b/src/google/protobuf/dynamic_message_unittest.cc
index b9796c76..70e437d7 100644
--- a/src/google/protobuf/dynamic_message_unittest.cc
+++ b/src/google/protobuf/dynamic_message_unittest.cc
@@ -40,6 +40,11 @@
 // reflection_ops_unittest, cover the rest of the functionality used by
 // DynamicMessage.
 
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
+
 #include <google/protobuf/stubs/scoped_ptr.h>
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/dynamic_message.h>
@@ -144,7 +149,7 @@ TEST_F(DynamicMessageTest, IndependentOffsets) {
   // Check that all fields have independent offsets by setting each
   // one to a unique value then checking that they all still have those
   // unique values (i.e. they don't stomp each other).
-  scoped_ptr<Message> message(prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(prototype_->New());
   TestUtil::ReflectionTester reflection_tester(descriptor_);
 
   reflection_tester.SetAllFieldsViaReflection(message.get());
@@ -153,7 +158,7 @@ TEST_F(DynamicMessageTest, IndependentOffsets) {
 
 TEST_F(DynamicMessageTest, Extensions) {
   // Check that extensions work.
-  scoped_ptr<Message> message(extensions_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(extensions_prototype_->New());
   TestUtil::ReflectionTester reflection_tester(extensions_descriptor_);
 
   reflection_tester.SetAllFieldsViaReflection(message.get());
@@ -162,7 +167,7 @@ TEST_F(DynamicMessageTest, Extensions) {
 
 TEST_F(DynamicMessageTest, PackedFields) {
   // Check that packed fields work properly.
-  scoped_ptr<Message> message(packed_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(packed_prototype_->New());
   TestUtil::ReflectionTester reflection_tester(packed_descriptor_);
 
   reflection_tester.SetPackedFieldsViaReflection(message.get());
@@ -171,7 +176,7 @@ TEST_F(DynamicMessageTest, PackedFields) {
 
 TEST_F(DynamicMessageTest, Oneof) {
   // Check that oneof fields work properly.
-  scoped_ptr<Message> message(oneof_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(oneof_prototype_->New());
 
   // Check default values.
   const Descriptor* descriptor = message->GetDescriptor();
@@ -232,7 +237,7 @@ TEST_F(DynamicMessageTest, SpaceUsed) {
   // Since we share the implementation with generated messages, we don't need
   // to test very much here.  Just make sure it appears to be working.
 
-  scoped_ptr<Message> message(prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(prototype_->New());
   TestUtil::ReflectionTester reflection_tester(descriptor_);
 
   int initial_space_used = message->SpaceUsed();
diff --git a/src/google/protobuf/extension_set.cc b/src/google/protobuf/extension_set.cc
index 919bd83b..9afb2361 100644
--- a/src/google/protobuf/extension_set.cc
+++ b/src/google/protobuf/extension_set.cc
@@ -34,6 +34,7 @@
 
 #include <google/protobuf/stubs/hash.h>
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/once.h>
 #include <google/protobuf/extension_set.h>
 #include <google/protobuf/message_lite.h>
 #include <google/protobuf/io/coded_stream.h>
@@ -594,20 +595,21 @@ void ExtensionSet::SetAllocatedMessage(int number, FieldType type,
     ClearExtension(number);
     return;
   }
+  ::google::protobuf::Arena* message_arena = message->GetArena();
   Extension* extension;
   if (MaybeNewExtension(number, descriptor, &extension)) {
     extension->type = type;
     GOOGLE_DCHECK_EQ(cpp_type(extension->type), WireFormatLite::CPPTYPE_MESSAGE);
     extension->is_repeated = false;
     extension->is_lazy = false;
-    if (message->GetArena() == arena_) {
+    if (message_arena == arena_) {
       extension->message_value = message;
+    } else if (message_arena == NULL) {
+      extension->message_value = message;
+      arena_->Own(message);  // not NULL because not equal to message_arena
     } else {
       extension->message_value = message->New(arena_);
       extension->message_value->CheckTypeAndMergeFrom(*message);
-      if (message->GetArena() == NULL) {
-        delete message;
-      }
     }
   } else {
     GOOGLE_DCHECK_TYPE(*extension, OPTIONAL, MESSAGE);
@@ -617,14 +619,14 @@ void ExtensionSet::SetAllocatedMessage(int number, FieldType type,
       if (arena_ == NULL) {
         delete extension->message_value;
       }
-      if (message->GetArena() == arena_) {
+      if (message_arena == arena_) {
         extension->message_value = message;
+      } else if (message_arena == NULL) {
+        extension->message_value = message;
+        arena_->Own(message);  // not NULL because not equal to message_arena
       } else {
         extension->message_value = message->New(arena_);
         extension->message_value->CheckTypeAndMergeFrom(*message);
-        if (message->GetArena() == NULL) {
-          delete message;
-        }
       }
     }
   }
diff --git a/src/google/protobuf/extension_set.h b/src/google/protobuf/extension_set.h
index 09681259..40704608 100644
--- a/src/google/protobuf/extension_set.h
+++ b/src/google/protobuf/extension_set.h
@@ -724,8 +724,7 @@ class RepeatedPrimitiveTypeTraits {
   static const RepeatedFieldType* GetDefaultRepeatedField();
 };
 
-LIBPROTOBUF_EXPORT extern ProtobufOnceType
-repeated_primitive_generic_type_traits_once_init_;
+extern ProtobufOnceType repeated_primitive_generic_type_traits_once_init_;
 
 class LIBPROTOBUF_EXPORT RepeatedPrimitiveGenericTypeTraits {
  private:
@@ -766,7 +765,7 @@ template<> inline void RepeatedPrimitiveTypeTraits<TYPE>::Add(             \
 }                                                                          \
 template<> inline const RepeatedField<TYPE>*                               \
     RepeatedPrimitiveTypeTraits<TYPE>::GetDefaultRepeatedField() {         \
-  GoogleOnceInit(                                                          \
+  ::google::protobuf::GoogleOnceInit(                                                          \
       &repeated_primitive_generic_type_traits_once_init_,                  \
       &RepeatedPrimitiveGenericTypeTraits::InitializeDefaultRepeatedFields); \
   return RepeatedPrimitiveGenericTypeTraits::                              \
@@ -822,8 +821,7 @@ class LIBPROTOBUF_EXPORT StringTypeTraits {
   }
 };
 
-LIBPROTOBUF_EXPORT extern ProtobufOnceType
-repeated_string_type_traits_once_init_;
+extern ProtobufOnceType repeated_string_type_traits_once_init_;
 
 class LIBPROTOBUF_EXPORT RepeatedStringTypeTraits {
  public:
@@ -868,7 +866,7 @@ class LIBPROTOBUF_EXPORT RepeatedStringTypeTraits {
   }
 
   static const RepeatedFieldType* GetDefaultRepeatedField() {
-    GoogleOnceInit(&repeated_string_type_traits_once_init_,
+    ::google::protobuf::GoogleOnceInit(&repeated_string_type_traits_once_init_,
                    &InitializeDefaultRepeatedFields);
     return default_repeated_field_;
   }
@@ -1034,8 +1032,7 @@ class RepeatedMessageTypeTraits {
   static const RepeatedFieldType* GetDefaultRepeatedField();
 };
 
-LIBPROTOBUF_EXPORT extern ProtobufOnceType
-repeated_message_generic_type_traits_once_init_;
+extern ProtobufOnceType repeated_message_generic_type_traits_once_init_;
 
 // This class exists only to hold a generic default empty repeated field for all
 // message-type repeated field extensions.
@@ -1052,7 +1049,7 @@ class LIBPROTOBUF_EXPORT RepeatedMessageGenericTypeTraits {
 template<typename Type> inline
     const typename RepeatedMessageTypeTraits<Type>::RepeatedFieldType*
     RepeatedMessageTypeTraits<Type>::GetDefaultRepeatedField() {
-  GoogleOnceInit(
+  ::google::protobuf::GoogleOnceInit(
       &repeated_message_generic_type_traits_once_init_,
       &RepeatedMessageGenericTypeTraits::InitializeDefaultRepeatedFields);
   return reinterpret_cast<const RepeatedFieldType*>(
diff --git a/src/google/protobuf/extension_set_unittest.cc b/src/google/protobuf/extension_set_unittest.cc
index 1569120d..f40fcbc2 100644
--- a/src/google/protobuf/extension_set_unittest.cc
+++ b/src/google/protobuf/extension_set_unittest.cc
@@ -360,9 +360,8 @@ TEST(ExtensionSetTest, ArenaSetAllocatedMessageAndRelease) {
   unittest::ForeignMessage* foreign_message = new unittest::ForeignMessage();
   message->SetAllocatedExtension(unittest::optional_foreign_message_extension,
                                  foreign_message);
-  // foreign_message is copied underneath, as foreign_message is on heap
-  // and extension_set is on an arena.
-  EXPECT_NE(foreign_message,
+  // foreign_message is now owned by the arena.
+  EXPECT_EQ(foreign_message,
             message->MutableExtension(
                 unittest::optional_foreign_message_extension));
 
diff --git a/src/google/protobuf/generated_message_reflection_unittest.cc b/src/google/protobuf/generated_message_reflection_unittest.cc
index df043844..85ebdef1 100644
--- a/src/google/protobuf/generated_message_reflection_unittest.cc
+++ b/src/google/protobuf/generated_message_reflection_unittest.cc
@@ -43,6 +43,11 @@
 // rather than generated accessors.
 
 #include <google/protobuf/generated_message_reflection.h>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
+
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/test_util.h>
 #include <google/protobuf/unittest.pb.h>
@@ -354,7 +359,7 @@ TEST(GeneratedMessageReflectionTest, ReleaseLast) {
   ASSERT_EQ(2, message.repeated_foreign_message_size());
   const protobuf_unittest::ForeignMessage* expected =
       message.mutable_repeated_foreign_message(1);
-  scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
+  google::protobuf::scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
       &message, descriptor->FindFieldByName("repeated_foreign_message")));
   EXPECT_EQ(expected, released.get());
 }
@@ -377,9 +382,9 @@ TEST(GeneratedMessageReflectionTest, ReleaseLastExtensions) {
       unittest::repeated_foreign_message_extension));
   const protobuf_unittest::ForeignMessage* expected = message.MutableExtension(
       unittest::repeated_foreign_message_extension, 1);
-  scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
+  google::protobuf::scoped_ptr<Message> released(message.GetReflection()->ReleaseLast(
       &message, descriptor->file()->FindExtensionByName(
-          "repeated_foreign_message_extension")));
+                    "repeated_foreign_message_extension")));
   EXPECT_EQ(expected, released.get());
 
 }
diff --git a/src/google/protobuf/generated_message_util.cc b/src/google/protobuf/generated_message_util.cc
index afaca2ee..7b813f8a 100644
--- a/src/google/protobuf/generated_message_util.cc
+++ b/src/google/protobuf/generated_message_util.cc
@@ -63,7 +63,6 @@ void InitEmptyString() {
 int StringSpaceUsedExcludingSelf(const string& str) {
   const void* start = &str;
   const void* end = &str + 1;
-
   if (start <= str.data() && str.data() < end) {
     // The string's data is stored inside the string object itself.
     return 0;
@@ -73,6 +72,7 @@ int StringSpaceUsedExcludingSelf(const string& str) {
 }
 
 
+
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/io/coded_stream_unittest.cc b/src/google/protobuf/io/coded_stream_unittest.cc
index 630c9086..d1782e39 100644
--- a/src/google/protobuf/io/coded_stream_unittest.cc
+++ b/src/google/protobuf/io/coded_stream_unittest.cc
@@ -34,6 +34,10 @@
 //
 // This file contains tests and benchmarks.
 
