Merge remote-tracking branch 'upstream/master'

88 files changed, 2035 insertions, 2378 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 3553f974..584bcd21 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -156,6 +156,7 @@ nobase_include_HEADERS =                                        \
   google/protobuf/compiler/python/python_generator.h            \
   google/protobuf/compiler/ruby/ruby_generator.h                \
   google/protobuf/compiler/csharp/csharp_generator.h            \
+  google/protobuf/compiler/csharp/csharp_names.h                \
   google/protobuf/util/type_resolver.h                          \
   google/protobuf/util/type_resolver_util.h                     \
   google/protobuf/util/json_util.h                              \
@@ -428,13 +429,13 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/csharp/csharp_enum.h                \
   google/protobuf/compiler/csharp/csharp_enum_field.cc         \
   google/protobuf/compiler/csharp/csharp_enum_field.h          \
-  google/protobuf/compiler/csharp/csharp_extension.cc          \
-  google/protobuf/compiler/csharp/csharp_extension.h           \
   google/protobuf/compiler/csharp/csharp_field_base.cc         \
   google/protobuf/compiler/csharp/csharp_field_base.h          \
   google/protobuf/compiler/csharp/csharp_generator.cc          \
   google/protobuf/compiler/csharp/csharp_helpers.cc            \
   google/protobuf/compiler/csharp/csharp_helpers.h             \
+  google/protobuf/compiler/csharp/csharp_map_field.cc          \
+  google/protobuf/compiler/csharp/csharp_map_field.h           \
   google/protobuf/compiler/csharp/csharp_message.cc            \
   google/protobuf/compiler/csharp/csharp_message.h             \
   google/protobuf/compiler/csharp/csharp_message_field.cc      \
@@ -451,8 +452,8 @@ libprotoc_la_SOURCES =                                         \
   google/protobuf/compiler/csharp/csharp_source_generator_base.h \
   google/protobuf/compiler/csharp/csharp_umbrella_class.cc     \
   google/protobuf/compiler/csharp/csharp_umbrella_class.h      \
-  google/protobuf/compiler/csharp/csharp_writer.cc             \
-  google/protobuf/compiler/csharp/csharp_writer.h
+  google/protobuf/compiler/csharp/csharp_wrapper_field.cc      \
+  google/protobuf/compiler/csharp/csharp_wrapper_field.h
 
 bin_PROGRAMS = protoc
 protoc_LDADD = $(PTHREAD_LIBS) libprotobuf.la libprotoc.la
diff --git a/src/google/protobuf/any.pb.cc b/src/google/protobuf/any.pb.cc
index 2c492b04..c2e58131 100644
--- a/src/google/protobuf/any.pb.cc
+++ b/src/google/protobuf/any.pb.cc
@@ -82,9 +82,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fany_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\031google/protobuf/any.proto\022\017google.prot"
     "obuf\"&\n\003Any\022\020\n\010type_url\030\001 \001(\t\022\r\n\005value\030\002"
-    " \001(\014BC\n\023com.google.protobufB\010AnyProtoP\001\240"
-    "\001\001\242\002\003GPB\252\002\026Google.ProtocolBuffersb\006proto"
-    "3", 161);
+    " \001(\014BK\n\023com.google.protobufB\010AnyProtoP\001\240"
+    "\001\001\242\002\003GPB\252\002\036Google.Protobuf.WellKnownType"
+    "sb\006proto3", 169);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/any.proto", &protobuf_RegisterTypes);
   Any::default_instance_ = new Any();
diff --git a/src/google/protobuf/any.proto b/src/google/protobuf/any.proto
index e1780fe5..d3ad3acc 100644
--- a/src/google/protobuf/any.proto
+++ b/src/google/protobuf/any.proto
@@ -35,7 +35,7 @@ option java_generate_equals_and_hash = true;
 option java_multiple_files = true;
 option java_outer_classname = "AnyProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/api.pb.cc b/src/google/protobuf/api.pb.cc
index 434320dc..0feddb31 100644
--- a/src/google/protobuf/api.pb.cc
+++ b/src/google/protobuf/api.pb.cc
@@ -123,8 +123,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fapi_2eproto() {
     "quest_type_url\030\002 \001(\t\022\031\n\021request_streamin"
     "g\030\003 \001(\010\022\031\n\021response_type_url\030\004 \001(\t\022\032\n\022re"
     "sponse_streaming\030\005 \001(\010\022(\n\007options\030\006 \003(\0132"
-    "\027.google.protobuf.OptionB\'\n\023com.google.p"
-    "rotobufB\010ApiProtoP\001\242\002\003GPBb\006proto3", 513);
+    "\027.google.protobuf.OptionBH\n\023com.google.p"
+    "rotobufB\010ApiProtoP\001\242\002\003GPB\252\002\036Google.Proto"
+    "buf.WellKnownTypesb\006proto3", 546);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/api.proto", &protobuf_RegisterTypes);
   Api::default_instance_ = new Api();
diff --git a/src/google/protobuf/api.proto b/src/google/protobuf/api.proto
index f368c24d..d6c2a8b3 100644
--- a/src/google/protobuf/api.proto
+++ b/src/google/protobuf/api.proto
@@ -37,6 +37,7 @@ import "google/protobuf/type.proto";
 option java_multiple_files = true;
 option java_outer_classname = "ApiProto";
 option java_package = "com.google.protobuf";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/compiler/command_line_interface.cc b/src/google/protobuf/compiler/command_line_interface.cc
index c57cfd3d..e8871861 100644
--- a/src/google/protobuf/compiler/command_line_interface.cc
+++ b/src/google/protobuf/compiler/command_line_interface.cc
@@ -189,7 +189,7 @@ bool TryCreateParentDirectory(const string& prefix, const string& filename) {
 bool GetProtocAbsolutePath(string* path) {
 #ifdef _WIN32
   char buffer[MAX_PATH];
-  int len = GetModuleFileName(NULL, buffer, MAX_PATH);
+  int len = GetModuleFileNameA(NULL, buffer, MAX_PATH);
 #elif __APPLE__
   char buffer[PATH_MAX];
   int len = 0;
diff --git a/src/google/protobuf/compiler/csharp/csharp_enum_field.cc b/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
index 51a95b9f..d38fb1ed 100644
--- a/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_enum_field.cc
@@ -55,36 +55,29 @@ EnumFieldGenerator::~EnumFieldGenerator() {
 
 void EnumFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   printer->Print(variables_,
-                 "object unknown;\n"
-                 "if(input.ReadEnum(ref result.$name$_, out unknown)) {\n");
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(variables_,
-                   "  result.has$property_name$ = true;\n");
-  }
-  printer->Print("} else if(unknown is int) {\n");
-  if (!use_lite_runtime()) {
-    printer->Print(variables_,
-                   "  if (unknownFields == null) {\n"  // First unknown field - create builder now
-                   "    unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);\n"
-                   "  }\n"
-                   "  unknownFields.MergeVarintField($number$, (ulong)(int)unknown);\n");
-  }
-  printer->Print("}\n");
+    "$name$_ = ($type_name$) input.ReadEnum();\n");
 }
 
 void EnumFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(variables_,
-                 "if ($has_property_check$) {\n"
-                 "  output.WriteEnum($number$, field_names[$field_ordinal$], (int) $property_name$, $property_name$);\n"
-                 "}\n");
+    "if ($has_property_check$) {\n"
+    "  output.WriteRawTag($tag_bytes$);\n"
+    "  output.WriteEnum((int) $property_name$);\n"
+    "}\n");
 }
 
 void EnumFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
-      variables_,
-      "if ($has_property_check$) {\n"
-      "  size += pb::CodedOutputStream.ComputeEnumSize($number$, (int) $property_name$);\n"
-      "}\n");
+    variables_,
+    "if ($has_property_check$) {\n"
+      "  size += $tag_size$ + pb::CodedOutputStream.ComputeEnumSize((int) $property_name$);\n"
+    "}\n");
+}
+
+void EnumFieldGenerator::GenerateCodecCode(io::Printer* printer) {
+    printer->Print(
+        variables_,
+        "pb::FieldCodec.ForEnum($tag$, x => (int) x, x => ($type_name$) x)");
 }
 
 EnumOneofFieldGenerator::EnumOneofFieldGenerator(const FieldDescriptor* descriptor,
@@ -96,30 +89,19 @@ EnumOneofFieldGenerator::~EnumOneofFieldGenerator() {
 }
 
 void EnumOneofFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  // TODO(jonskeet): What about if we read the default value?
   printer->Print(
     variables_,
-    "object unknown;\n"
-    "$type_name$ enumValue = $default_value$;\n"
-    "if(input.ReadEnum(ref enumValue, out unknown)) {\n"
-    "  result.$oneof_name$_ = enumValue;\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "} else if(unknown is int) {\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      variables_,
-      "  if (unknownFields == null) {\n"  // First unknown field - create builder now
-      "    unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);\n"
-      "  }\n"
-      "  unknownFields.MergeVarintField($number$, (ulong)(int)unknown);\n");
-  }
-  printer->Print("}\n");
+    "$oneof_name$_ = input.ReadEnum();\n"
+    "$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n");
 }
 
 void EnumOneofFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  output.WriteEnum($number$, field_names[$field_ordinal$], (int) $property_name$, $property_name$);\n"
+    "  output.WriteRawTag($tag_bytes$);\n"
+    "  output.WriteEnum((int) $property_name$);\n"
     "}\n");
 }
 
@@ -127,7 +109,7 @@ void EnumOneofFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  size += pb::CodedOutputStream.ComputeEnumSize($number$, (int) $property_name$);\n"
+    "  size += $tag_size$ + pb::CodedOutputStream.ComputeEnumSize((int) $property_name$);\n"
     "}\n");
 }
 
diff --git a/src/google/protobuf/compiler/csharp/csharp_enum_field.h b/src/google/protobuf/compiler/csharp/csharp_enum_field.h
index e627b7cc..08364157 100644
--- a/src/google/protobuf/compiler/csharp/csharp_enum_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_enum_field.h
@@ -46,6 +46,7 @@ class EnumFieldGenerator : public PrimitiveFieldGenerator {
   EnumFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~EnumFieldGenerator();
 
+  virtual void GenerateCodecCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
diff --git a/src/google/protobuf/compiler/csharp/csharp_extension.cc b/src/google/protobuf/compiler/csharp/csharp_extension.cc
deleted file mode 100644
index 8b665ae4..00000000
--- a/src/google/protobuf/compiler/csharp/csharp_extension.cc
+++ /dev/null
@@ -1,184 +0,0 @@
-// 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.
-
-#include <sstream>
-
-#include <google/protobuf/compiler/code_generator.h>
-#include <google/protobuf/compiler/plugin.h>
-#include <google/protobuf/descriptor.h>
-#include <google/protobuf/descriptor.pb.h>
-#include <google/protobuf/io/printer.h>
-#include <google/protobuf/io/zero_copy_stream.h>
-
-#include <google/protobuf/compiler/csharp/csharp_extension.h>
-#include <google/protobuf/compiler/csharp/csharp_helpers.h>
-#include <google/protobuf/compiler/csharp/csharp_field_base.h>
-
-using google::protobuf::internal::scoped_ptr;
-
-namespace google {
-namespace protobuf {
-namespace compiler {
-namespace csharp {
-
-ExtensionGenerator::ExtensionGenerator(const FieldDescriptor* descriptor)
-    : FieldGeneratorBase(descriptor, 0) {
-  if (descriptor_->extension_scope()) {
-    variables_["scope"] = GetClassName(descriptor_->extension_scope());
-  } else {
-    variables_["scope"] = GetFullUmbrellaClassName(descriptor_->file());
-  }
-  variables_["extends"] = GetClassName(descriptor_->containing_type());
-  variables_["capitalized_type_name"] = capitalized_type_name();
-  variables_["full_name"] = descriptor_->full_name();
-  variables_["access_level"] = class_access_level();
-  variables_["index"] = SimpleItoa(descriptor_->index());
-  variables_["property_name"] = property_name();
-  variables_["type_name"] = type_name();
-  if (use_lite_runtime()) {
-    variables_["generated_extension"] = descriptor_->is_repeated() ?
-      "GeneratedRepeatExtensionLite" : "GeneratedExtensionLite";
-  } else {
-    variables_["generated_extension"] = descriptor_->is_repeated() ?
-      "GeneratedRepeatExtension" : "GeneratedExtension";
-  }
-}
-
-ExtensionGenerator::~ExtensionGenerator() {
-}
-
-void ExtensionGenerator::Generate(io::Printer* printer) {
-  printer->Print(
-    "public const int $constant_name$ = $number$;\n",
-    "constant_name", GetFieldConstantName(descriptor_),
-    "number", SimpleItoa(descriptor_->number()));
-
-  if (use_lite_runtime()) {
-    // TODO(jtattermusch): include the following check
-    //if (Descriptor.MappedType == MappedType.Message && Descriptor.MessageType.Options.MessageSetWireFormat)
-    //{
-    //    throw new ArgumentException(
-    //        "option message_set_wire_format = true; is not supported in Lite runtime extensions.");
-    //}
-
-    printer->Print(
-      variables_,
-      "$access_level$ static pb::$generated_extension$<$extends$, $type_name$> $property_name$;\n");
-  } else if (descriptor_->is_repeated()) {
-    printer->Print(
-      variables_,
-      "$access_level$ static pb::GeneratedExtensionBase<scg::IList<$type_name$>> $property_name$;\n");
-  } else {
-    printer->Print(
-      variables_,
-      "$access_level$ static pb::GeneratedExtensionBase<$type_name$> $property_name$;\n");
-  }
-}
-
-void ExtensionGenerator::GenerateStaticVariableInitializers(io::Printer* printer) {
-  if (use_lite_runtime()) {
-    printer->Print(
-      variables_,
-      "$scope$.$property_name$ = \n");
-    printer->Indent();
-    printer->Print(
-      variables_,
-      "new pb::$generated_extension$<$extends$, $type_name$>(\n");
-    printer->Indent();
-    printer->Print(
-      variables_,
-      "\"$full_name$\",\n"
-      "$extends$.DefaultInstance,\n");
-    if (!descriptor_->is_repeated()) {
-      std::string default_val;
-      if (descriptor_->has_default_value()) {
-        default_val = default_value();
-      } else {
-        default_val = is_nullable_type() ? "null" : ("default(" + type_name() + ")");
-      }
-      printer->Print("$default_val$,\n", "default_val", default_val);
-    }
-    printer->Print(
-      "$message_val$,\n",
-      "message_val",
-      (GetCSharpType(descriptor_->type()) == CSHARPTYPE_MESSAGE) ?
-	  type_name() + ".DefaultInstance" : "null");
-    printer->Print(
-      "$enum_val$,\n",
-      "enum_val",
-      (GetCSharpType(descriptor_->type()) == CSHARPTYPE_ENUM) ?
-	  "new EnumLiteMap<" + type_name() + ">()" : "null");
-    printer->Print(
-      variables_,
-      "$scope$.$property_name$FieldNumber,\n"
-      "pbd::FieldType.$capitalized_type_name$");
-    if (descriptor_->is_repeated()) {
-      printer->Print(
-        ",\n"
-        "$is_packed$",
-        "is_packed", descriptor_->is_packed() ? "true" : "false");
-    }
-    printer->Outdent();
-    printer->Print(");\n");
-    printer->Outdent();
-  }
-  else if (descriptor_->is_repeated())
-  {
-    printer->Print(
-      variables_,
-      "$scope$.$property_name$ = pb::GeneratedRepeatExtension<$type_name$>.CreateInstance($scope$.Descriptor.Extensions[$index$]);\n");
-  }
-  else
-  {
-    printer->Print(
-      variables_,
-      "$scope$.$property_name$ = pb::GeneratedSingleExtension<$type_name$>.CreateInstance($scope$.Descriptor.Extensions[$index$]);\n");
-  }
-}
-
-void ExtensionGenerator::GenerateExtensionRegistrationCode(io::Printer* printer) {
-  printer->Print(
-    variables_,
-    "registry.Add($scope$.$property_name$);\n");
-}
-
-void ExtensionGenerator::WriteHash(io::Printer* printer) {
-}
-
-void ExtensionGenerator::WriteEquals(io::Printer* printer) {
-}
-
-void ExtensionGenerator::WriteToString(io::Printer* printer) {
-}
-
-}  // namespace csharp
-}  // namespace compiler
-}  // namespace protobuf
-}  // namespace google
diff --git a/src/google/protobuf/compiler/csharp/csharp_field_base.cc b/src/google/protobuf/compiler/csharp/csharp_field_base.cc
index 4c6a3d72..7e3bbeef 100644
--- a/src/google/protobuf/compiler/csharp/csharp_field_base.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_field_base.cc
@@ -35,13 +35,16 @@
 #include <google/protobuf/compiler/plugin.h>
 #include <google/protobuf/descriptor.h>
 #include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/io/coded_stream.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/zero_copy_stream.h>
-#include <google/protobuf/stubs/strutil.h>
 #include <google/protobuf/stubs/mathlimits.h>
+#include <google/protobuf/stubs/strutil.h>
+#include <google/protobuf/wire_format.h>
 
 #include <google/protobuf/compiler/csharp/csharp_field_base.h>
 #include <google/protobuf/compiler/csharp/csharp_helpers.h>
+#include <google/protobuf/compiler/csharp/csharp_names.h>
 
 using google::protobuf::internal::scoped_ptr;
 
@@ -52,6 +55,23 @@ namespace csharp {
 
 void FieldGeneratorBase::SetCommonFieldVariables(
     map<string, string>* variables) {
+  // Note: this will be valid even though the tag emitted for packed and unpacked versions of
+  // repeated fields varies by wire format. The wire format is encoded in the bottom 3 bits, which
+  // never effects the tag size.
+  int tag_size = internal::WireFormat::TagSize(descriptor_->number(), descriptor_->type());
+  uint tag = FixedMakeTag(descriptor_);
+  uint8 tag_array[5];
+  io::CodedOutputStream::WriteTagToArray(tag, tag_array);
+  string tag_bytes = SimpleItoa(tag_array[0]);
+  for (int i = 1; i < tag_size; i++) {
+    tag_bytes += ", " + SimpleItoa(tag_array[i]);
+  }
+
+  (*variables)["access_level"] = class_access_level();
+  (*variables)["tag"] = SimpleItoa(tag);
+  (*variables)["tag_size"] = SimpleItoa(tag_size);
+  (*variables)["tag_bytes"] = tag_bytes;
+
   (*variables)["property_name"] = property_name();
   (*variables)["type_name"] = type_name();
   (*variables)["name"] = name();
@@ -65,16 +85,10 @@ void FieldGeneratorBase::SetCommonFieldVariables(
   }
   (*variables)["capitalized_type_name"] = capitalized_type_name();
   (*variables)["number"] = number();
-  (*variables)["field_ordinal"] = field_ordinal();
-  if (SupportFieldPresence(descriptor_->file())) {
-    (*variables)["has_property_check"] = "has" + (*variables)["property_name"];
-    (*variables)["other_has_property_check"] = "other.Has" + (*variables)["property_name"];
-  } else {
-    (*variables)["has_property_check"] =
-      (*variables)["property_name"] + " != " + (*variables)["default_value"];
-    (*variables)["other_has_property_check"] = "other." +
-      (*variables)["property_name"] + " != " + (*variables)["default_value"];
-  }
+  (*variables)["has_property_check"] =
+    (*variables)["property_name"] + " != " + (*variables)["default_value"];
+  (*variables)["other_has_property_check"] = "other." +
+    (*variables)["property_name"] + " != " + (*variables)["default_value"];
 }
 
 void FieldGeneratorBase::SetCommonOneofFieldVariables(
@@ -96,21 +110,20 @@ FieldGeneratorBase::FieldGeneratorBase(const FieldDescriptor* descriptor,
 FieldGeneratorBase::~FieldGeneratorBase() {
 }
 
-void FieldGeneratorBase::AddDeprecatedFlag(io::Printer* printer) {
-  if (descriptor_->options().deprecated())
-  {
-    printer->Print("[global::System.ObsoleteAttribute()]\n");
-  }
+void FieldGeneratorBase::GenerateFreezingCode(io::Printer* printer) {
+  // No-op: only message fields and repeated fields need
+  // special handling for freezing, so default to not generating any code.
 }
 
-void FieldGeneratorBase::AddNullCheck(io::Printer* printer) {
-  AddNullCheck(printer, "value");
+void FieldGeneratorBase::GenerateCodecCode(io::Printer* printer) {
+    // No-op: expect this to be overridden by appropriate types.
+    // Could fail if we get called here though...
 }
 
-void FieldGeneratorBase::AddNullCheck(io::Printer* printer, const std::string& name) {
-  if (is_nullable_type()) {
-    printer->Print("  pb::ThrowHelper.ThrowIfNull($name$, \"$name$\");\n",
-                   "name", name);
+void FieldGeneratorBase::AddDeprecatedFlag(io::Printer* printer) {
+  if (descriptor_->options().deprecated())
+  {
+    printer->Print("[global::System.ObsoleteAttribute()]\n");
   }
 }
 