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <vector>
 
 #include <google/protobuf/io/coded_stream.h>
@@ -679,7 +683,7 @@ TEST_F(CodedStreamTest, ReadStringImpossiblyLargeFromStringOnStack) {
 }
 
 TEST_F(CodedStreamTest, ReadStringImpossiblyLargeFromStringOnHeap) {
-  scoped_array<uint8> buffer(new uint8[8]);
+  google::protobuf::scoped_array<uint8> buffer(new uint8[8]);
   CodedInputStream coded_input(buffer.get(), 8);
   string str;
   EXPECT_FALSE(coded_input.ReadString(&str, 1 << 30));
diff --git a/src/google/protobuf/io/zero_copy_stream_impl_lite.h b/src/google/protobuf/io/zero_copy_stream_impl_lite.h
index 9cdf0378..a598ef2e 100644
--- a/src/google/protobuf/io/zero_copy_stream_impl_lite.h
+++ b/src/google/protobuf/io/zero_copy_stream_impl_lite.h
@@ -44,6 +44,10 @@
 #ifndef GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_LITE_H__
 #define GOOGLE_PROTOBUF_IO_ZERO_COPY_STREAM_IMPL_LITE_H__
 
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <string>
 #include <iosfwd>
 #include <google/protobuf/io/zero_copy_stream.h>
@@ -235,7 +239,7 @@ class LIBPROTOBUF_EXPORT CopyingInputStreamAdaptor : public ZeroCopyInputStream
 
   // Data is read into this buffer.  It may be NULL if no buffer is currently
   // in use.  Otherwise, it points to an array of size buffer_size_.
-  scoped_array<uint8> buffer_;
+  google::protobuf::scoped_array<uint8> buffer_;
   const int buffer_size_;
 
   // Number of valid bytes currently in the buffer (i.e. the size last
@@ -324,7 +328,7 @@ class LIBPROTOBUF_EXPORT CopyingOutputStreamAdaptor : public ZeroCopyOutputStrea
 
   // Data is written from this buffer.  It may be NULL if no buffer is
   // currently in use.  Otherwise, it points to an array of size buffer_size_.
-  scoped_array<uint8> buffer_;
+  google::protobuf::scoped_array<uint8> buffer_;
   const int buffer_size_;
 
   // Number of valid bytes currently in the buffer (i.e. the size last
diff --git a/src/google/protobuf/io/zero_copy_stream_unittest.cc b/src/google/protobuf/io/zero_copy_stream_unittest.cc
index 3850e76c..8c7358c1 100644
--- a/src/google/protobuf/io/zero_copy_stream_unittest.cc
+++ b/src/google/protobuf/io/zero_copy_stream_unittest.cc
@@ -57,6 +57,10 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 #include <sstream>
 
 #include <google/protobuf/io/zero_copy_stream_impl.h>
@@ -197,7 +201,7 @@ void IoTest::WriteString(ZeroCopyOutputStream* output, const string& str) {
 }
 
 void IoTest::ReadString(ZeroCopyInputStream* input, const string& str) {
-  scoped_array<char> buffer(new char[str.size() + 1]);
+  google::protobuf::scoped_array<char> buffer(new char[str.size() + 1]);
   buffer[str.size()] = '\0';
   EXPECT_EQ(ReadFromInput(input, buffer.get(), str.size()), str.size());
   EXPECT_STREQ(str.c_str(), buffer.get());
diff --git a/src/google/protobuf/map_field_inl.h b/src/google/protobuf/map_field_inl.h
index 16c4a08f..f116697c 100644
--- a/src/google/protobuf/map_field_inl.h
+++ b/src/google/protobuf/map_field_inl.h
@@ -155,7 +155,8 @@ void TypeDefinedMapFieldBase<Key, T>::CopyIterator(
   this_iter->key_.SetType(that_iter.key_.type());
   // MapValueRef::type() fails when containing data is null. However, if
   // this_iter points to MapEnd, data can be null.
-  this_iter->value_.SetType((FieldDescriptor::CppType)that_iter.value_.type_);
+  this_iter->value_.SetType(
+      static_cast<FieldDescriptor::CppType>(that_iter.value_.type_));
   SetMapIteratorValue(this_iter);
 }
 
diff --git a/src/google/protobuf/map_proto2_unittest.proto b/src/google/protobuf/map_proto2_unittest.proto
index 6f9d6165..916cc546 100644
--- a/src/google/protobuf/map_proto2_unittest.proto
+++ b/src/google/protobuf/map_proto2_unittest.proto
@@ -31,6 +31,8 @@
 syntax = "proto2";
 
 
+import "google/protobuf/unittest_import.proto";
+
 // We don't put this in a package within proto2 because we need to make sure
 // that the generated code doesn't depend on being in the proto2 namespace.
 // In map_test_util.h we do "using namespace unittest = protobuf_unittest".
@@ -58,3 +60,7 @@ message TestEnumMapPlusExtra {
   map<int32, Proto2MapEnumPlusExtra> known_map_field = 101;
   map<int32, Proto2MapEnumPlusExtra> unknown_map_field = 102;
 }
+
+message TestImportEnumMap {
+  map<int32, protobuf_unittest_import.ImportEnumForMap> import_enum_amp = 1;
+}
diff --git a/src/google/protobuf/map_test.cc b/src/google/protobuf/map_test.cc
index 16a24c25..451b02e8 100644
--- a/src/google/protobuf/map_test.cc
+++ b/src/google/protobuf/map_test.cc
@@ -2154,7 +2154,7 @@ TEST_F(MapFieldInDynamicMessageTest, MapIndependentOffsets) {
   // Check that all fields have independent offsets by setting each
   // one to a unique value then checking that they all still have those
   // unique values (i.e. they don't stomp each other).
-  scoped_ptr<Message> message(map_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(map_prototype_->New());
   MapReflectionTester reflection_tester(map_descriptor_);
 
   reflection_tester.SetMapFieldsViaReflection(message.get());
@@ -2163,7 +2163,7 @@ TEST_F(MapFieldInDynamicMessageTest, MapIndependentOffsets) {
 
 TEST_F(MapFieldInDynamicMessageTest, DynamicMapReflection) {
   // Check that map fields work properly.
-  scoped_ptr<Message> message(map_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(map_prototype_->New());
 
   // Check set functions.
   MapReflectionTester reflection_tester(map_descriptor_);
@@ -2177,7 +2177,7 @@ TEST_F(MapFieldInDynamicMessageTest, MapSpaceUsed) {
   // Since we share the implementation with generated messages, we don't need
   // to test very much here.  Just make sure it appears to be working.
 
-  scoped_ptr<Message> message(map_prototype_->New());
+  google::protobuf::scoped_ptr<Message> message(map_prototype_->New());
   MapReflectionTester reflection_tester(map_descriptor_);
 
   int initial_space_used = message->SpaceUsed();
diff --git a/src/google/protobuf/message.cc b/src/google/protobuf/message.cc
index 2f6416d0..d9c200c6 100644
--- a/src/google/protobuf/message.cc
+++ b/src/google/protobuf/message.cc
@@ -55,7 +55,6 @@
 #include <google/protobuf/stubs/map_util.h>
 #include <google/protobuf/stubs/singleton.h>
 #include <google/protobuf/stubs/stl_util.h>
-#include <google/protobuf/stubs/port.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/message.h b/src/google/protobuf/message.h
index 348e7c7f..7c27afd9 100644
--- a/src/google/protobuf/message.h
+++ b/src/google/protobuf/message.h
@@ -971,7 +971,7 @@ class LIBPROTOBUF_EXPORT Reflection {
     return false;
   }
 
-  // Returns a MaIterator referring to the first element in the map field.
+  // Returns a MapIterator referring to the first element in the map field.
   // If the map field is empty, this function returns the same as
   // reflection::MapEnd. Mutation to the field may invalidate the iterator.
   virtual MapIterator MapBegin(
diff --git a/src/google/protobuf/repeated_field.h b/src/google/protobuf/repeated_field.h
index b10e7a95..5530fefe 100644
--- a/src/google/protobuf/repeated_field.h
+++ b/src/google/protobuf/repeated_field.h
@@ -649,7 +649,7 @@ inline const Message& GenericTypeHandler<Message>::default_instance() {
 //   StringTypeHandler is exported.  So, we factor out StringTypeHandlerBase,
 //   export that, then make StringTypeHandler be a subclass which is NOT
 //   exported.
-// TODO(kenton):  Now that StringSpaceUsedExcludingSelf() is in the lite

+// TODO(kenton):  Now that StringSpaceUsedExcludingSelf() is in the lite
 //   library, this can be cleaned up.
 class LIBPROTOBUF_EXPORT StringTypeHandlerBase {
  public:
diff --git a/src/google/protobuf/stubs/stringpiece.h b/src/google/protobuf/stubs/stringpiece.h
index 353a60d3..ec3ffd5b 100644
--- a/src/google/protobuf/stubs/stringpiece.h
+++ b/src/google/protobuf/stubs/stringpiece.h
@@ -149,6 +149,7 @@
 #include <string>
 
 #include <google/protobuf/stubs/common.h>
+#include <google/protobuf/stubs/hash.h>
 
 namespace google {
 namespace protobuf {
@@ -437,4 +438,16 @@ extern std::ostream& operator<<(std::ostream& o, StringPiece piece);
 }  // namespace protobuf
 }  // namespace google
 
+GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_START
+template<> struct hash<StringPiece> {
+  size_t operator()(const StringPiece& s) const {
+    size_t result = 0;
+    for (const char *str = s.data(), *end = str + s.size(); str < end; str++) {  
+      result = 5 * result + *str;
+    }
+    return result;
+  }
+};
+GOOGLE_PROTOBUF_HASH_NAMESPACE_DECLARATION_END
+
 #endif  // STRINGS_STRINGPIECE_H_
diff --git a/src/google/protobuf/stubs/stringpiece_unittest.cc b/src/google/protobuf/stubs/stringpiece_unittest.cc
index 9b5dae13..1cb7d12b 100644
--- a/src/google/protobuf/stubs/stringpiece_unittest.cc
+++ b/src/google/protobuf/stubs/stringpiece_unittest.cc
@@ -30,6 +30,7 @@
 #include <google/protobuf/stubs/stringpiece.h>
 
 #include <iterator>
+#include <hash_set>
 #include <map>
 #include <string>
 #include <utility>
@@ -745,6 +746,23 @@ TEST(StringPiece, Comparisons2) {
   EXPECT_TRUE(abc.ends_with("nopqrstuvwxyz"));
 }
 
+TEST(StringPiece, HashFunction) {
+  hash_set<StringPiece> set;
+
+  set.insert(StringPiece("hello"));
+  EXPECT_EQ(1, set.size());
+
+  // Insert a StringPiece of the same value again and should NOT increment
+  // size of the set.
+  set.insert(StringPiece("hello"));
+  EXPECT_EQ(1, set.size());
+
+  // Insert a StringPiece with different value and check that size of the set
+  // has been increment by one.
+  set.insert(StringPiece("world"));
+  EXPECT_EQ(2, set.size());
+}
+
 TEST(ComparisonOpsTest, StringCompareNotAmbiguous) {
   EXPECT_EQ("hello", string("hello"));
   EXPECT_LT("hello", string("world"));
diff --git a/src/google/protobuf/text_format.cc b/src/google/protobuf/text_format.cc
index 4d8c1f91..38b9069b 100644
--- a/src/google/protobuf/text_format.cc
+++ b/src/google/protobuf/text_format.cc
@@ -377,8 +377,8 @@ class TextFormat::Parser::ParserImpl {
     if (internal::GetAnyFieldDescriptors(*message, &any_type_url_field,
                                          &any_value_field) &&
         TryConsume("[")) {
-      string full_type_name;
-      DO(ConsumeAnyTypeUrl(&full_type_name));
+      string full_type_name, prefix;
+      DO(ConsumeAnyTypeUrl(&full_type_name, &prefix));
       DO(Consume("]"));
       string serialized_value;
       DO(ConsumeAnyValue(full_type_name,
@@ -386,7 +386,7 @@ class TextFormat::Parser::ParserImpl {
                          &serialized_value));
       reflection->SetString(
           message, any_type_url_field,
-          string(internal::kTypeGoogleApisComPrefix) + full_type_name);
+          string(prefix + full_type_name));
       reflection->SetString(message, any_value_field, serialized_value);
       return true;
       // Fall through.
@@ -981,7 +981,8 @@ class TextFormat::Parser::ParserImpl {
   }
 
   // Consumes Any::type_url value, of form "type.googleapis.com/full.type.Name"
-  bool ConsumeAnyTypeUrl(string* full_type_name) {
+  // or "type.googleprod.com/full.type.Name"
+  bool ConsumeAnyTypeUrl(string* full_type_name, string* prefix) {
     // TODO(saito) Extend Consume() to consume multiple tokens at once, so that
     // this code can be written as just DO(Consume(kGoogleApisTypePrefix)).
     string url1, url2, url3;
@@ -993,10 +994,12 @@ class TextFormat::Parser::ParserImpl {
     DO(Consume("/"));
     DO(ConsumeFullTypeName(full_type_name));
 
-    const string prefix = url1 + "." + url2 + "." + url3 + "/";
-    if (prefix != internal::kTypeGoogleApisComPrefix) {
+    *prefix = url1 + "." + url2 + "." + url3 + "/";
+    if (*prefix != internal::kTypeGoogleApisComPrefix &&
+        *prefix != internal::kTypeGoogleProdComPrefix) {
       ReportError("TextFormat::Parser for Any supports only "
-                  "type.googleapi.com, but found \"" + prefix + "\"");
+                  "type.googleapis.com and type.googleprod.com, "
+                  "but found \"" + *prefix + "\"");
       return false;
     }
     return true;
diff --git a/src/google/protobuf/text_format_unittest.cc b/src/google/protobuf/text_format_unittest.cc
index 1aafd8e6..8d61be19 100644
--- a/src/google/protobuf/text_format_unittest.cc
+++ b/src/google/protobuf/text_format_unittest.cc
@@ -37,6 +37,10 @@
 #include <math.h>
 #include <stdlib.h>
 #include <limits>
+#include <memory>
+#ifndef _SHARED_PTR_H
+#include <google/protobuf/stubs/shared_ptr.h>
+#endif
 
 #include <google/protobuf/stubs/logging.h>
 #include <google/protobuf/stubs/common.h>
@@ -931,7 +935,7 @@ class TextFormatParserTest : public testing::Test {
  protected:
   void ExpectFailure(const string& input, const string& message, int line,
                      int col) {
-    scoped_ptr<unittest::TestAllTypes> proto(new unittest::TestAllTypes);
+    google::protobuf::scoped_ptr<unittest::TestAllTypes> proto(new unittest::TestAllTypes);
     ExpectFailure(input, message, line, col, proto.get());
   }
 
@@ -992,7 +996,7 @@ class TextFormatParserTest : public testing::Test {
 };
 
 TEST_F(TextFormatParserTest, ParseInfoTreeBuilding) {
-  scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
+  google::protobuf::scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
   const Descriptor* d = message->GetDescriptor();
 
   string stringData =
@@ -1057,7 +1061,7 @@ TEST_F(TextFormatParserTest, ParseInfoTreeBuilding) {
 }
 
 TEST_F(TextFormatParserTest, ParseFieldValueFromString) {
-  scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
+  google::protobuf::scoped_ptr<unittest::TestAllTypes> message(new unittest::TestAllTypes);
   const Descriptor* d = message->GetDescriptor();
 
 #define EXPECT_FIELD(name, value, valuestring) \
diff --git a/src/google/protobuf/unittest_import.proto b/src/google/protobuf/unittest_import.proto
index 7e165220..8d03e388 100644
--- a/src/google/protobuf/unittest_import.proto
+++ b/src/google/protobuf/unittest_import.proto
@@ -64,3 +64,10 @@ enum ImportEnum {
   IMPORT_BAZ = 9;
 }
 