@@ -135,12 +148,28 @@ std::string FieldGeneratorBase::name() {
 }
 
 std::string FieldGeneratorBase::type_name() {
-  switch (descriptor_->type()) {
+  return type_name(descriptor_);
+}
+
+std::string FieldGeneratorBase::type_name(const FieldDescriptor* descriptor) {
+  switch (descriptor->type()) {
     case FieldDescriptor::TYPE_ENUM:
-      return GetClassName(descriptor_->enum_type());
+      return GetClassName(descriptor->enum_type());
     case FieldDescriptor::TYPE_MESSAGE:
     case FieldDescriptor::TYPE_GROUP:
-      return GetClassName(descriptor_->message_type());
+      if (IsWrapperType(descriptor)) {
+        const FieldDescriptor* wrapped_field = descriptor->message_type()->field(0);
+        string wrapped_field_type_name = type_name(wrapped_field);
+        // String and ByteString go to the same type; other wrapped types go to the
+        // nullable equivalent.
+        if (wrapped_field->type() == FieldDescriptor::TYPE_STRING ||
+            wrapped_field->type() == FieldDescriptor::TYPE_BYTES) {
+          return wrapped_field_type_name;
+        } else {
+          return wrapped_field_type_name + "?";
+        }
+      }
+      return GetClassName(descriptor->message_type());
     case FieldDescriptor::TYPE_DOUBLE:
       return "double";
     case FieldDescriptor::TYPE_FLOAT:
@@ -259,48 +288,33 @@ bool AllPrintableAscii(const std::string& text) {
 }
 
 std::string FieldGeneratorBase::GetStringDefaultValueInternal() {
-  if (!descriptor_->has_default_value()) {
-    return "\"\"";
-  }
-  if (AllPrintableAscii(descriptor_->default_value_string())) {
-    // All chars are ASCII and printable.  In this case we only
-    // need to escape quotes and backslashes.
-    std::string temp = descriptor_->default_value_string();
-    temp = StringReplace(temp, "\\", "\\\\", true);
-    temp = StringReplace(temp, "'", "\\'", true);
-    temp = StringReplace(temp, "\"", "\\\"", true);
-    return "\"" + temp + "\"";
-  }
-  if (use_lite_runtime()) {
-    return "pb::ByteString.FromBase64(\""
-        + StringToBase64(descriptor_->default_value_string())
-        + "\").ToStringUtf8()";
-  }
-  return "(string) " + GetClassName(descriptor_->containing_type())
-      + ".Descriptor.Fields[" + SimpleItoa(descriptor_->index())
-      + "].DefaultValue";
+  // No other default values needed for proto3...
+  return "\"\"";
 }
 
 std::string FieldGeneratorBase::GetBytesDefaultValueInternal() {
-  if (!descriptor_->has_default_value()) {
-    return "pb::ByteString.Empty";
-  }
-  if (use_lite_runtime()) {
-    return "pb::ByteString.FromBase64(\"" + StringToBase64(descriptor_->default_value_string()) + "\")";
-  }
-  return "(pb::ByteString) "+ GetClassName(descriptor_->containing_type()) +
-      ".Descriptor.Fields[" + SimpleItoa(descriptor_->index()) + "].DefaultValue";
+  // No other default values needed for proto3...
+  return "pb::ByteString.Empty";
 }
 
 std::string FieldGeneratorBase::default_value() {
-  switch (descriptor_->type()) {
+    return default_value(descriptor_);
+}
+
+std::string FieldGeneratorBase::default_value(const FieldDescriptor* descriptor) {
+  switch (descriptor->type()) {
     case FieldDescriptor::TYPE_ENUM:
-      return type_name() + "." + descriptor_->default_value_enum()->name();
+      return type_name() + "." + descriptor->default_value_enum()->name();
     case FieldDescriptor::TYPE_MESSAGE:
     case FieldDescriptor::TYPE_GROUP:
-      return type_name() + ".DefaultInstance";
+      if (IsWrapperType(descriptor)) {
+        const FieldDescriptor* wrapped_field = descriptor->message_type()->field(0);
+        return default_value(wrapped_field);
+      } else {
+        return "null";
+      }
     case FieldDescriptor::TYPE_DOUBLE: {
-      double value = descriptor_->default_value_double();
+      double value = descriptor->default_value_double();
       if (value == numeric_limits<double>::infinity()) {
         return "double.PositiveInfinity";
       } else if (value == -numeric_limits<double>::infinity()) {
@@ -311,7 +325,7 @@ std::string FieldGeneratorBase::default_value() {
       return SimpleDtoa(value) + "D";
     }
     case FieldDescriptor::TYPE_FLOAT: {
-      float value = descriptor_->default_value_float();
+      float value = descriptor->default_value_float();
       if (value == numeric_limits<float>::infinity()) {
         return "float.PositiveInfinity";
       } else if (value == -numeric_limits<float>::infinity()) {
@@ -322,17 +336,17 @@ std::string FieldGeneratorBase::default_value() {
       return SimpleFtoa(value) + "F";
     }
     case FieldDescriptor::TYPE_INT64:
-      return SimpleItoa(descriptor_->default_value_int64()) + "L";
+      return SimpleItoa(descriptor->default_value_int64()) + "L";
     case FieldDescriptor::TYPE_UINT64:
-      return SimpleItoa(descriptor_->default_value_uint64()) + "UL";
+      return SimpleItoa(descriptor->default_value_uint64()) + "UL";
     case FieldDescriptor::TYPE_INT32:
-      return SimpleItoa(descriptor_->default_value_int32());
+      return SimpleItoa(descriptor->default_value_int32());
     case FieldDescriptor::TYPE_FIXED64:
-      return SimpleItoa(descriptor_->default_value_uint64()) + "UL";
+      return SimpleItoa(descriptor->default_value_uint64()) + "UL";
     case FieldDescriptor::TYPE_FIXED32:
-      return SimpleItoa(descriptor_->default_value_uint32());
+      return SimpleItoa(descriptor->default_value_uint32());
     case FieldDescriptor::TYPE_BOOL:
-      if (descriptor_->default_value_bool()) {
+      if (descriptor->default_value_bool()) {
         return "true";
       } else {
         return "false";
@@ -342,15 +356,15 @@ std::string FieldGeneratorBase::default_value() {
     case FieldDescriptor::TYPE_BYTES:
       return GetBytesDefaultValueInternal();
     case FieldDescriptor::TYPE_UINT32:
-      return SimpleItoa(descriptor_->default_value_uint32());
+      return SimpleItoa(descriptor->default_value_uint32());
     case FieldDescriptor::TYPE_SFIXED32:
-      return SimpleItoa(descriptor_->default_value_int32());
+      return SimpleItoa(descriptor->default_value_int32());
     case FieldDescriptor::TYPE_SFIXED64:
-      return SimpleItoa(descriptor_->default_value_int64()) + "L";
+      return SimpleItoa(descriptor->default_value_int64()) + "L";
     case FieldDescriptor::TYPE_SINT32:
-      return SimpleItoa(descriptor_->default_value_int32());
+      return SimpleItoa(descriptor->default_value_int32());
     case FieldDescriptor::TYPE_SINT64:
-      return SimpleItoa(descriptor_->default_value_int64()) + "L";
+      return SimpleItoa(descriptor->default_value_int64()) + "L";
     default:
       GOOGLE_LOG(FATAL)<< "Unknown field type.";
       return "";
@@ -361,11 +375,6 @@ std::string FieldGeneratorBase::number() {
   return SimpleItoa(descriptor_->number());
 }
 
-std::string FieldGeneratorBase::message_or_group() {
-  return
-      (descriptor_->type() == FieldDescriptor::TYPE_GROUP) ? "Group" : "Message";
-}
-
 std::string FieldGeneratorBase::capitalized_type_name() {
   switch (descriptor_->type()) {
     case FieldDescriptor::TYPE_ENUM:
@@ -410,10 +419,6 @@ std::string FieldGeneratorBase::capitalized_type_name() {
   }
 }
 
-std::string FieldGeneratorBase::field_ordinal() {
-  return SimpleItoa(fieldOrdinal_);
-}
-
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/csharp/csharp_field_base.h b/src/google/protobuf/compiler/csharp/csharp_field_base.h
index b1570587..d83543bd 100644
--- a/src/google/protobuf/compiler/csharp/csharp_field_base.h
+++ b/src/google/protobuf/compiler/csharp/csharp_field_base.h
@@ -42,23 +42,23 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class FieldGeneratorBase : public SourceGeneratorBase {
  public:
   FieldGeneratorBase(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~FieldGeneratorBase();
 
+  virtual void GenerateCloningCode(io::Printer* printer) = 0;
+  virtual void GenerateFreezingCode(io::Printer* printer);
+  virtual void GenerateCodecCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer) = 0;
-  virtual void GenerateBuilderMembers(io::Printer* printer) = 0;
   virtual void GenerateMergingCode(io::Printer* printer) = 0;
-  virtual void GenerateBuildingCode(io::Printer* printer) = 0;
   virtual void GenerateParsingCode(io::Printer* printer) = 0;
   virtual void GenerateSerializationCode(io::Printer* printer) = 0;
   virtual void GenerateSerializedSizeCode(io::Printer* printer) = 0;
 
   virtual void WriteHash(io::Printer* printer) = 0;
   virtual void WriteEquals(io::Printer* printer) = 0;
+  // Currently unused, as we use reflection to generate JSON
   virtual void WriteToString(io::Printer* printer) = 0;
 
  protected:
@@ -78,13 +78,13 @@ class FieldGeneratorBase : public SourceGeneratorBase {
   std::string property_name();
   std::string name();
   std::string type_name();
+  std::string type_name(const FieldDescriptor* descriptor);
   bool has_default_value();
   bool is_nullable_type();
   std::string default_value();
+  std::string default_value(const FieldDescriptor* descriptor);
   std::string number();
-  std::string message_or_group();
   std::string capitalized_type_name();
-  std::string field_ordinal();
 
  private:
   void SetCommonFieldVariables(map<string, string>* variables);
diff --git a/src/google/protobuf/compiler/csharp/csharp_generator.cc b/src/google/protobuf/compiler/csharp/csharp_generator.cc
index 2a416fac..e0a6c83a 100644
--- a/src/google/protobuf/compiler/csharp/csharp_generator.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_generator.cc
@@ -50,7 +50,7 @@ namespace csharp {
 
 std::string GetOutputFile(const google::protobuf::FileDescriptor* file, const std::string file_extension)
 {
-  return GetFileUmbrellaClassname(file) + file_extension;
+  return GetUmbrellaClassUnqualifiedName(file) + file_extension;
 }
 
 void GenerateFile(const google::protobuf::FileDescriptor* file,
@@ -68,6 +68,12 @@ bool Generator::Generate(
   vector<pair<string, string> > options;
   ParseGeneratorParameter(parameter, &options);
 
+  // We only support proto3 - but we make an exception for descriptor.proto.
+  if (file->syntax() != FileDescriptor::SYNTAX_PROTO3 && !IsDescriptorProto(file)) {
+    *error = "C# code generation only supports proto3 syntax";
+    return false;
+  }
+
   std::string file_extension = ".cs";
   for (int i = 0; i < options.size(); i++) {
     if (options[i].first == "file_extension") {
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.cc b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
index 76e2c850..46f4fc33 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
@@ -46,11 +46,13 @@
 
 #include <google/protobuf/compiler/csharp/csharp_field_base.h>
 #include <google/protobuf/compiler/csharp/csharp_enum_field.h>
+#include <google/protobuf/compiler/csharp/csharp_map_field.h>
 #include <google/protobuf/compiler/csharp/csharp_message_field.h>
 #include <google/protobuf/compiler/csharp/csharp_primitive_field.h>
 #include <google/protobuf/compiler/csharp/csharp_repeated_enum_field.h>
 #include <google/protobuf/compiler/csharp/csharp_repeated_message_field.h>
 #include <google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h>
+#include <google/protobuf/compiler/csharp/csharp_wrapper_field.h>
 
 namespace google {
 namespace protobuf {
@@ -112,24 +114,21 @@ std::string GetFileNamespace(const FileDescriptor* descriptor) {
   if (descriptor->options().has_csharp_namespace()) {
     return descriptor->options().csharp_namespace();
   }
-  return descriptor->package();
+  return UnderscoresToCamelCase(descriptor->package(), true, true);
 }
 
-std::string GetUmbrellaClassNameInternal(const std::string& proto_file) {
+std::string GetUmbrellaClassUnqualifiedName(const FileDescriptor* descriptor) {
+  // umbrella_classname can no longer be set using message option.
+  std::string proto_file = descriptor->name();
   int lastslash = proto_file.find_last_of("/");
   std::string base = proto_file.substr(lastslash + 1);
   return UnderscoresToPascalCase(StripDotProto(base));
 }
 
-std::string GetFileUmbrellaClassname(const FileDescriptor* descriptor) {
-  // umbrella_classname can no longer be set using message option.
-  return GetUmbrellaClassNameInternal(descriptor->name());
-}
-
-std::string GetFileUmbrellaNamespace(const FileDescriptor* descriptor) {
+std::string GetUmbrellaClassNestedNamespace(const FileDescriptor* descriptor) {
   // TODO(jtattermusch): reintroduce csharp_umbrella_namespace option
   bool collision = false;
-  std::string umbrella_classname = GetFileUmbrellaClassname(descriptor);
+  std::string umbrella_classname = GetUmbrellaClassUnqualifiedName(descriptor);
   for(int i = 0; i < descriptor->message_type_count(); i++) {
     if (descriptor->message_type(i)->name() == umbrella_classname) {
       collision = true;
@@ -153,7 +152,8 @@ std::string GetFileUmbrellaNamespace(const FileDescriptor* descriptor) {
 
 // TODO(jtattermusch): can we reuse a utility function?
 std::string UnderscoresToCamelCase(const std::string& input,
-                                   bool cap_next_letter) {
+                                   bool cap_next_letter,
+                                   bool preserve_period) {
   string result;
   // Note:  I distrust ctype.h due to locales.
   for (int i = 0; i < input.size(); i++) {
@@ -179,6 +179,9 @@ std::string UnderscoresToCamelCase(const std::string& input,
       cap_next_letter = true;
     } else {
       cap_next_letter = true;
+      if (input[i] == '.' && preserve_period) {
+        result += '.';
+      }
     }
   }
   // Add a trailing "_" if the name should be altered.
@@ -205,30 +208,21 @@ std::string ToCSharpName(const std::string& name, const FileDescriptor* file) {
     // the C# namespace.
     classname = name.substr(file->package().size() + 1);
   }
-  result += StringReplace(classname, ".", ".Types.", false);
+  result += StringReplace(classname, ".", ".Types.", true);
   return "global::" + result;
 }
 
-
-
-std::string GetFullUmbrellaClassName(const FileDescriptor* descriptor) {
+std::string GetUmbrellaClassName(const FileDescriptor* descriptor) {
   std::string result = GetFileNamespace(descriptor);
   if (!result.empty()) {
     result += '.';
   }
-  result += GetQualifiedUmbrellaClassName(descriptor);
-  return "global::" + result;
-}
-
-std::string GetQualifiedUmbrellaClassName(const FileDescriptor* descriptor) {
-  std::string umbrellaNamespace = GetFileUmbrellaNamespace(descriptor);
-  std::string umbrellaClassname = GetFileUmbrellaClassname(descriptor);
-
-  std::string fullName = umbrellaClassname;
+  std::string umbrellaNamespace = GetUmbrellaClassNestedNamespace(descriptor);
   if (!umbrellaNamespace.empty()) {
-    fullName = umbrellaNamespace + "." + umbrellaClassname;
+      result += umbrellaNamespace + ".";
   }
-  return fullName;
+  result += GetUmbrellaClassUnqualifiedName(descriptor);
+  return "global::" + result;
 }
 
 std::string GetClassName(const Descriptor* descriptor) {
@@ -257,7 +251,13 @@ std::string GetFieldConstantName(const FieldDescriptor* field) {
 std::string GetPropertyName(const FieldDescriptor* descriptor) {
   // TODO(jtattermusch): consider introducing csharp_property_name field option
   std::string property_name = UnderscoresToPascalCase(GetFieldName(descriptor));
-  if (property_name == descriptor->containing_type()->name()) {
+  // Avoid either our own type name or reserved names. Note that not all names
+  // are reserved - a field called to_string, write_to etc would still cause a problem.
+  // There are various ways of ending up with naming collisions, but we try to avoid obvious
+  // ones.
+  if (property_name == descriptor->containing_type()->name()
+      || property_name == "Types"
+      || property_name == "Descriptor") {
     property_name += "_";
   }
   return property_name;
@@ -338,84 +338,67 @@ std::string FileDescriptorToBase64(const FileDescriptor* descriptor) {
   return StringToBase64(fdp_bytes);
 }
 
+// TODO(jonskeet): Remove this when internal::WireFormat::MakeTag works
+// properly...
+// Workaround for issue #493
+uint FixedMakeTag(const FieldDescriptor* field) {
+  internal::WireFormatLite::WireType field_type = field->is_packed()
+      ? internal::WireFormatLite::WIRETYPE_LENGTH_DELIMITED
+      : internal::WireFormat::WireTypeForFieldType(field->type());
+
+  return internal::WireFormatLite::MakeTag(field->number(), field_type);
+}
+
 FieldGeneratorBase* CreateFieldGenerator(const FieldDescriptor* descriptor,
                                          int fieldOrdinal) {
   switch (descriptor->type()) {
     case FieldDescriptor::TYPE_GROUP:
     case FieldDescriptor::TYPE_MESSAGE:
       if (descriptor->is_repeated()) {
-        return new RepeatedMessageFieldGenerator(descriptor, fieldOrdinal);
+        if (descriptor->is_map()) {
+          return new MapFieldGenerator(descriptor, fieldOrdinal);
+        } else {
+          return new RepeatedMessageFieldGenerator(descriptor, fieldOrdinal);
+        }
       } else {
-	if (descriptor->containing_oneof()) {
-	  return new MessageOneofFieldGenerator(descriptor, fieldOrdinal);
-	} else {
-	  return new MessageFieldGenerator(descriptor, fieldOrdinal);
-	}
+        if (IsWrapperType(descriptor)) {
+          if (descriptor->containing_oneof()) {
+            return new WrapperOneofFieldGenerator(descriptor, fieldOrdinal);
+          } else {
+            return new WrapperFieldGenerator(descriptor, fieldOrdinal);
+          }
+        } else {
+          if (descriptor->containing_oneof()) {
+            return new MessageOneofFieldGenerator(descriptor, fieldOrdinal);
+          } else {
+            return new MessageFieldGenerator(descriptor, fieldOrdinal);
+          }
+        }
       }
     case FieldDescriptor::TYPE_ENUM:
       if (descriptor->is_repeated()) {
         return new RepeatedEnumFieldGenerator(descriptor, fieldOrdinal);
       } else {
-	if (descriptor->containing_oneof()) {
-	  return new EnumOneofFieldGenerator(descriptor, fieldOrdinal);
-	} else {
-	  return new EnumFieldGenerator(descriptor, fieldOrdinal);
-	}
+        if (descriptor->containing_oneof()) {
+          return new EnumOneofFieldGenerator(descriptor, fieldOrdinal);
+        } else {
+          return new EnumFieldGenerator(descriptor, fieldOrdinal);
+        }
       }
     default:
       if (descriptor->is_repeated()) {
         return new RepeatedPrimitiveFieldGenerator(descriptor, fieldOrdinal);
       } else {
-	if (descriptor->containing_oneof()) {
-	  return new PrimitiveOneofFieldGenerator(descriptor, fieldOrdinal);
-	} else {
-	  return new PrimitiveFieldGenerator(descriptor, fieldOrdinal);
-	}
+        if (descriptor->containing_oneof()) {
+          return new PrimitiveOneofFieldGenerator(descriptor, fieldOrdinal);
+        } else {
+          return new PrimitiveFieldGenerator(descriptor, fieldOrdinal);
+        }
       }
   }
 }
 
-bool HasRequiredFields(const Descriptor* descriptor, std::set<const Descriptor*>* already_seen) {
-  if (already_seen->find(descriptor) != already_seen->end()) {
-    // The type is already in cache.  This means that either:
-    // a. The type has no required fields.
-    // b. We are in the midst of checking if the type has required fields,
-    //    somewhere up the stack.  In this case, we know that if the type
-    //    has any required fields, they'll be found when we return to it,
-    //    and the whole call to HasRequiredFields() will return true.
-    //    Therefore, we don't have to check if this type has required fields
-    //    here.
-    return false;
-  }
-  already_seen->insert(descriptor);
-
-  // If the type has extensions, an extension with message type could contain
-  // required fields, so we have to be conservative and assume such an
-  // extension exists.
-  if (descriptor->extension_count() > 0) {
-    return true;
-  }
-
-  for (int i = 0; i < descriptor->field_count(); i++) {
-    const FieldDescriptor* field = descriptor->field(i);
-    if (field->is_required()) {
-      return true;
-    }
-    if (GetCSharpType(field->type()) == CSHARPTYPE_MESSAGE) {
-      if (HasRequiredFields(field->message_type(), already_seen)) {
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-bool HasRequiredFields(const Descriptor* descriptor) {
-  std::set<const Descriptor*> already_seen;
-  return HasRequiredFields(descriptor, &already_seen);
-}
-
-}  // namespace java
+}  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.h b/src/google/protobuf/compiler/csharp/csharp_helpers.h
index bc77f43a..1d17af61 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.h
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.h
@@ -69,15 +69,15 @@ CSharpType GetCSharpType(FieldDescriptor::Type type);
 
 std::string StripDotProto(const std::string& proto_file);
 
-std::string GetFileNamespace(const FileDescriptor* descriptor);
-std::string GetFileUmbrellaClassname(const FileDescriptor* descriptor);
-std::string GetFileUmbrellaNamespace(const FileDescriptor* descriptor);
+// Gets unqualified name of the umbrella class
+std::string GetUmbrellaClassUnqualifiedName(const FileDescriptor* descriptor);
 