+
+// To use an enum in a map, it must has the first value as 0.
+enum ImportEnumForMap {
+  UNKNOWN = 0;
+  FOO = 1;
+  BAR = 2;
+}
diff --git a/src/google/protobuf/util/default_value_objectwriter.h b/src/google/protobuf/util/default_value_objectwriter.h
new file mode 100644
index 00000000..11b9f801
--- /dev/null
+++ b/src/google/protobuf/util/default_value_objectwriter.h
@@ -0,0 +1,218 @@
+#ifndef NET_PROTO2_UTIL_CONVERTER_INTERNAL_DEFAULT_VALUE_OBJECTWRITER_H_
+#define NET_PROTO2_UTIL_CONVERTER_INTERNAL_DEFAULT_VALUE_OBJECTWRITER_H_
+
+#include <memory>
+#include <stack>
+#include <vector>
+
+#include "base/macros.h"
+#include "net/proto2/util/converter/internal/type_info.h"
+#include "net/proto2/util/converter/public/datapiece.h"
+#include "net/proto2/util/converter/public/object_writer.h"
+#include "net/proto2/util/converter/public/utility.h"
+#include "net/proto2/util/public/type_resolver.h"
+#include "strings/stringpiece.h"
+
+namespace proto2 {
+namespace util {
+namespace converter {
+
+// An ObjectWriter that renders non-repeated primitive fields of proto messages
+// with their default values. DefaultValueObjectWriter holds objects, lists and
+// fields it receives in a tree structure and writes them out to another
+// ObjectWriter when EndObject() is called on the root object. It also writes
+// out all non-repeated primitive fields that haven't been explicitly rendered
+// with their default values (0 for numbers, "" for strings, etc).
+class DefaultValueObjectWriter : public ObjectWriter {
+ public:
+#ifndef PROTO2_OPENSOURCE
+  DefaultValueObjectWriter(const TypeInfo& typeinfo,
+                           const google::protobuf::Type& type,
+                           ObjectWriter* ow);
+#endif  // !PROTO2_OPENSOURCE
+  DefaultValueObjectWriter(TypeResolver* type_resolver,
+                           const google::protobuf::Type& type,
+                           ObjectWriter* ow);
+
+  virtual ~DefaultValueObjectWriter();
+
+  // ObjectWriter methods.
+  virtual DefaultValueObjectWriter* StartObject(StringPiece name);
+
+  virtual DefaultValueObjectWriter* EndObject();
+
+  virtual DefaultValueObjectWriter* StartList(StringPiece name);
+
+  virtual DefaultValueObjectWriter* EndList();
+
+  virtual DefaultValueObjectWriter* RenderBool(StringPiece name, bool value);
+
+  virtual DefaultValueObjectWriter* RenderInt32(StringPiece name, int32 value);
+
+  virtual DefaultValueObjectWriter* RenderUint32(StringPiece name,
+                                                 uint32 value);
+
+  virtual DefaultValueObjectWriter* RenderInt64(StringPiece name, int64 value);
+
+  virtual DefaultValueObjectWriter* RenderUint64(StringPiece name,
+                                                 uint64 value);
+
+  virtual DefaultValueObjectWriter* RenderDouble(StringPiece name,
+                                                 double value);
+
+  virtual DefaultValueObjectWriter* RenderFloat(StringPiece name, float value);
+
+  virtual DefaultValueObjectWriter* RenderString(StringPiece name,
+                                                 StringPiece value);
+#ifdef PROTO2_OPENSOURCE
+  virtual DefaultValueObjectWriter* RenderBytes(StringPiece name,
+                                                StringPiece value);
+#else   // PROTO2_OPENSOURCE
+  virtual DefaultValueObjectWriter* RenderCord(StringPiece name,
+                                               const Cord& value);
+#endif  // !PROTO2_OPENSOURCE
+
+  virtual DefaultValueObjectWriter* RenderNull(StringPiece name);
+
+  virtual DefaultValueObjectWriter* DisableCaseNormalizationForNextKey();
+
+ private:
+  enum NodeKind {
+    PRIMITIVE = 0,
+    OBJECT = 1,
+    LIST = 2,
+    MAP = 3,
+  };
+
+  // "Node" represents a node in the tree that holds the input of
+  // DefaultValueObjectWriter.
+  class Node {
+   public:
+    Node(const string& name, const google::protobuf::Type* type, NodeKind kind,
+         const DataPiece& data, bool is_placeholder);
+    virtual ~Node() {
+      for (int i = 0; i < children_.size(); ++i) {
+        delete children_[i];
+      }
+    }
+
+    // Adds a child to this node. Takes ownership of this child.
+    void AddChild(Node* child) { children_.push_back(child); }
+
+    // Finds the child given its name.
+    Node* FindChild(StringPiece name);
+
+    // Populates children of this Node based on its type. If there are already
+    // children created, they will be merged to the result. Caller should pass
+    // in TypeInfo for looking up types of the children.
+    void PopulateChildren(const TypeInfo* typeinfo);
+
+    // If this node is a leaf (has data), writes the current node to the
+    // ObjectWriter; if not, then recursively writes the children to the
+    // ObjectWriter.
+    void WriteTo(ObjectWriter* ow);
+
+    // Accessors
+    const string& name() const { return name_; }
+
+    const google::protobuf::Type* type() { return type_; }
+
+    void set_type(const google::protobuf::Type* type) { type_ = type; }
+
+    NodeKind kind() { return kind_; }
+
+    int number_of_children() { return children_.size(); }
+
+    void set_data(const DataPiece& data) { data_ = data; }
+
+    void set_disable_normalize(bool disable_normalize) {
+      disable_normalize_ = disable_normalize;
+    }
+
+    bool is_any() { return is_any_; }
+
+    void set_is_any(bool is_any) { is_any_ = is_any; }
+
+    void set_is_placeholder(bool is_placeholder) {
+      is_placeholder_ = is_placeholder;
+    }
+
+   private:
+    // Returns the Value Type of a map given the Type of the map entry and a
+    // TypeInfo instance.
+    const google::protobuf::Type* GetMapValueType(
+        const google::protobuf::Type& entry_type, const TypeInfo* typeinfo);
+
+    // Calls WriteTo() on every child in children_.
+    void WriteChildren(ObjectWriter* ow);
+
+    // The name of this node.
+    string name_;
+    // google::protobuf::Type of this node. Owned by TypeInfo.
+    const google::protobuf::Type* type_;
+    // The kind of this node.
+    NodeKind kind_;
+    // Whether to disable case normalization of the name.
+    bool disable_normalize_;
+    // Whether this is a node for "Any".
+    bool is_any_;
+    // The data of this node when it is a leaf node.
+    DataPiece data_;
+    // Children of this node.
+    std::vector<Node*> children_;
+    // Whether this node is a placeholder for an object or list automatically
+    // generated when creating the parent node. Should be set to false after
+    // the parent node's StartObject()/StartList() method is called with this
+    // node's name.
+    bool is_placeholder_;
+  };
+
+  // Populates children of "node" if it is an "any" Node and its real type has
+  // been given.
+  void MaybePopulateChildrenOfAny(Node* node);
+
+  // Writes the root_ node to ow_ and resets the root_ and current_ pointer to
+  // nullptr.
+  void WriteRoot();
+
+  // Creates a DataPiece containing the default value of the type of the field.
+  static DataPiece CreateDefaultDataPieceForField(
+      const google::protobuf::Field& field);
+
+  // Returns disable_normalize_ and reset it to false.
+  bool GetAndResetDisableNormalize() {
+    return disable_normalize_ ? (disable_normalize_ = false, true) : false;
+  }
+
+  // Adds or replaces the data_ of a primitive child node.
+  void RenderDataPiece(StringPiece name, const DataPiece& data);
+
+  // Type information for all the types used in the descriptor. Used to find
+  // google::protobuf::Type of nested messages/enums.
+  const TypeInfo* typeinfo_;
+  // Whether the TypeInfo object is owned by this class.
+  bool own_typeinfo_;
+  // google::protobuf::Type of the root message type.
+  const google::protobuf::Type& type_;
+  // Holds copies of strings passed to RenderString.
+  vector<string*> string_values_;
+
+  // Whether to disable case normalization of the next node.
+  bool disable_normalize_;
+  // The current Node. Owned by its parents.
+  Node* current_;
+  // The root Node.
+  std::unique_ptr<Node> root_;
+  // The stack to hold the path of Nodes from current_ to root_;
+  std::stack<Node*> stack_;
+
+  ObjectWriter* ow_;
+
+  DISALLOW_COPY_AND_ASSIGN(DefaultValueObjectWriter);
+};
+
+}  // namespace converter
+}  // namespace util
+}  // namespace proto2
+
+#endif  // NET_PROTO2_UTIL_CONVERTER_INTERNAL_DEFAULT_VALUE_OBJECTWRITER_H_
diff --git a/src/google/protobuf/util/field_comparator_test.cc b/src/google/protobuf/util/field_comparator_test.cc
index 845839ac..748c7d11 100644
--- a/src/google/protobuf/util/field_comparator_test.cc
+++ b/src/google/protobuf/util/field_comparator_test.cc
@@ -34,8 +34,8 @@
 
 #include <google/protobuf/unittest.pb.h>
 #include <google/protobuf/descriptor.h>
-#include <google/protobuf/stubs/mathutil.h>
 #include <gtest/gtest.h>
+#include <google/protobuf/stubs/mathutil.h>
 
 namespace google {
 namespace protobuf {
diff --git a/src/google/protobuf/util/field_mask_util.cc b/src/google/protobuf/util/field_mask_util.cc
index 82034bd4..29ca9c1e 100644
--- a/src/google/protobuf/util/field_mask_util.cc
+++ b/src/google/protobuf/util/field_mask_util.cc
@@ -43,7 +43,7 @@ string FieldMaskUtil::ToString(const FieldMask& mask) {
   return Join(mask.paths(), ",");
 }
 
-void FieldMaskUtil::FromString(const string& str, FieldMask* out) {
+void FieldMaskUtil::FromString(StringPiece str, FieldMask* out) {
   out->Clear();
   vector<string> paths = Split(str, ",");
   for (int i = 0; i < paths.size(); ++i) {
@@ -53,7 +53,7 @@ void FieldMaskUtil::FromString(const string& str, FieldMask* out) {
 }
 
 bool FieldMaskUtil::InternalIsValidPath(const Descriptor* descriptor,
-                                        const string& path) {
+                                        StringPiece path) {
   vector<string> parts = Split(path, ".");
   for (int i = 0; i < parts.size(); ++i) {
     const string& field_name = parts[i];
@@ -386,15 +386,15 @@ void FieldMaskUtil::Intersect(const FieldMask& mask1, const FieldMask& mask2,
   intersection.MergeToFieldMask(out);
 }
 
-bool FieldMaskUtil::IsPathInFieldMask(const string& path,
-                                      const FieldMask& mask) {
+bool FieldMaskUtil::IsPathInFieldMask(StringPiece path, const FieldMask& mask) {
   for (int i = 0; i < mask.paths_size(); ++i) {
     const string& mask_path = mask.paths(i);
     if (path == mask_path) {
       return true;
     } else if (mask_path.length() < path.length()) {
       // Also check whether mask.paths(i) is a prefix of path.
-      if (path.compare(0, mask_path.length() + 1, mask_path + ".") == 0) {
+      if (path.substr(0, mask_path.length() + 1).compare(mask_path + ".") ==
+          0) {
         return true;
       }
     }
diff --git a/src/google/protobuf/util/field_mask_util.h b/src/google/protobuf/util/field_mask_util.h
index c99c34f8..92f69893 100644
--- a/src/google/protobuf/util/field_mask_util.h
+++ b/src/google/protobuf/util/field_mask_util.h
@@ -35,6 +35,7 @@
 
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/field_mask.pb.h>
+#include <google/protobuf/stubs/stringpiece.h>
 
 namespace google {
 namespace protobuf {
@@ -47,11 +48,11 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
   // Converts FieldMask to/from string, formatted according to proto3 JSON
   // spec for FieldMask (e.g., "foo,bar,baz.quz").
   static string ToString(const FieldMask& mask);
-  static void FromString(const string& str, FieldMask* out);
+  static void FromString(StringPiece str, FieldMask* out);
 
   // Checks whether the given path is valid for type T.
   template <typename T>
-  static bool IsValidPath(const string& path) {
+  static bool IsValidPath(StringPiece path) {
     return InternalIsValidPath(T::descriptor(), path);
   }
 
@@ -67,7 +68,7 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
   // Adds a path to FieldMask after checking whether the given path is valid.
   // This method check-fails if the path is not a valid path for type T.
   template <typename T>
-  static void AddPathToFieldMask(const string& path, FieldMask* mask) {
+  static void AddPathToFieldMask(StringPiece path, FieldMask* mask) {
     GOOGLE_CHECK(IsValidPath<T>(path));
     mask->add_paths(path);
   }
@@ -96,7 +97,7 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
 
   // Returns true if path is covered by the given FieldMask. Note that path
   // "foo.bar" covers all paths like "foo.bar.baz", "foo.bar.quz.x", etc.
-  static bool IsPathInFieldMask(const string& path, const FieldMask& mask);
+  static bool IsPathInFieldMask(StringPiece path, const FieldMask& mask);
 
   class MergeOptions;
   // Merges fields specified in a FieldMask into another message.
@@ -105,7 +106,7 @@ class LIBPROTOBUF_EXPORT FieldMaskUtil {
 
  private:
   static bool InternalIsValidPath(const Descriptor* descriptor,
-                                  const string& path);
+                                  StringPiece path);
 
   static void InternalGetFieldMaskForAllFields(const Descriptor* descriptor,
                                                FieldMask* out);
diff --git a/src/google/protobuf/util/internal/default_value_objectwriter.h b/src/google/protobuf/util/internal/default_value_objectwriter.h
index d4547601..bcb526e8 100644
--- a/src/google/protobuf/util/internal/default_value_objectwriter.h
+++ b/src/google/protobuf/util/internal/default_value_objectwriter.h
@@ -110,7 +110,7 @@ class LIBPROTOBUF_EXPORT DefaultValueObjectWriter : public ObjectWriter {
 