-std::string GetFullUmbrellaClassName(const FileDescriptor* descriptor);
-
-std::string GetQualifiedUmbrellaClassName(const FileDescriptor* descriptor);
+// Gets name of the nested for umbrella class (just the nested part,
+// not including the GetFileNamespace part).
+std::string GetUmbrellaClassNestedNamespace(const FileDescriptor* descriptor);
 
 std::string GetClassName(const Descriptor* descriptor);
+
 std::string GetClassName(const EnumDescriptor* descriptor);
 
 std::string GetFieldName(const FieldDescriptor* descriptor);
@@ -88,7 +88,11 @@ std::string GetPropertyName(const FieldDescriptor* descriptor);
 
 int GetFixedSize(FieldDescriptor::Type type);
 
-std::string UnderscoresToCamelCase(const std::string& input, bool cap_next_letter);
+std::string UnderscoresToCamelCase(const std::string& input, bool cap_next_letter, bool preserve_period);
+
+inline std::string UnderscoresToCamelCase(const std::string& input, bool cap_next_letter) {
+  return UnderscoresToCamelCase(input, cap_next_letter, false);
+}
 
 std::string UnderscoresToPascalCase(const std::string& input);
 
@@ -97,12 +101,28 @@ std::string StringToBase64(const std::string& input);
 
 std::string FileDescriptorToBase64(const FileDescriptor* descriptor);
 
+uint FixedMakeTag(const FieldDescriptor* descriptor);
+
 FieldGeneratorBase* CreateFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
 
-bool HasRequiredFields(const Descriptor* descriptor);
+// Determines whether the given message is a map entry message, i.e. one implicitly created
+// by protoc due to a map<key, value> field.
+inline bool IsMapEntryMessage(const Descriptor* descriptor) {
+  return descriptor->options().map_entry();
+}
+
+// Determines whether we're generating code for the proto representation of descriptors etc,
+// for use in the runtime. This is the only type which is allowed to use proto2 syntax,
+// and it generates internal classes.
+inline bool IsDescriptorProto(const FileDescriptor* descriptor) {
+  // TODO: Do this better! (Currently this depends on a hack in generate_protos.sh to rename
+  // the file...)
+  return descriptor->name() == "google/protobuf/descriptor_proto_file.proto";
+}
 
-inline bool SupportFieldPresence(const FileDescriptor* file) {
-  return file->syntax() != FileDescriptor::SYNTAX_PROTO3;
+inline bool IsWrapperType(const FieldDescriptor* descriptor) {
+  return descriptor->type() == FieldDescriptor::TYPE_MESSAGE &&
+      descriptor->message_type()->file()->name() == "google/protobuf/wrappers.proto";
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_map_field.cc b/src/google/protobuf/compiler/csharp/csharp_map_field.cc
new file mode 100644
index 00000000..f84ad6f7
--- /dev/null
+++ b/src/google/protobuf/compiler/csharp/csharp_map_field.cc
@@ -0,0 +1,137 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2015 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.
+
+#include <sstream>
+
+#include <google/protobuf/compiler/code_generator.h>
+#include <google/protobuf/compiler/plugin.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/io/printer.h>
+#include <google/protobuf/io/zero_copy_stream.h>
+#include <google/protobuf/stubs/strutil.h>
+
+#include <google/protobuf/compiler/csharp/csharp_helpers.h>
+#include <google/protobuf/compiler/csharp/csharp_map_field.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace csharp {
+
+MapFieldGenerator::MapFieldGenerator(const FieldDescriptor* descriptor,
+                                             int fieldOrdinal)
+    : FieldGeneratorBase(descriptor, fieldOrdinal) {
+}
+
+MapFieldGenerator::~MapFieldGenerator() {
+}
+
+void MapFieldGenerator::GenerateMembers(io::Printer* printer) {   
+  const FieldDescriptor* key_descriptor =
+      descriptor_->message_type()->FindFieldByName("key");
+  const FieldDescriptor* value_descriptor =
+      descriptor_->message_type()->FindFieldByName("value");
+  variables_["key_type_name"] = type_name(key_descriptor);
+  variables_["value_type_name"] = type_name(value_descriptor);
+  variables_["true_for_wrappers"] = IsWrapperType(value_descriptor) ? "true" : "";
+  scoped_ptr<FieldGeneratorBase> key_generator(CreateFieldGenerator(key_descriptor, 1));  
+  scoped_ptr<FieldGeneratorBase> value_generator(CreateFieldGenerator(value_descriptor, 2));
+
+  printer->Print(
+    variables_,
+    "private static readonly pbc::MapField<$key_type_name$, $value_type_name$>.Codec _map_$name$_codec\n"
+    "    = new pbc::MapField<$key_type_name$, $value_type_name$>.Codec(");
+  key_generator->GenerateCodecCode(printer);
+  printer->Print(", ");
+  value_generator->GenerateCodecCode(printer);
+  printer->Print(
+    variables_,
+    ", $tag$);\n"
+    "private readonly pbc::MapField<$key_type_name$, $value_type_name$> $name$_ = new pbc::MapField<$key_type_name$, $value_type_name$>($true_for_wrappers$);\n");
+  AddDeprecatedFlag(printer);
+  printer->Print(
+    variables_,
+    "$access_level$ pbc::MapField<$key_type_name$, $value_type_name$> $property_name$ {\n"
+    "  get { return $name$_; }\n"
+    "}\n");
+}
+
+void MapFieldGenerator::GenerateMergingCode(io::Printer* printer) {
+  printer->Print(
+      variables_,
+      "$name$_.Add(other.$name$_);\n");
+}
+
+void MapFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "$name$_.AddEntriesFrom(input, _map_$name$_codec);\n");
+}
+
+void MapFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "$name$_.WriteTo(output, _map_$name$_codec);\n");
+}
+
+void MapFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "size += $name$_.CalculateSize(_map_$name$_codec);\n");
+}
+
+void MapFieldGenerator::WriteHash(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "hash ^= $property_name$.GetHashCode();\n");
+}
+void MapFieldGenerator::WriteEquals(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if (!$property_name$.Equals(other.$property_name$)) return false;\n");
+}
+
+void MapFieldGenerator::WriteToString(io::Printer* printer) {
+    // TODO: If we ever actually use ToString, we'll need to impleme this...
+}
+
+void MapFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$name$_ = other.$name$_.Clone();\n");
+}
+
+void MapFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
+
+}  // namespace csharp
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/compiler/csharp/csharp_extension.h b/src/google/protobuf/compiler/csharp/csharp_map_field.h
index f251a21c..f33fe1c3 100644
--- a/src/google/protobuf/compiler/csharp/csharp_extension.h
+++ b/src/google/protobuf/compiler/csharp/csharp_map_field.h
@@ -28,8 +28,8 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef GOOGLE_PROTOBUF_COMPILER_CSHARP_EXTENSION_H__
-#define GOOGLE_PROTOBUF_COMPILER_CSHARP_EXTENSION_H__
+#ifndef GOOGLE_PROTOBUF_COMPILER_CSHARP_MAP_FIELD_H__
+#define GOOGLE_PROTOBUF_COMPILER_CSHARP_MAP_FIELD_H__
 
 #include <string>
 
@@ -41,32 +41,25 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class ExtensionGenerator : public FieldGeneratorBase {
+class MapFieldGenerator : public FieldGeneratorBase {
  public:
-  ExtensionGenerator(const FieldDescriptor* descriptor);
-  ~ExtensionGenerator();
+  MapFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
+  ~MapFieldGenerator();
 
-  void GenerateStaticVariableInitializers(io::Printer* printer);
-  void GenerateExtensionRegistrationCode(io::Printer* printer);
-  void Generate(io::Printer* printer);
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateFreezingCode(io::Printer* printer);
+  virtual void GenerateMembers(io::Printer* printer);
+  virtual void GenerateMergingCode(io::Printer* printer);
+  virtual void GenerateParsingCode(io::Printer* printer);
+  virtual void GenerateSerializationCode(io::Printer* printer);
+  virtual void GenerateSerializedSizeCode(io::Printer* printer);
 
   virtual void WriteHash(io::Printer* printer);
   virtual void WriteEquals(io::Printer* printer);
   virtual void WriteToString(io::Printer* printer);
 
-  virtual void GenerateMembers(io::Printer* printer) {};
-  virtual void GenerateBuilderMembers(io::Printer* printer) {};
-  virtual void GenerateMergingCode(io::Printer* printer) {};
-  virtual void GenerateBuildingCode(io::Printer* printer) {};
-  virtual void GenerateParsingCode(io::Printer* printer) {};
-  virtual void GenerateSerializationCode(io::Printer* printer) {};
-  virtual void GenerateSerializedSizeCode(io::Printer* printer) {};
-
  private:
-  std::string scope_;
-  std::string extends_;
-
-  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ExtensionGenerator);
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MapFieldGenerator);
 };
 
 }  // namespace csharp
@@ -74,5 +67,5 @@ class ExtensionGenerator : public FieldGeneratorBase {
 }  // namespace protobuf
 }  // namespace google
 
-#endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_EXTENSION_H__
+#endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_MAP_FIELD_H__
 
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.cc b/src/google/protobuf/compiler/csharp/csharp_message.cc
index 66b87110..6ea568ca 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message.cc
@@ -43,10 +43,10 @@
 #include <google/protobuf/wire_format_lite.h>
 
 #include <google/protobuf/compiler/csharp/csharp_enum.h>
-#include <google/protobuf/compiler/csharp/csharp_extension.h>
-#include <google/protobuf/compiler/csharp/csharp_message.h>
-#include <google/protobuf/compiler/csharp/csharp_helpers.h>
 #include <google/protobuf/compiler/csharp/csharp_field_base.h>
+#include <google/protobuf/compiler/csharp/csharp_helpers.h>
+#include <google/protobuf/compiler/csharp/csharp_message.h>
+#include <google/protobuf/compiler/csharp/csharp_names.h>
 
 using google::protobuf::internal::scoped_ptr;
 
@@ -96,197 +96,88 @@ const std::vector<const FieldDescriptor*>& MessageGenerator::fields_by_number()
   return fields_by_number_;
 }
 
-/// Get an identifier that uniquely identifies this type within the file.
-/// This is used to declare static variables related to this type at the
-/// outermost file scope.
-std::string GetUniqueFileScopeIdentifier(const Descriptor* descriptor) {
-  std::string result = descriptor->full_name();
-  std::replace(result.begin(), result.end(), '.', '_');
-  return "static_" + result;
-}
-
-void MessageGenerator::GenerateStaticVariables(io::Printer* printer) {
-  // Because descriptor.proto (Google.ProtocolBuffers.DescriptorProtos) is
-  // used in the construction of descriptors, we have a tricky bootstrapping
-  // problem.  To help control static initialization order, we make sure all
-  // descriptors and other static data that depends on them are members of
-  // the proto-descriptor class.  This way, they will be initialized in
-  // a deterministic order.
-
-  std::string identifier = GetUniqueFileScopeIdentifier(descriptor_);
-
-  if (!use_lite_runtime()) {
-    // The descriptor for this type.
-    printer->Print(
-        "internal static pbd::MessageDescriptor internal__$identifier$__Descriptor;\n"
-        "internal static pb::FieldAccess.FieldAccessorTable<$full_class_name$, $full_class_name$.Builder> internal__$identifier$__FieldAccessorTable;\n",
-	"identifier", GetUniqueFileScopeIdentifier(descriptor_),
-	"full_class_name", full_class_name());
-  }
-
-  for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    MessageGenerator messageGenerator(descriptor_->nested_type(i));
-    messageGenerator.GenerateStaticVariables(printer);
-  }
-}
-
-void MessageGenerator::GenerateStaticVariableInitializers(io::Printer* printer) {
-  map<string, string> vars;
-  vars["identifier"] = GetUniqueFileScopeIdentifier(descriptor_);
-  vars["index"] = SimpleItoa(descriptor_->index());
-  vars["full_class_name"] = full_class_name();
-  if (descriptor_->containing_type() != NULL) {
-    vars["parent"] = GetUniqueFileScopeIdentifier(
-	descriptor_->containing_type());
-  }
-  if (!use_lite_runtime()) {
-    printer->Print(vars, "internal__$identifier$__Descriptor = ");
-
-    if (!descriptor_->containing_type()) {
-      printer->Print(vars, "Descriptor.MessageTypes[$index$];\n");
-    } else {
-      printer->Print(vars, "internal__$parent$__Descriptor.NestedTypes[$index$];\n");
-    }
-
-    printer->Print(
-      vars,
-      "internal__$identifier$__FieldAccessorTable = \n"
-      "    new pb::FieldAccess.FieldAccessorTable<$full_class_name$, $full_class_name$.Builder>(internal__$identifier$__Descriptor,\n");
-    printer->Print("        new string[] { ");
-    for (int i = 0; i < descriptor_->field_count(); i++) {
-      printer->Print("\"$property_name$\", ",
-                     "property_name", GetPropertyName(descriptor_->field(i)));
-    }
-    for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-      printer->Print("\"$oneof_name$\", ",
-                     "oneof_name",
-                     UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true));
-    }
-    printer->Print("});\n");
-  }
-
-  // Generate static member initializers for all nested types.
-  for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    MessageGenerator messageGenerator(descriptor_->nested_type(i));
-    messageGenerator.GenerateStaticVariableInitializers(printer);
-  }
-
-  for (int i = 0; i < descriptor_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(descriptor_->extension(i));
-    extensionGenerator.GenerateStaticVariableInitializers(printer);
-  }
-}
-
 void MessageGenerator::Generate(io::Printer* printer) {
   map<string, string> vars;
   vars["class_name"] = class_name();
   vars["access_level"] = class_access_level();
-  vars["extendable_or_generated"] = descriptor_->extension_range_count() > 0 ?
-    "Extendable" : "Generated";
-  vars["suffix"] = runtime_suffix();
-  vars["umbrella_class_name"] = GetFullUmbrellaClassName(descriptor_->file());
-  vars["identifier"] = GetUniqueFileScopeIdentifier(descriptor_);
 
   printer->Print(
-      "[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]\n");
+    "[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]\n");
   WriteGeneratedCodeAttributes(printer);
   printer->Print(
     vars,
-    "$access_level$ sealed partial class $class_name$ : pb::$extendable_or_generated$Message$suffix$<$class_name$, $class_name$.Builder> {\n");
+    "$access_level$ sealed partial class $class_name$ : pb::IMessage<$class_name$> {\n");
   printer->Indent();
+
+  // All static fields and properties
   printer->Print(
-    vars,
-    "private $class_name$() { }\n"  // Private ctor.
-    // Must call MakeReadOnly() to make sure all lists are made read-only
-    "private static readonly $class_name$ defaultInstance = new $class_name$().MakeReadOnly();\n");
+      vars,
+      "private static readonly pb::MessageParser<$class_name$> _parser = new pb::MessageParser<$class_name$>(() => new $class_name$());\n"
+      "public static pb::MessageParser<$class_name$> Parser { get { return _parser; } }\n\n");
 
-  if (optimize_speed()) {
-    printer->Print(
-      "private static readonly string[] _$name$FieldNames = "
-      "new string[] { $slash$$field_names$$slash$ };\n",
-      "name", UnderscoresToCamelCase(class_name(), false),
-      "field_names", JoinStrings(field_names(), "\", \""),
-      "slash", field_names().size() > 0 ? "\"" : "");
-    std::vector<std::string> tags;
-    for (int i = 0; i < field_names().size(); i++) {
-      uint32 tag = internal::WireFormat::MakeTag(
-          descriptor_->FindFieldByName(field_names()[i]));
-      tags.push_back(SimpleItoa(tag));
-    }
-    printer->Print(
-      "private static readonly uint[] _$name$FieldTags = new uint[] { $tags$ };\n",
-      "name", UnderscoresToCamelCase(class_name(), false),
-      "tags", JoinStrings(tags, ", "));
+  // Access the message descriptor via the relevant file descriptor or containing message descriptor.
+  if (!descriptor_->containing_type()) {
+    vars["descriptor_accessor"] = GetUmbrellaClassName(descriptor_->file())
+        + ".Descriptor.MessageTypes[" + SimpleItoa(descriptor_->index()) + "]";
+  } else {
+    vars["descriptor_accessor"] = GetClassName(descriptor_->containing_type())
+        + ".Descriptor.NestedTypes[" + SimpleItoa(descriptor_->index()) + "]";
   }
+
   printer->Print(
     vars,
-    "public static $class_name$ DefaultInstance {\n"
-    "  get { return defaultInstance; }\n"
+    "public static pbr::MessageDescriptor Descriptor {\n"
+    "  get { return $descriptor_accessor$; }\n"
     "}\n"
     "\n"
-    "public override $class_name$ DefaultInstanceForType {\n"
-    "  get { return DefaultInstance; }\n"
+    "pbr::MessageDescriptor pb::IMessage.Descriptor {\n"
+    "  get { return Descriptor; }\n"
     "}\n"
-    "\n"
-    "protected override $class_name$ ThisMessage {\n"
-    "  get { return this; }\n"
-    "}\n\n");
+    "\n");
 
-  if (!use_lite_runtime()) {
-    printer->Print(
-      vars,
-      "public static pbd::MessageDescriptor Descriptor {\n"
-      "  get { return $umbrella_class_name$.internal__$identifier$__Descriptor; }\n"
-      "}\n"
-      "\n"
-      "protected override pb::FieldAccess.FieldAccessorTable<$class_name$, $class_name$.Builder> InternalFieldAccessors {\n"
-      "  get { return $umbrella_class_name$.internal__$identifier$__FieldAccessorTable; }\n"
-      "}\n"
-      "\n");
-  }
+  // Parameterless constructor and partial OnConstruction method.
+  printer->Print(
+    vars,
+    "public $class_name$() {\n"
+    "  OnConstruction();\n"
+    "}\n\n"
+    "partial void OnConstruction();\n\n");
 
-  // Extensions don't need to go in an extra nested type
-  for (int i = 0; i < descriptor_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(descriptor_->extension(i));
-    extensionGenerator.Generate(printer);
-  }
+  GenerateCloningCode(printer);
+  GenerateFreezingCode(printer);
 
-  if (descriptor_->enum_type_count() + descriptor_->nested_type_count() > 0) {
-    printer->Print("#region Nested types\n"
-		   "[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]\n");
-    WriteGeneratedCodeAttributes(printer);
-    printer->Print("public static partial class Types {\n");
-    printer->Indent();
-    for (int i = 0; i < descriptor_->enum_type_count(); i++) {
-      EnumGenerator enumGenerator(descriptor_->enum_type(i));
-      enumGenerator.Generate(printer);
-    }
-    for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-      MessageGenerator messageGenerator(descriptor_->nested_type(i));
-      messageGenerator.Generate(printer);
-    }
-    printer->Outdent();
-    printer->Print("}\n"
-                   "#endregion\n"
-                   "\n");
+  // Fields/properties
+  for (int i = 0; i < descriptor_->field_count(); i++) {
+    const FieldDescriptor* fieldDescriptor = descriptor_->field(i);
+
+    // Rats: we lose the debug comment here :(
+    printer->Print(
+      "public const int $field_constant_name$ = $index$;\n",
+      "field_constant_name", GetFieldConstantName(fieldDescriptor),
+      "index", SimpleItoa(fieldDescriptor->number()));
+    scoped_ptr<FieldGeneratorBase> generator(
+        CreateFieldGeneratorInternal(fieldDescriptor));
+    generator->GenerateMembers(printer);
+    printer->Print("\n");
   }
 
-  // oneof
+  // oneof properties
   for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
     vars["name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
     vars["property_name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
+    vars["original_name"] = descriptor_->oneof_decl(i)->name();
     printer->Print(
       vars,
       "private object $name$_;\n"
       "public enum $property_name$OneofCase {\n");
     printer->Indent();
+    printer->Print("None = 0,\n");
     for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
       const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
       printer->Print("$field_property_name$ = $index$,\n",
                      "field_property_name", GetPropertyName(field),
                      "index", SimpleItoa(field->number()));
     }
-    printer->Print("None = 0,\n");
     printer->Outdent();
     printer->Print("}\n");
     printer->Print(
@@ -294,243 +185,192 @@ void MessageGenerator::Generate(io::Printer* printer) {
       "private $property_name$OneofCase $name$Case_ = $property_name$OneofCase.None;\n"
       "public $property_name$OneofCase $property_name$Case {\n"
       "  get { return $name$Case_; }\n"
+      "}\n\n"
+      "public void Clear$property_name$() {\n"
+      "  $name$Case_ = $property_name$OneofCase.None;\n"
+      "  $name$_ = null;\n"
       "}\n\n");
   }
 
-  // Fields
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* fieldDescriptor = descriptor_->field(i);
+  // Standard methods
+  GenerateFrameworkMethods(printer);
+  GenerateMessageSerializationMethods(printer);
+  GenerateMergingMethods(printer);
 