   // "Node" represents a node in the tree that holds the input of
   // DefaultValueObjectWriter.
-  class Node {
+  class LIBPROTOBUF_EXPORT Node {
    public:
     Node(const string& name, const google::protobuf::Type* type, NodeKind kind,
          const DataPiece& data, bool is_placeholder);
diff --git a/src/google/protobuf/util/internal/json_objectwriter.cc b/src/google/protobuf/util/internal/json_objectwriter.cc
index f81e3306..94d2ab7a 100644
--- a/src/google/protobuf/util/internal/json_objectwriter.cc
+++ b/src/google/protobuf/util/internal/json_objectwriter.cc
@@ -37,8 +37,8 @@
 #include <google/protobuf/stubs/common.h>
 #include <google/protobuf/util/internal/utility.h>
 #include <google/protobuf/util/internal/json_escaping.h>
-#include <google/protobuf/stubs/mathlimits.h>
 #include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/stubs/mathlimits.h>
 
 namespace google {
 namespace protobuf {
@@ -116,7 +116,7 @@ JsonObjectWriter* JsonObjectWriter::RenderUint64(StringPiece name,
 
 JsonObjectWriter* JsonObjectWriter::RenderDouble(StringPiece name,
                                                  double value) {
-  if (google::protobuf::MathLimits<double>::IsFinite(value)) {
+  if (MathLimits<double>::IsFinite(value)) {
     return RenderSimple(name, SimpleDtoa(value));
   }
 
@@ -126,7 +126,7 @@ JsonObjectWriter* JsonObjectWriter::RenderDouble(StringPiece name,
 
 JsonObjectWriter* JsonObjectWriter::RenderFloat(StringPiece name,
                                                 float value) {
-  if (google::protobuf::MathLimits<float>::IsFinite(value)) {
+  if (MathLimits<float>::IsFinite(value)) {
     return RenderSimple(name, SimpleFtoa(value));
   }
 
diff --git a/src/google/protobuf/util/internal/protostream_objectsource.cc b/src/google/protobuf/util/internal/protostream_objectsource.cc
index 996e1f8c..aebf19a1 100644
--- a/src/google/protobuf/util/internal/protostream_objectsource.cc
+++ b/src/google/protobuf/util/internal/protostream_objectsource.cc
@@ -47,7 +47,6 @@
 #include <google/protobuf/util/internal/utility.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/map_util.h>
-#include <google/protobuf/stubs/once.h>
 #include <google/protobuf/stubs/status_macros.h>
 
 
@@ -140,6 +139,7 @@ Status ProtoStreamObjectSource::WriteMessage(const google::protobuf::Type& type,
                                              const uint32 end_tag,
                                              bool include_start_and_end,
                                              ObjectWriter* ow) const {
+
   const TypeRenderer* type_renderer = FindTypeRenderer(type.name());
   if (type_renderer != NULL) {
     return (*type_renderer)(this, type, name, ow);
@@ -332,10 +332,9 @@ Status ProtoStreamObjectSource::RenderDuration(
   if (seconds < 0) {
     if (nanos > 0) {
       return Status(util::error::INTERNAL,
-                    StrCat(
-                        "Duration nanos is non-negative, but seconds is "
-                        "negative for field: ",
-                        field_name));
+                    StrCat("Duration nanos is non-negative, but seconds is "
+                           "negative for field: ",
+                           field_name));
     }
     sign = "-";
     seconds = -seconds;
@@ -648,6 +647,7 @@ Status ProtoStreamObjectSource::RenderFieldMask(
   return Status::OK;
 }
 
+
 hash_map<string, ProtoStreamObjectSource::TypeRenderer>*
     ProtoStreamObjectSource::renderers_ = NULL;
 GOOGLE_PROTOBUF_DECLARE_ONCE(source_renderers_init_);
@@ -670,13 +670,16 @@ void ProtoStreamObjectSource::InitRendererMap() {
       &ProtoStreamObjectSource::RenderInt32;
   (*renderers_)["google.protobuf.UInt32Value"] =
       &ProtoStreamObjectSource::RenderUInt32;
-  (*renderers_)["google.protobuf.BoolValue"] = &ProtoStreamObjectSource::RenderBool;
+  (*renderers_)["google.protobuf.BoolValue"] =
+      &ProtoStreamObjectSource::RenderBool;
   (*renderers_)["google.protobuf.StringValue"] =
       &ProtoStreamObjectSource::RenderString;
   (*renderers_)["google.protobuf.BytesValue"] =
       &ProtoStreamObjectSource::RenderBytes;
-  (*renderers_)["google.protobuf.Any"] = &ProtoStreamObjectSource::RenderAny;
-  (*renderers_)["google.protobuf.Struct"] = &ProtoStreamObjectSource::RenderStruct;
+  (*renderers_)["google.protobuf.Any"] =
+      &ProtoStreamObjectSource::RenderAny;
+  (*renderers_)["google.protobuf.Struct"] =
+      &ProtoStreamObjectSource::RenderStruct;
   (*renderers_)["google.protobuf.Value"] =
       &ProtoStreamObjectSource::RenderStructValue;
   (*renderers_)["google.protobuf.ListValue"] =
@@ -835,6 +838,7 @@ Status ProtoStreamObjectSource::RenderField(
                       StrCat("Invalid configuration. Could not find the type: ",
                              field->type_url()));
       }
+
       RETURN_IF_ERROR(WriteMessage(*type, field_name, 0, true, ow));
       if (!stream_->ConsumedEntireMessage()) {
         return Status(util::error::INVALID_ARGUMENT,
@@ -988,7 +992,7 @@ std::pair<int64, int32> ProtoStreamObjectSource::ReadSecondsAndNanos(
   uint32 nanos = 0;
   uint32 tag = 0;
   int64 signed_seconds = 0;
-  int64 signed_nanos = 0;
+  int32 signed_nanos = 0;
 
   for (tag = stream_->ReadTag(); tag != 0; tag = stream_->ReadTag()) {
     const google::protobuf::Field* field = FindAndVerifyField(type, tag);
diff --git a/src/google/protobuf/util/internal/protostream_objectsource.h b/src/google/protobuf/util/internal/protostream_objectsource.h
index f52383a1..3cd37aa1 100644
--- a/src/google/protobuf/util/internal/protostream_objectsource.h
+++ b/src/google/protobuf/util/internal/protostream_objectsource.h
@@ -188,8 +188,7 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectSource : public ObjectSource {
 
   // Helper to render google.protobuf.Struct's ListValue fields to ObjectWriter.
   static util::Status RenderStructListValue(
-      const ProtoStreamObjectSource* os,
-      const google::protobuf::Type& type,
+      const ProtoStreamObjectSource* os, const google::protobuf::Type& type,
       StringPiece name, ObjectWriter* ow);
 
   // Render the "Any" type.
@@ -211,6 +210,7 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectSource : public ObjectSource {
   util::Status RenderField(const google::protobuf::Field* field,
                              StringPiece field_name, ObjectWriter* ow) const;
 
+
   // Reads field value according to Field spec in 'field' and returns the read
   // value as string. This only works for primitive datatypes (no message
   // types).
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter.cc b/src/google/protobuf/util/internal/protostream_objectwriter.cc
index a935ac39..bd245999 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter.cc
+++ b/src/google/protobuf/util/internal/protostream_objectwriter.cc
@@ -33,13 +33,13 @@
 #include <functional>
 #include <stack>
 
+#include <google/protobuf/stubs/once.h>
 #include <google/protobuf/stubs/time.h>
 #include <google/protobuf/wire_format_lite.h>
 #include <google/protobuf/util/internal/field_mask_utility.h>
 #include <google/protobuf/util/internal/object_location_tracker.h>
 #include <google/protobuf/util/internal/constants.h>
 #include <google/protobuf/util/internal/utility.h>
-#include <google/protobuf/stubs/once.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/map_util.h>
 #include <google/protobuf/stubs/statusor.h>
@@ -397,8 +397,8 @@ void ProtoStreamObjectWriter::AnyWriter::RenderDataPiece(
     const TypeRenderer* type_renderer =
         FindTypeRenderer(GetFullTypeWithUrl(ow_->master_type_.name()));
     if (type_renderer) {
-      // TODO(rikka): Don't just ignore the util::Status object!
-      (*type_renderer)(ow_.get(), value);
+      Status status = (*type_renderer)(ow_.get(), value);
+      if (!status.ok()) ow_->InvalidValue("Any", status.error_message());
     } else {
       ow_->RenderDataPiece(name, value);
     }
@@ -600,6 +600,11 @@ void ProtoStreamObjectWriter::ProtoElement::TakeOneofIndex(int32 index) {
   InsertIfNotPresent(&oneof_indices_, index);
 }
 
+bool ProtoStreamObjectWriter::ProtoElement::InsertMapKeyIfNotPresent(
+    StringPiece map_key) {
+  return InsertIfNotPresent(&map_keys_, map_key);
+}
+
 inline void ProtoStreamObjectWriter::InvalidName(StringPiece unknown_name,
                                                  StringPiece message) {
   listener_->InvalidName(location(), ToSnakeCase(unknown_name), message);
@@ -643,6 +648,11 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartObject(
     return this;
   } else if (element_ != NULL &&
              (element_->IsMap() || element_->IsStructMap())) {
+    if (!ValidMapKey(name)) {
+      ++invalid_depth_;
+      return this;
+    }
+
     field = StartMapEntry(name);
     if (element_->IsStructMapEntry()) {
       // If the top element is a map entry, this means we are starting another
@@ -698,7 +708,7 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartObject(
     element_.reset(
         new ProtoElement(element_.release(), field, *type, ProtoElement::MAP));
   } else {
-    WriteTag(*field);
+      WriteTag(*field);
     element_.reset(new ProtoElement(element_.release(), field, *type,
                                     ProtoElement::MESSAGE));
   }
@@ -863,6 +873,7 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::EndObject() {
   // struct.
   SkipElements();
 
+
   // If ending the root element,
   // then serialize the full message with calculated sizes.
   if (element_ == NULL) {
@@ -914,6 +925,11 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartList(StringPiece name) {
   // Check if we need to start a map. This can heppen when there is either a map
   // or a struct type within a list.
   if (element_->IsMap() || element_->IsStructMap()) {
+    if (!ValidMapKey(name)) {
+      ++invalid_depth_;
+      return this;
+    }
+
     field = StartMapEntry(name);
     if (field == NULL) return this;
 
@@ -969,7 +985,7 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::StartList(StringPiece name) {
                                       ProtoElement::MESSAGE));
       InvalidValue("Map", "Cannot bind a list to map.");
       ++invalid_depth_;
-      element_->pop();
+      element_.reset(element_->pop());
       return this;
     }
 
@@ -1188,6 +1204,7 @@ ProtoStreamObjectWriter* ProtoStreamObjectWriter::RenderDataPiece(
     type_url = GetFullTypeWithUrl(master_type_.name());
   } else {
     if (element_->IsMap() || element_->IsStructMap()) {
+      if (!ValidMapKey(name)) return this;
       is_map_entry = true;
       field = StartMapEntry(name);
     } else {
@@ -1462,6 +1479,19 @@ bool ProtoStreamObjectWriter::ValidOneof(const google::protobuf::Field& field,
   return true;
 }
 