-    // Rats: we lose the debug comment here :(
-    printer->Print(
-      "public const int $field_constant_name$ = $index$;\n",
-      "field_constant_name", GetFieldConstantName(fieldDescriptor),
-      "index", SimpleItoa(fieldDescriptor->number()));
-    scoped_ptr<FieldGeneratorBase> generator(
-        CreateFieldGeneratorInternal(fieldDescriptor));
-    generator->GenerateMembers(printer);
-    printer->Print("\n");
-  }
-
-  if (optimize_speed()) {
-    if (SupportFieldPresence(descriptor_->file())) {
-      GenerateIsInitialized(printer);
+  // Nested messages and enums
+  if (HasNestedGeneratedTypes()) {
+    printer->Print("#region Nested types\n"
+		   "[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]\n");
+    WriteGeneratedCodeAttributes(printer);
+    printer->Print("public static partial class Types {\n");
+    printer->Indent();
+    for (int i = 0; i < descriptor_->enum_type_count(); i++) {
+      EnumGenerator enumGenerator(descriptor_->enum_type(i));
+      enumGenerator.Generate(printer);
     }
-    GenerateMessageSerializationMethods(printer);
-  }
-  if (use_lite_runtime()) {
-    GenerateLiteRuntimeMethods(printer);
+    for (int i = 0; i < descriptor_->nested_type_count(); i++) {
+      // Don't generate nested types for maps...
+      if (!IsMapEntryMessage(descriptor_->nested_type(i))) {
+        MessageGenerator messageGenerator(descriptor_->nested_type(i));
+        messageGenerator.Generate(printer);
+      }
+    }
+    printer->Outdent();
+    printer->Print("}\n"
+                   "#endregion\n"
+                   "\n");
   }
 
-  GenerateParseFromMethods(printer);
-  GenerateBuilder(printer);
-
-  // Force the static initialization code for the file to run, since it may
-  // initialize static variables declared in this class.
-  printer->Print(vars, "static $class_name$() {\n");
-  // We call object.ReferenceEquals() just to make it a valid statement on its own.
-  // Another option would be GetType(), but that causes problems in DescriptorProtoFile,
-  // where the bootstrapping is somewhat recursive - type initializers call
-  // each other, effectively. We temporarily see Descriptor as null.
-  printer->Print(
-    vars,
-    "  object.ReferenceEquals($umbrella_class_name$.Descriptor, null);\n"
-    "}\n");
-
   printer->Outdent();
   printer->Print("}\n");
   printer->Print("\n");
+}
 
+// Helper to work out whether we need to generate a class to hold nested types/enums.
+// Only tricky because we don't want to generate map entry types.
+bool MessageGenerator::HasNestedGeneratedTypes()
+{
+  if (descriptor_->enum_type_count() > 0) {
+    return true;
+  }
+  for (int i = 0; i < descriptor_->nested_type_count(); i++) {
+    if (!IsMapEntryMessage(descriptor_->nested_type(i))) {
+      return true;
+    }
+  }
+  return false;
 }
 
-void MessageGenerator::GenerateLiteRuntimeMethods(io::Printer* printer) {
+void MessageGenerator::GenerateCloningCode(io::Printer* printer) {
   map<string, string> vars;
   vars["class_name"] = class_name();
-
-  bool callbase = descriptor_->extension_range_count() > 0;
-  printer->Print("#region Lite runtime methods\n"
-                 "public override int GetHashCode() {\n");
+    printer->Print(
+    vars,
+    "public $class_name$($class_name$ other) : this() {\n");
   printer->Indent();
-  printer->Print("int hash = GetType().GetHashCode();\n");
+  // Clone non-oneof fields first
   for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* field = descriptor_->field(i);
-    if (field->containing_oneof() == NULL) {
+    if (!descriptor_->field(i)->containing_oneof()) {
       scoped_ptr<FieldGeneratorBase> generator(
-          CreateFieldGeneratorInternal(field));
-      generator->WriteHash(printer);
+        CreateFieldGeneratorInternal(descriptor_->field(i)));
+      generator->GenerateCloningCode(printer);
     }
   }
-  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-    string name = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
-    string property_name = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
-    printer->Print(
-      "if ($name$Case_ != $property_name$OneofCase.None) {\n"
-      "  hash ^= $name$_.GetHashCode();\n"
-      "}\n",
-      "name", UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false),
-      "property_name",
-      UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true));
-  }
-  if (callbase) {
-    printer->Print("hash ^= base.GetHashCode();\n");
+  // Clone just the right field for each oneof
+  for (int i = 0; i < descriptor_->oneof_decl_count(); ++i) {
+    vars["name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
+    vars["property_name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
+    printer->Print(vars, "switch (other.$property_name$Case) {\n");
+    printer->Indent();
+    for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
+      const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
+      scoped_ptr<FieldGeneratorBase> generator(CreateFieldGeneratorInternal(field));
+      vars["field_property_name"] = GetPropertyName(field);
+      printer->Print(
+          vars,
+          "case $property_name$OneofCase.$field_property_name$:\n");
+      printer->Indent();
+      generator->GenerateCloningCode(printer);
+      printer->Print("break;\n");
+      printer->Outdent();
+    }
+    printer->Outdent();
+    printer->Print("}\n\n");
   }
-  printer->Print("return hash;\n");
+
   printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("\n");
+  printer->Print("}\n\n");
 
-  printer->Print("public override bool Equals(object obj) {\n");
-  printer->Indent();
   printer->Print(
     vars,
-    "$class_name$ other = obj as $class_name$;\n"
-    "if (other == null) return false;\n");
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    scoped_ptr<FieldGeneratorBase> generator(
-        CreateFieldGeneratorInternal(descriptor_->field(i)));
-    generator->WriteEquals(printer);
-  }
-  if (callbase) {
-    printer->Print("if (!base.Equals(other)) return false;\n");
-  }
-  printer->Print("return true;\n");
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("\n");
+    "public $class_name$ Clone() {\n"
+    "  return new $class_name$(this);\n"
+    "}\n\n");
+}
 
-  printer->Print(
-    "public override void PrintTo(global::System.IO.TextWriter writer) {\n");
-  printer->Indent();
+void MessageGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
 
-  for (int i = 0; i < fields_by_number().size(); i++) {
-    scoped_ptr<FieldGeneratorBase> generator(
-        CreateFieldGeneratorInternal(fields_by_number()[i]));
-    generator->WriteToString(printer);
-  }
+void MessageGenerator::GenerateFrameworkMethods(io::Printer* printer) {
+    map<string, string> vars;
+    vars["class_name"] = class_name();
 
-  if (callbase) {
-    printer->Print("base.PrintTo(writer);\n");
-  }
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("#endregion\n");
-  printer->Print("\n");
-}
+    // Equality
+    printer->Print(
+        vars,
+        "public override bool Equals(object other) {\n"
+        "  return Equals(other as $class_name$);\n"
+        "}\n\n"
+        "public bool Equals($class_name$ other) {\n"
+        "  if (ReferenceEquals(other, null)) {\n"
+        "    return false;\n"
+        "  }\n"
+        "  if (ReferenceEquals(other, this)) {\n"
+        "    return true;\n"
+        "  }\n");
+    printer->Indent();
+    for (int i = 0; i < descriptor_->field_count(); i++) {
+        scoped_ptr<FieldGeneratorBase> generator(
+            CreateFieldGeneratorInternal(descriptor_->field(i)));
+        generator->WriteEquals(printer);
+    }
+    printer->Outdent();
+    printer->Print(
+        "  return true;\n"
+        "}\n\n");
+
+    // GetHashCode
+    // Start with a non-zero value to easily distinguish between null and "empty" messages.
+    printer->Print(
+        "public override int GetHashCode() {\n"
+        "  int hash = 1;\n");
+    printer->Indent();
+    for (int i = 0; i < descriptor_->field_count(); i++) {
+        scoped_ptr<FieldGeneratorBase> generator(
+            CreateFieldGeneratorInternal(descriptor_->field(i)));
+        generator->WriteHash(printer);
+    }
+    printer->Print("return hash;\n");
+    printer->Outdent();
+    printer->Print("}\n\n");
 
-bool CompareExtensionRangesStart(const Descriptor::ExtensionRange* r1,
-                                 const Descriptor::ExtensionRange* r2) {
-  return r1->start < r2->start;
+    printer->Print(
+        "public override string ToString() {\n"
+        "  return pb::JsonFormatter.Default.Format(this);\n"
+        "}\n\n");
 }
 
 void MessageGenerator::GenerateMessageSerializationMethods(io::Printer* printer) {
-  std::vector<const Descriptor::ExtensionRange*> extension_ranges_sorted;
-  for (int i = 0; i < descriptor_->extension_range_count(); i++) {
-    extension_ranges_sorted.push_back(descriptor_->extension_range(i));
-  }
-  std::sort(extension_ranges_sorted.begin(), extension_ranges_sorted.end(),
-            CompareExtensionRangesStart);
-
   printer->Print(
-      "public override void WriteTo(pb::ICodedOutputStream output) {\n");
+      "public void WriteTo(pb::CodedOutputStream output) {\n");
   printer->Indent();
-  // Make sure we've computed the serialized length, so that packed fields are generated correctly.
-  printer->Print("CalcSerializedSize();\n"
-		 "string[] field_names = _$class_name$FieldNames;\n",
-                 "class_name", UnderscoresToCamelCase(class_name(), false));
-  if (descriptor_->extension_range_count()) {
-    printer->Print(
-      "pb::ExtendableMessage$runtime_suffix$<$class_name$, $class_name$.Builder>.ExtensionWriter extensionWriter = CreateExtensionWriter(this);\n",
-      "class_name", class_name(),
-      "runtime_suffix", runtime_suffix());
-  }
-
-  // Merge the fields and the extension ranges, both sorted by field number.
-  for (int i = 0, j = 0;
-      i < fields_by_number().size() || j < extension_ranges_sorted.size();) {
-    if (i == fields_by_number().size()) {
-      GenerateSerializeOneExtensionRange(printer, extension_ranges_sorted[j++]);
-    } else if (j == extension_ranges_sorted.size()) {
-      GenerateSerializeOneField(printer, fields_by_number()[i++]);
-    } else if (fields_by_number()[i]->number()
-        < extension_ranges_sorted[j]->start) {
-      GenerateSerializeOneField(printer, fields_by_number()[i++]);
-    } else {
-      GenerateSerializeOneExtensionRange(printer, extension_ranges_sorted[j++]);
-    }
-  }
 
-  if (!use_lite_runtime()) {
-    if (descriptor_->options().message_set_wire_format())
-    {
-      printer->Print("UnknownFields.WriteAsMessageSetTo(output);\n");
-    } else {
-      printer->Print("UnknownFields.WriteTo(output);\n");
-    }
+  // Serialize all the fields
+  for (int i = 0; i < fields_by_number().size(); i++) {
+    scoped_ptr<FieldGeneratorBase> generator(
+      CreateFieldGeneratorInternal(fields_by_number()[i]));
+    generator->GenerateSerializationCode(printer);
   }
 