+bool ProtoStreamObjectWriter::ValidMapKey(StringPiece unnormalized_name) {
+  if (element_ == NULL) return true;
+
+  if (!element_->InsertMapKeyIfNotPresent(unnormalized_name)) {
+    InvalidName(
+        unnormalized_name,
+        StrCat("Repeated map key: '", unnormalized_name, "' is already set."));
+    return false;
+  }
+
+  return true;
+}
+
 const google::protobuf::Field* ProtoStreamObjectWriter::BeginNamed(
     StringPiece name, bool is_list) {
   if (invalid_depth_ > 0) {
@@ -1614,6 +1644,7 @@ void ProtoStreamObjectWriter::WriteTag(const google::protobuf::Field& field) {
   stream_->WriteTag(WireFormatLite::MakeTag(field.number(), wire_type));
 }
 
+
 }  // namespace converter
 }  // namespace util
 }  // namespace protobuf
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter.h b/src/google/protobuf/util/internal/protostream_objectwriter.h
index 8f49120b..19f747fe 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter.h
+++ b/src/google/protobuf/util/internal/protostream_objectwriter.h
@@ -259,6 +259,13 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
     // generate an error.
     void TakeOneofIndex(int32 index);
 
+    // Inserts map key into hash set if and only if the key did NOT already
+    // exist in hash set.
+    // The hash set (map_keys_) is ONLY used to keep track of map keys.
+    // Return true if insert successfully; returns false if the map key was
+    // already present.
+    bool InsertMapKeyIfNotPresent(StringPiece map_key);
+
    private:
     // Used for access to variables of the enclosing instance of
     // ProtoStreamObjectWriter.
@@ -296,6 +303,10 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
     // incoming messages so no more than one oneof is set.
     hash_set<int32> oneof_indices_;
 
+    // Set of map keys already seen for the type_. Used to validate incoming
+    // messages so no map key appears more than once.
+    hash_set<StringPiece> map_keys_;
+
     GOOGLE_DISALLOW_IMPLICIT_CONSTRUCTORS(ProtoElement);
   };
 
@@ -378,6 +389,7 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
   // Helper method to write proto tags based on the given field.
   void WriteTag(const google::protobuf::Field& field);
 
+
   // Helper function to render primitive data types in DataPiece.
   void RenderSimpleDataPiece(const google::protobuf::Field& field,
                              const google::protobuf::Type& type,
@@ -424,6 +436,14 @@ class LIBPROTOBUF_EXPORT ProtoStreamObjectWriter : public StructuredObjectWriter
   bool ValidOneof(const google::protobuf::Field& field,
                   StringPiece unnormalized_name);
 
+  // Returns true if the map key for type_ is not duplicated key.
+  // If map key is duplicated key, this function returns false.
+  // Note that caller should make sure that the current proto element (element_)
+  // is of element type MAP or STRUCT_MAP.
+  // It also calls the appropriate error callback and unnormalzied_name is used
+  // for error string.
+  bool ValidMapKey(StringPiece unnormalized_name);
+
   // Variables for describing the structure of the input tree:
   // master_type_: descriptor for the whole protobuf message.
   // typeinfo_ : the TypeInfo object to lookup types.
diff --git a/src/google/protobuf/util/internal/protostream_objectwriter_test.cc b/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
index 96e5ccfb..941fa71a 100644
--- a/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
+++ b/src/google/protobuf/util/internal/protostream_objectwriter_test.cc
@@ -45,6 +45,7 @@
 #include <google/protobuf/util/internal/testdata/field_mask.pb.h>
 #include <google/protobuf/util/internal/type_info_test_helper.h>
 #include <google/protobuf/util/internal/constants.h>
+#include <google/protobuf/util/message_differencer.h>
 #include <google/protobuf/stubs/bytestream.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/util/internal/testdata/anys.pb.h>
@@ -139,7 +140,9 @@ class BaseProtoStreamObjectWriterTest
     google::protobuf::scoped_ptr<Message> message(expected.New());
     message->ParsePartialFromIstream(&istream);
 
-    EXPECT_EQ(expected.DebugString(), message->DebugString());
+    if (!MessageDifferencer::Equivalent(expected, *message)) {
+      EXPECT_EQ(expected.DebugString(), message->DebugString());
+    }
   }
 
   void CheckOutput(const Message& expected) { CheckOutput(expected, -1); }
@@ -851,15 +854,19 @@ class ProtoStreamObjectWriterTimestampDurationTest
   }
 };
 
+INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
+                        ProtoStreamObjectWriterTimestampDurationTest,
+                        ::testing::Values(
+                            testing::USE_TYPE_RESOLVER));
+
 TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError1) {
   TimestampDuration timestamp;
 
   EXPECT_CALL(
       listener_,
-      InvalidValue(
-          _, StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
-          StringPiece("Field 'ts', Illegal timestamp format; timestamps "
-                      "must end with 'Z'")));
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: ")));
 
   ow_->StartObject("")->RenderString("ts", "")->EndObject();
   CheckOutput(timestamp);
@@ -870,10 +877,9 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError2) {
 
   EXPECT_CALL(
       listener_,
-      InvalidValue(
-          _, StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
-          StringPiece(
-              "Field 'ts', Invalid time format: Failed to parse input")));
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: Z")));
 
   ow_->StartObject("")->RenderString("ts", "Z")->EndObject();
   CheckOutput(timestamp);
@@ -884,10 +890,10 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError3) {
 
   EXPECT_CALL(
       listener_,
-      InvalidValue(
-          _, StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
-          StringPiece("Field 'ts', Invalid time format, failed to parse nano "
-                      "seconds")));
+      InvalidValue(_,
+                   StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
+                   StringPiece("Field 'ts', Invalid time format: "
+                               "1970-01-01T00:00:00.ABZ")));
 
   ow_->StartObject("")
       ->RenderString("ts", "1970-01-01T00:00:00.ABZ")
@@ -902,7 +908,8 @@ TEST_P(ProtoStreamObjectWriterTimestampDurationTest, InvalidTimestampError4) {
       listener_,
       InvalidValue(_,
                    StringPiece("type.googleapis.com/google.protobuf.Timestamp"),
-                   StringPiece("Field 'ts', Timestamp value exceeds limits")));
+                   StringPiece("Field 'ts', Invalid time format: "
+                               "-8032-10-18T00:00:00.000Z")));
 
   ow_->StartObject("")
       ->RenderString("ts", "-8032-10-18T00:00:00.000Z")
@@ -1008,6 +1015,11 @@ class ProtoStreamObjectWriterStructTest
   }
 };
 
+INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
+                        ProtoStreamObjectWriterStructTest,
+                        ::testing::Values(
+                            testing::USE_TYPE_RESOLVER));
+
 // TODO(skarvaje): Write tests for failure cases.
 TEST_P(ProtoStreamObjectWriterStructTest, StructRenderSuccess) {
   StructType struct_type;
@@ -1046,12 +1058,62 @@ TEST_P(ProtoStreamObjectWriterStructTest, StructInvalidInputFailure) {
   CheckOutput(struct_type);
 }
 
+TEST_P(ProtoStreamObjectWriterStructTest, SimpleRepeatedStructMapKeyTest) {
+  EXPECT_CALL(
+      listener_,
+      InvalidName(_, StringPiece("k1"),
+                  StringPiece("Repeated map key: 'k1' is already set.")));
+  ow_->StartObject("")
+      ->StartObject("object")
+      ->RenderString("k1", "v1")
+      ->RenderString("k1", "v2")
+      ->EndObject()
+      ->EndObject();
+}
+
+TEST_P(ProtoStreamObjectWriterStructTest, RepeatedStructMapListKeyTest) {
+  EXPECT_CALL(
+      listener_,
+      InvalidName(_, StringPiece("k1"),
+                  StringPiece("Repeated map key: 'k1' is already set.")));
+  ow_->StartObject("")
+      ->StartObject("object")
+      ->RenderString("k1", "v1")
+      ->StartList("k1")
+      ->RenderString("", "v2")
+      ->EndList()
+      ->EndObject()
+      ->EndObject();
+}
+
+TEST_P(ProtoStreamObjectWriterStructTest, RepeatedStructMapObjectKeyTest) {
+  EXPECT_CALL(
+      listener_,
+      InvalidName(_, StringPiece("k1"),
+                  StringPiece("Repeated map key: 'k1' is already set.")));
+  ow_->StartObject("")
+      ->StartObject("object")
+      ->StartObject("k1")
+      ->RenderString("sub_k1", "v1")
+      ->EndObject()
+      ->StartObject("k1")
+      ->RenderString("sub_k2", "v2")
+      ->EndObject()
+      ->EndObject()
+      ->EndObject();
+}
+
 class ProtoStreamObjectWriterMapTest : public BaseProtoStreamObjectWriterTest {
  protected:
   ProtoStreamObjectWriterMapTest()
       : BaseProtoStreamObjectWriterTest(MapIn::descriptor()) {}
 };
 
+INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
+                        ProtoStreamObjectWriterMapTest,
+                        ::testing::Values(
+                            testing::USE_TYPE_RESOLVER));
+
 TEST_P(ProtoStreamObjectWriterMapTest, MapShouldNotAcceptList) {
   MapIn mm;
   EXPECT_CALL(listener_,
@@ -1066,17 +1128,37 @@ TEST_P(ProtoStreamObjectWriterMapTest, MapShouldNotAcceptList) {
   CheckOutput(mm);
 }
 
+TEST_P(ProtoStreamObjectWriterMapTest, RepeatedMapKeyTest) {
+  EXPECT_CALL(
+      listener_,
+      InvalidName(_, StringPiece("k1"),
+                  StringPiece("Repeated map key: 'k1' is already set.")));
+  ow_->StartObject("")
+      ->RenderString("other", "test")
+      ->StartObject("map_input")
+      ->RenderString("k1", "v1")
+      ->RenderString("k1", "v2")
+      ->EndObject()
+      ->EndObject();
+}
+
 class ProtoStreamObjectWriterAnyTest : public BaseProtoStreamObjectWriterTest {
  protected:
   ProtoStreamObjectWriterAnyTest() {
     vector<const Descriptor*> descriptors;
     descriptors.push_back(AnyOut::descriptor());
     descriptors.push_back(google::protobuf::DoubleValue::descriptor());
+    descriptors.push_back(google::protobuf::Timestamp::descriptor());
     descriptors.push_back(google::protobuf::Any::descriptor());
     ResetTypeInfo(descriptors);
   }
 };
 
+INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
+                        ProtoStreamObjectWriterAnyTest,
+                        ::testing::Values(
+                            testing::USE_TYPE_RESOLVER));
+
 TEST_P(ProtoStreamObjectWriterAnyTest, AnyRenderSuccess) {
   AnyOut any;
   google::protobuf::Any* any_type = any.mutable_any();
@@ -1119,8 +1201,6 @@ TEST_P(ProtoStreamObjectWriterAnyTest, RecursiveAny) {
       ->EndObject()
       ->EndObject()
       ->EndObject();
-
-  CheckOutput(out, 115);
 }
 
 TEST_P(ProtoStreamObjectWriterAnyTest, DoubleRecursiveAny) {
@@ -1155,8 +1235,6 @@ TEST_P(ProtoStreamObjectWriterAnyTest, DoubleRecursiveAny) {
       ->EndObject()
       ->EndObject()
       ->EndObject();
-
-  CheckOutput(out, 159);
 }
 
 TEST_P(ProtoStreamObjectWriterAnyTest, EmptyAnyFromEmptyObject) {
@@ -1263,6 +1341,23 @@ TEST_P(ProtoStreamObjectWriterAnyTest, AnyNullInputFails) {
   CheckOutput(any);
 }
 
+TEST_P(ProtoStreamObjectWriterAnyTest, AnyWellKnownTypeErrorTest) {
+  EXPECT_CALL(listener_, InvalidValue(_, StringPiece("Any"),
+                                      StringPiece("Invalid time format: ")));
+
+  AnyOut any;
+  google::protobuf::Any* any_type = any.mutable_any();
+  any_type->set_type_url("type.googleapis.com/google.protobuf.Timestamp");
+
+  ow_->StartObject("")
+      ->StartObject("any")
+      ->RenderString("@type", "type.googleapis.com/google.protobuf.Timestamp")
+      ->RenderString("value", "")
+      ->EndObject()
+      ->EndObject();
+  CheckOutput(any);
+}
+
 class ProtoStreamObjectWriterFieldMaskTest
     : public BaseProtoStreamObjectWriterTest {
  protected:
@@ -1274,6 +1369,11 @@ class ProtoStreamObjectWriterFieldMaskTest
   }
 };
 
+INSTANTIATE_TEST_CASE_P(DifferentTypeInfoSourceTest,
+                        ProtoStreamObjectWriterFieldMaskTest,
+                        ::testing::Values(
+                            testing::USE_TYPE_RESOLVER));
+
 TEST_P(ProtoStreamObjectWriterFieldMaskTest, SimpleFieldMaskTest) {
   FieldMaskTest expected;
   expected.set_id("1");
@@ -1683,6 +1783,7 @@ TEST_P(ProtoStreamObjectWriterOneOfsTest,
   ow_->RenderString("strData", "blah");
   ow_->RenderInt32("intData", 123);
   ow_->EndObject();
+  ow_->EndObject();
 }
 
 }  // namespace converter
diff --git a/src/google/protobuf/util/internal/utility.cc b/src/google/protobuf/util/internal/utility.cc
index 5d7dcc87..61899c24 100644
--- a/src/google/protobuf/util/internal/utility.cc
+++ b/src/google/protobuf/util/internal/utility.cc
@@ -298,16 +298,21 @@ bool IsMap(const google::protobuf::Field& field,
                                  "google.protobuf.MessageOptions.map_entry", false));
 }
 
+bool IsMessageSetWireFormat(const google::protobuf::Type& type) {
+  return GetBoolOptionOrDefault(
+      type.options(), "google.protobuf.MessageOptions.message_set_wire_format", false);
+}
+
 string DoubleAsString(double value) {
-  if (google::protobuf::MathLimits<double>::IsPosInf(value)) return "Infinity";
-  if (google::protobuf::MathLimits<double>::IsNegInf(value)) return "-Infinity";
-  if (google::protobuf::MathLimits<double>::IsNaN(value)) return "NaN";
+  if (MathLimits<double>::IsPosInf(value)) return "Infinity";
+  if (MathLimits<double>::IsNegInf(value)) return "-Infinity";
+  if (MathLimits<double>::IsNaN(value)) return "NaN";
 
   return SimpleDtoa(value);
 }
 
 string FloatAsString(float value) {
-  if (google::protobuf::MathLimits<float>::IsFinite(value)) return SimpleFtoa(value);
+  if (MathLimits<float>::IsFinite(value)) return SimpleFtoa(value);
   return DoubleAsString(value);
 }
 
@@ -318,7 +323,7 @@ bool SafeStrToFloat(StringPiece str, float *value) {
   }
   *value = static_cast<float>(double_value);
 
-  if (google::protobuf::MathLimits<float>::IsInf(*value)) {
+  if (MathLimits<float>::IsInf(*value)) {
     return false;
   }
   return true;
diff --git a/src/google/protobuf/util/internal/utility.h b/src/google/protobuf/util/internal/utility.h
index 87f7602a..5ba97bd2 100644
--- a/src/google/protobuf/util/internal/utility.h
+++ b/src/google/protobuf/util/internal/utility.h
@@ -138,9 +138,6 @@ const google::protobuf::EnumValue* FindEnumValueByNumberOrNull(
     const google::protobuf::Enum* enum_type, int32 value);
 
 // Converts input to camel-case and returns it.
-// Tests are in wrappers/translator/snake2camel_objectwriter_test.cc
-// TODO(skarvaje): Isolate tests for this function and put them in
-// utility_test.cc
 LIBPROTOBUF_EXPORT string ToCamelCase(const StringPiece input);
 
 // Converts input to snake_case and returns it.
@@ -157,6 +154,9 @@ LIBPROTOBUF_EXPORT bool IsValidBoolString(const string& bool_string);
 LIBPROTOBUF_EXPORT bool IsMap(const google::protobuf::Field& field,
            const google::protobuf::Type& type);
 
+// Returns true if the given type has special MessageSet wire format.
+bool IsMessageSetWireFormat(const google::protobuf::Type& type);
+
 // Infinity/NaN-aware conversion to string.
 LIBPROTOBUF_EXPORT string DoubleAsString(double value);
 LIBPROTOBUF_EXPORT string FloatAsString(float value);
diff --git a/src/google/protobuf/util/json_format_proto3.proto b/src/google/protobuf/util/json_format_proto3.proto
index 7a282868..e8137677 100644
--- a/src/google/protobuf/util/json_format_proto3.proto
+++ b/src/google/protobuf/util/json_format_proto3.proto
@@ -100,6 +100,16 @@ message TestMap {
   map<string, int32> string_map = 6;
 }
 
+message TestNestedMap {
+  map<bool, int32> bool_map = 1;
+  map<int32, int32> int32_map = 2;
+  map<int64, int32> int64_map = 3;
+  map<uint32, int32> uint32_map = 4;
+  map<uint64, int32> uint64_map = 5;
+  map<string, int32> string_map = 6;
+  map<string, TestNestedMap> map_map = 7;
+}
+
 message TestWrapper {
   google.protobuf.BoolValue bool_value = 1;
   google.protobuf.Int32Value int32_value = 2;
diff --git a/src/google/protobuf/util/json_util.cc b/src/google/protobuf/util/json_util.cc
index 6cd40fd5..c3b8d502 100644
--- a/src/google/protobuf/util/json_util.cc
+++ b/src/google/protobuf/util/json_util.cc
@@ -34,7 +34,6 @@
 #include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/zero_copy_stream.h>
 #include <google/protobuf/util/internal/default_value_objectwriter.h>
-#include <google/protobuf/util/internal/snake2camel_objectwriter.h>
 #include <google/protobuf/util/internal/error_listener.h>
 #include <google/protobuf/util/internal/json_objectwriter.h>
 #include <google/protobuf/util/internal/json_stream_parser.h>
@@ -83,13 +82,12 @@ util::Status BinaryToJsonStream(TypeResolver* resolver,
   io::CodedOutputStream out_stream(json_output);
   converter::JsonObjectWriter json_writer(options.add_whitespace ? " " : "",
                                           &out_stream);
-  converter::Snake2CamelObjectWriter snake2camel_writer(&json_writer);
   if (options.always_print_primitive_fields) {
     converter::DefaultValueObjectWriter default_value_writer(
-        resolver, type, &snake2camel_writer);
+        resolver, type, &json_writer);
     return proto_source.WriteTo(&default_value_writer);
   } else {
-    return proto_source.WriteTo(&snake2camel_writer);
+    return proto_source.WriteTo(&json_writer);
   }
 }
 
diff --git a/src/google/protobuf/util/message_differencer.cc b/src/google/protobuf/util/message_differencer.cc
index d709da57..9a268973 100644
--- a/src/google/protobuf/util/message_differencer.cc
+++ b/src/google/protobuf/util/message_differencer.cc
@@ -946,6 +946,18 @@ bool MessageDifferencer::IsIgnored(
   return false;
 }
 
+bool MessageDifferencer::IsUnknownFieldIgnored(
+    const Message& message1, const Message& message2,
+    const SpecificField& field, const vector<SpecificField>& parent_fields) {
+  for (int i = 0; i < ignore_criteria_.size(); ++i) {
+    if (ignore_criteria_[i]->IsUnknownFieldIgnored(message1, message2, field,
+                                                   parent_fields)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 const MessageDifferencer::MapKeyComparator* MessageDifferencer
     ::GetMapKeyComparator(const FieldDescriptor* field) {
   if (!field->is_repeated()) return NULL;
@@ -1127,15 +1139,6 @@ bool MessageDifferencer::CompareUnknownFields(
       continue;
     }
 
-    if (change_type == ADDITION || change_type == DELETION ||
-        change_type == MODIFICATION) {
-      if (reporter_ == NULL) {
-        // We found a difference and we have no reproter.
-        return false;
-      }
-      is_different = true;
-    }
-
     // Build the SpecificField.  This is slightly complicated.
     SpecificField specific_field;
     specific_field.unknown_field_number = focus_field->number();
@@ -1160,6 +1163,25 @@ bool MessageDifferencer::CompareUnknownFields(
       specific_field.new_index = index2 - current_repeated_start2;
     }
 
+    if (IsUnknownFieldIgnored(message1, message2, specific_field,
+                              *parent_field)) {
+      if (reporter_ != NULL) {
+        parent_field->push_back(specific_field);
+        reporter_->ReportUnknownFieldIgnored(message1, message2, *parent_field);
+        parent_field->pop_back();
+      }
+      return true;
+    }
+
+    if (change_type == ADDITION || change_type == DELETION ||
+        change_type == MODIFICATION) {
+      if (reporter_ == NULL) {
+        // We found a difference and we have no reproter.
+        return false;
+      }
+      is_different = true;
+    }
+
     parent_field->push_back(specific_field);
 
     switch (change_type) {
@@ -1625,6 +1647,18 @@ void MessageDifferencer::StreamReporter::ReportIgnored(
   printer_->Print("\n");  // Print for newlines.
 }
 
+void MessageDifferencer::StreamReporter::ReportUnknownFieldIgnored(
+    const Message& message1, const Message& message2,
+    const vector<SpecificField>& field_path) {
+  printer_->Print("ignored: ");
+  PrintPath(field_path, true);
+  if (CheckPathChanged(field_path)) {
+    printer_->Print(" -> ");
+    PrintPath(field_path, false);
+  }
+  printer_->Print("\n");  // Print for newlines.
+}
+
 }  // namespace util
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/util/message_differencer.h b/src/google/protobuf/util/message_differencer.h
index e002a0f3..34c173db 100644
--- a/src/google/protobuf/util/message_differencer.h
+++ b/src/google/protobuf/util/message_differencer.h
@@ -278,6 +278,13 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
         const Message& message2,
         const vector<SpecificField>& field_path) { }
 
+    // Report that an unkown field is ignored. (see comment above).
+    // Note this is a different function since the last SpecificField in field
+    // path has a null field.  This could break existing Reporter.
+    virtual void ReportUnknownFieldIgnored(
+        const Message& message1, const Message& message2,
+        const vector<SpecificField>& field_path) {}
+
    private:
     GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(Reporter);
   };
@@ -317,6 +324,16 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
         const Message& message2,
         const FieldDescriptor* field,
         const vector<SpecificField>& parent_fields) = 0;
+
+    // Returns true if the unknown field should be ignored.
+    // Note: This will be called for unknown fields as well in which case
+    //       field.field will be null.
+    virtual bool IsUnknownFieldIgnored(
+        const Message& message1, const Message& message2,
+        const SpecificField& field,
+        const vector<SpecificField>& parent_fields) {
+      return false;
+    }
   };
 
   // To add a Reporter, construct default here, then use ReportDifferencesTo or
@@ -583,6 +600,10 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
                                const Message& message2,
                                const vector<SpecificField>& field_path);
 
+    virtual void ReportUnknownFieldIgnored(
+        const Message& message1, const Message& message2,
+        const vector<SpecificField>& field_path);
+
    protected:
     // Prints the specified path of fields to the buffer.
     virtual void PrintPath(const vector<SpecificField>& field_path,
@@ -722,6 +743,12 @@ class LIBPROTOBUF_EXPORT MessageDifferencer {
       const FieldDescriptor* field,
       const vector<SpecificField>& parent_fields);
 
+  // Returns true if this unknown field is to be ignored when this
+  // MessageDifferencer compares messages.
+  bool IsUnknownFieldIgnored(const Message& message1, const Message& message2,
+                             const SpecificField& field,
+                             const vector<SpecificField>& parent_fields);
+
   // Returns MapKeyComparator* when this field has been configured to
   // be treated as a map.  If not, returns NULL.
   const MapKeyComparator* GetMapKeyComparator(const FieldDescriptor* field);
diff --git a/src/google/protobuf/util/time_util.h b/src/google/protobuf/util/time_util.h
index 58dbf8e6..1bac0897 100644
--- a/src/google/protobuf/util/time_util.h
+++ b/src/google/protobuf/util/time_util.h
@@ -41,7 +41,6 @@
 #endif
 
 #include <google/protobuf/duration.pb.h>
-#include <google/protobuf/stubs/port.h>
 #include <google/protobuf/timestamp.pb.h>
 
 namespace google {
@@ -243,10 +242,8 @@ inline ostream& operator<<(ostream& out, const Duration& d) {
 // Overloaded operators for Timestamp
 //
 // Assignement operators.
-LIBPROTOBUF_EXPORT
-Timestamp& operator+=(Timestamp& t, const Duration& d);  // NOLINT
-LIBPROTOBUF_EXPORT
-Timestamp& operator-=(Timestamp& t, const Duration& d);  // NOLINT
+LIBPROTOBUF_EXPORT Timestamp& operator+=(Timestamp& t, const Duration& d);  // NOLINT
+LIBPROTOBUF_EXPORT Timestamp& operator-=(Timestamp& t, const Duration& d);  // NOLINT
 // Relational operators.
 inline bool operator<(const Timestamp& t1, const Timestamp& t2) {
   if (t1.seconds() == t2.seconds()) {
diff --git a/src/google/protobuf/util/type_resolver_util.cc b/src/google/protobuf/util/type_resolver_util.cc
index 908634eb..a0996954 100644
--- a/src/google/protobuf/util/type_resolver_util.cc
+++ b/src/google/protobuf/util/type_resolver_util.cc
@@ -34,6 +34,7 @@
 #include <google/protobuf/wrappers.pb.h>
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/descriptor.h>
+#include <google/protobuf/util/internal/utility.h>
 #include <google/protobuf/util/type_resolver.h>
 #include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/status.h>
@@ -53,8 +54,7 @@ using util::Status;
 using util::error::INVALID_ARGUMENT;
 using util::error::NOT_FOUND;
 
-bool SplitTypeUrl(const string& type_url,
-                  string* url_prefix,
+bool SplitTypeUrl(const string& type_url, string* url_prefix,
                   string* message_name) {
   size_t pos = type_url.find_last_of("/");
   if (pos == string::npos) {
@@ -65,60 +65,19 @@ bool SplitTypeUrl(const string& type_url,
   return true;
 }
 
-// This code is originally defined in
-// //google/protobuf/util/converter/utility.h. Copied here due to component
-// dependency.
-// TODO(xiaofeng): Remove this when converter code is in components.
-string ToCamelCase(const StringPiece input) {
-  bool capitalize_next = false;
-  bool was_cap = true;
-  bool is_cap = false;
-  bool first_word = true;
-  string result;
-  result.reserve(input.size());
-
-  for (size_t i = 0; i < input.size(); ++i, was_cap = is_cap) {
-    is_cap = ascii_isupper(input[i]);
-    if (input[i] == '_') {
-      capitalize_next = true;
-      if (!result.empty()) first_word = false;
-      continue;
-    } else if (first_word) {
-      // Consider when the current character B is capitalized,
-      // first word ends when:
-      // 1) following a lowercase:   "...aB..."
-      // 2) followed by a lowercase: "...ABc..."
-      if (!result.empty() && is_cap &&
-          (!was_cap || (i + 1 < input.size() && ascii_islower(input[i + 1])))) {
-        first_word = false;
-      } else {
-        result.push_back(ascii_tolower(input[i]));
-        continue;
-      }
-    } else if (capitalize_next) {
-      capitalize_next = false;
-      if (ascii_islower(input[i])) {
-        result.push_back(ascii_toupper(input[i]));
-        continue;
-      }
-    }
-    result.push_back(input[i]);
-  }
-  return result;
-}
-
 class DescriptorPoolTypeResolver : public TypeResolver {
  public:
   DescriptorPoolTypeResolver(const string& url_prefix,
                              const DescriptorPool* pool)
-      : url_prefix_(url_prefix), pool_(pool) {
-  }
+      : url_prefix_(url_prefix), pool_(pool) {}
 
   Status ResolveMessageType(const string& type_url, Type* type) {
     string url_prefix, message_name;
     if (!SplitTypeUrl(type_url, &url_prefix, &message_name) ||
         url_prefix != url_prefix_) {
-      return Status(INVALID_ARGUMENT, "Failed to parse type url: " + type_url);
+      return Status(INVALID_ARGUMENT,
+                    StrCat("Invalid type URL, type URLs must be of the form '",
+                           url_prefix_, "/<typename>', got: ", type_url));
     }
     if (url_prefix != url_prefix_) {
       return Status(INVALID_ARGUMENT,
@@ -126,7 +85,8 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     }
     const Descriptor* descriptor = pool_->FindMessageTypeByName(message_name);
     if (descriptor == NULL) {
-      return Status(NOT_FOUND, "Cannot found the type: " + message_name);
+      return Status(NOT_FOUND,
+                    "Invalid type URL, unknown type: " + message_name);
     }
     ConvertDescriptor(descriptor, type);
     return Status();
@@ -136,7 +96,9 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     string url_prefix, type_name;
     if (!SplitTypeUrl(type_url, &url_prefix, &type_name) ||
         url_prefix != url_prefix_) {
-      return Status(INVALID_ARGUMENT, "Failed to parse type url: " + type_url);
+      return Status(INVALID_ARGUMENT,
+                    StrCat("Invalid type URL, type URLs must be of the form '",
+                           url_prefix_, "/<typename>', got: ", type_url));
     }
     if (url_prefix != url_prefix_) {
       return Status(INVALID_ARGUMENT,
@@ -144,7 +106,7 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     }
     const EnumDescriptor* descriptor = pool_->FindEnumTypeByName(type_name);
     if (descriptor == NULL) {
-      return Status(NOT_FOUND, "Cannot found the type: " + type_name);
+      return Status(NOT_FOUND, "Invalid type URL, unknown type: " + type_name);
     }
     ConvertEnumDescriptor(descriptor, enum_type);
     return Status();
@@ -197,7 +159,7 @@ class DescriptorPoolTypeResolver : public TypeResolver {
     }
     field->set_number(descriptor->number());
     field->set_name(descriptor->name());
-    field->set_json_name(ToCamelCase(descriptor->name()));
+    field->set_json_name(converter::ToCamelCase(descriptor->name()));
     if (descriptor->type() == FieldDescriptor::TYPE_MESSAGE) {
       field->set_type_url(GetTypeUrl(descriptor->message_type()));
     } else if (descriptor->type() == FieldDescriptor::TYPE_ENUM) {
@@ -221,8 +183,7 @@ class DescriptorPoolTypeResolver : public TypeResolver {
         descriptor->file()->name());
     for (int i = 0; i < descriptor->value_count(); ++i) {
       const EnumValueDescriptor* value_descriptor = descriptor->value(i);
-      EnumValue* value =
-          enum_type->mutable_enumvalue()->Add();
+      EnumValue* value = enum_type->mutable_enumvalue()->Add();
       value->set_name(value_descriptor->name());
       value->set_number(value_descriptor->number());
 
@@ -245,8 +206,8 @@ class DescriptorPoolTypeResolver : public TypeResolver {
 
 }  // namespace
 
-TypeResolver* NewTypeResolverForDescriptorPool(
-    const string& url_prefix, const DescriptorPool* pool) {
+TypeResolver* NewTypeResolverForDescriptorPool(const string& url_prefix,
+                                               const DescriptorPool* pool) {
   return new DescriptorPoolTypeResolver(url_prefix, pool);
 }