+  // TODO(jonskeet): Memoize size of frozen messages?
   printer->Outdent();
   printer->Print(
     "}\n"
     "\n"
-    "private int memoizedSerializedSize = -1;\n"
-    "public override int SerializedSize {\n");
-  printer->Indent();
-  printer->Print("get {\n");
-  printer->Indent();
-  printer->Print(
-    "int size = memoizedSerializedSize;\n"
-    "if (size != -1) return size;\n"
-    "return CalcSerializedSize();\n");
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("\n");
-
-  printer->Print("private int CalcSerializedSize() {\n");
+    "public int CalculateSize() {\n");
   printer->Indent();
-  printer->Print(
-    "int size = memoizedSerializedSize;\n"
-    "if (size != -1) return size;\n"
-    "\n"
-    "size = 0;\n");
+  printer->Print("int size = 0;\n");
   for (int i = 0; i < descriptor_->field_count(); i++) {
     scoped_ptr<FieldGeneratorBase> generator(
         CreateFieldGeneratorInternal(descriptor_->field(i)));
     generator->GenerateSerializedSizeCode(printer);
   }
-  if (descriptor_->extension_range_count() > 0) {
-    printer->Print("size += ExtensionsSerializedSize;\n");
-  }
-
-  if (!use_lite_runtime()) {
-    if (descriptor_->options().message_set_wire_format()) {
-      printer->Print("size += UnknownFields.SerializedSizeAsMessageSet;\n");
-    } else {
-      printer->Print("size += UnknownFields.SerializedSize;\n");
-    }
-  }
-  printer->Print(
-    "memoizedSerializedSize = size;\n"
-    "return size;\n");
+  printer->Print("return size;\n");
   printer->Outdent();
-  printer->Print("}\n");
-}
-
-void MessageGenerator::GenerateSerializeOneField(
-    io::Printer* printer, const FieldDescriptor* fieldDescriptor) {
-  scoped_ptr<FieldGeneratorBase> generator(
-      CreateFieldGeneratorInternal(fieldDescriptor));
-  generator->GenerateSerializationCode(printer);
-}
-
-void MessageGenerator::GenerateSerializeOneExtensionRange(
-    io::Printer* printer, const Descriptor::ExtensionRange* extensionRange) {
-  printer->Print("extensionWriter.WriteUntil($range_end$, output);\n",
-		 "range_end", SimpleItoa(extensionRange->end));
+  printer->Print("}\n\n");
 }
 
-void MessageGenerator::GenerateParseFromMethods(io::Printer* printer) {
+void MessageGenerator::GenerateMergingMethods(io::Printer* printer) {
   // Note:  These are separate from GenerateMessageSerializationMethods()
   //   because they need to be generated even for messages that are optimized
   //   for code size.
@@ -539,346 +379,69 @@ void MessageGenerator::GenerateParseFromMethods(io::Printer* printer) {
 
   printer->Print(
     vars,
-    "public static $class_name$ ParseFrom(pb::ByteString data) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(pb::ByteString data, pb::ExtensionRegistry extensionRegistry) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(byte[] data) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(data)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(byte[] data, pb::ExtensionRegistry extensionRegistry) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(data, extensionRegistry)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(global::System.IO.Stream input) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseDelimitedFrom(global::System.IO.Stream input) {\n"
-    "  return CreateBuilder().MergeDelimitedFrom(input).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseDelimitedFrom(global::System.IO.Stream input, pb::ExtensionRegistry extensionRegistry) {\n"
-    "  return CreateBuilder().MergeDelimitedFrom(input, extensionRegistry).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(pb::ICodedInputStream input) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(input)).BuildParsed();\n"
-    "}\n"
-    "public static $class_name$ ParseFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {\n"
-    "  return ((Builder) CreateBuilder().MergeFrom(input, extensionRegistry)).BuildParsed();\n"
-    "}\n");
-}
-
-void MessageGenerator::GenerateBuilder(io::Printer* printer) {
-  map<string, string> vars;
-  vars["class_name"] = class_name();
-  vars["access_level"] = class_access_level();
-  vars["extendable_or_generated"] = descriptor_->extension_range_count() > 0 ?
-    "Extendable" : "Generated";
-  vars["suffix"] = runtime_suffix();
-
-  printer->Print(vars, "private $class_name$ MakeReadOnly() {\n");
+    "public void MergeFrom($class_name$ other) {\n");
   printer->Indent();
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    scoped_ptr<FieldGeneratorBase> generator(
-        CreateFieldGeneratorInternal(descriptor_->field(i)));
-    generator->GenerateBuildingCode(printer);
-  }
-  printer->Print("return this;\n");
-  printer->Outdent();
-  printer->Print("}\n\n");
-
   printer->Print(
-    vars,
-    "public static Builder CreateBuilder() { return new Builder(); }\n"
-    "public override Builder ToBuilder() { return CreateBuilder(this); }\n"
-    "public override Builder CreateBuilderForType() { return new Builder(); }\n"
-    "public static Builder CreateBuilder($class_name$ prototype) {\n"
-    "  return new Builder(prototype);\n"
-    "}\n"
-    "\n"
-    "[global::System.Diagnostics.DebuggerNonUserCodeAttribute()]\n");
-  WriteGeneratedCodeAttributes(printer);
-  printer->Print(
-    vars,
-    "$access_level$ sealed partial class Builder : pb::$extendable_or_generated$Builder$suffix$<$class_name$, Builder> {\n");
-  printer->Indent();
-  printer->Print(
-    "protected override Builder ThisBuilder {\n"
-    "  get { return this; }\n"
+    "if (other == null) {\n"
+    "  return;\n"
     "}\n");
-  GenerateCommonBuilderMethods(printer);
-  if (optimize_speed()) {
-    GenerateBuilderParsingMethods(printer);
-  }
+  // Merge non-oneof fields
   for (int i = 0; i < descriptor_->field_count(); i++) {
-    scoped_ptr<FieldGeneratorBase> generator(
-        CreateFieldGeneratorInternal(descriptor_->field(i)));
-    printer->Print("\n");
-    // No field comment :(
-    generator->GenerateBuilderMembers(printer);
-  }
-
-  // oneof
-  for (int i = 0; i < descriptor_->oneof_decl_count(); i++) {
-    printer->Print("\n");
-    string name = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
-    string property_name = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
-    printer->Print(
-      "public $property_name$OneofCase $property_name$Case {\n"
-      "  get { return result.$name$Case_; }\n"
-      "}\n"
-      "public Builder Clear$property_name$() {\n"
-      "  PrepareBuilder();\n"
-      "  result.$name$_ = null;\n"
-      "  result.$name$Case_ = $property_name$OneofCase.None;\n"
-      "  return this;\n"
-      "}\n",
-      "name", UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false),
-      "property_name",
-      UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true));
-  }
-
-  printer->Outdent();
-  printer->Print("}\n");
-}
-
-void MessageGenerator::GenerateCommonBuilderMethods(io::Printer* printer) {
-  map<string, string> vars;
-  vars["class_name"] = class_name();
-  vars["full_class_name"] = full_class_name();
-  vars["suffix"] = runtime_suffix();
-
-  printer->Print(
-    vars,
-    //default constructor
-    "public Builder() {\n"
-    //Durring static initialization of message, DefaultInstance is expected to return null.
-    "  result = DefaultInstance;\n"
-    "  resultIsReadOnly = true;\n"
-    "}\n"
-    //clone constructor
-    "internal Builder($class_name$ cloneFrom) {\n"
-    "  result = cloneFrom;\n"
-    "  resultIsReadOnly = true;\n"
-    "}\n"
-    "\n"
-    "private bool resultIsReadOnly;\n"
-    "private $class_name$ result;\n"
-    "\n"
-    "private $class_name$ PrepareBuilder() {\n"
-    "  if (resultIsReadOnly) {\n"
-    "    $class_name$ original = result;\n"
-    "    result = new $class_name$();\n"
-    "    resultIsReadOnly = false;\n"
-    "    MergeFrom(original);\n"
-    "  }\n"
-    "  return result;\n"
-    "}\n"
-    "\n"
-    "public override bool IsInitialized {\n"
-    "  get { return result.IsInitialized; }\n"
-    "}\n"
-    "\n"
-    "protected override $class_name$ MessageBeingBuilt {\n"
-    "  get { return PrepareBuilder(); }\n"
-    "}\n"
-    "\n");
-  //Not actually expecting that DefaultInstance would ever be null here; however, we will ensure it does not break
-  printer->Print(
-    "public override Builder Clear() {\n"
-    "  result = DefaultInstance;\n"
-    "  resultIsReadOnly = true;\n"
-    "  return this;\n"
-    "}\n"
-    "\n"
-    "public override Builder Clone() {\n"
-    "  if (resultIsReadOnly) {\n"
-    "    return new Builder(result);\n"
-    "  } else {\n"
-    "    return new Builder().MergeFrom(result);\n"
-    "  }\n"
-    "}\n"
-    "\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      vars,
-      "public override pbd::MessageDescriptor DescriptorForType {\n"
-      "  get { return $full_class_name$.Descriptor; }\n"
-      "}\n\n");
+    if (!descriptor_->field(i)->containing_oneof()) {      
+      scoped_ptr<FieldGeneratorBase> generator(
+          CreateFieldGeneratorInternal(descriptor_->field(i)));
+      generator->GenerateMergingCode(printer);
+    }
   }
-  printer->Print(
-    vars,
-    "public override $class_name$ DefaultInstanceForType {\n"
-    "  get { return $full_class_name$.DefaultInstance; }\n"
-    "}\n\n");
-
-  printer->Print(
-    vars,
-    "public override $class_name$ BuildPartial() {\n"
-    "  if (resultIsReadOnly) {\n"
-    "    return result;\n"
-    "  }\n"
-    "  resultIsReadOnly = true;\n"
-    "  return result.MakeReadOnly();\n"
-    "}\n\n");
-
-  if (optimize_speed()) {
-    printer->Print(
-      vars,
-      "public override Builder MergeFrom(pb::IMessage$suffix$ other) {\n"
-      "  if (other is $class_name$) {\n"
-      "    return MergeFrom(($class_name$) other);\n"
-      "  } else {\n"
-      "    base.MergeFrom(other);\n"
-      "    return this;\n"
-      "  }\n"
-      "}\n\n");
-
-    printer->Print(vars,"public override Builder MergeFrom($class_name$ other) {\n");
-    // Optimization:  If other is the default instance, we know none of its
-    // fields are set so we can skip the merge.
+  // Merge oneof fields
+  for (int i = 0; i < descriptor_->oneof_decl_count(); ++i) {
+    vars["name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
+    vars["property_name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
+    printer->Print(vars, "switch (other.$property_name$Case) {\n");
     printer->Indent();
-    printer->Print(
-      vars,
-      "if (other == $full_class_name$.DefaultInstance) return this;\n"
-      "PrepareBuilder();\n");
-    for (int i = 0; i < descriptor_->field_count(); i++) {
-      if (!descriptor_->field(i)->containing_oneof()) {
-	scoped_ptr<FieldGeneratorBase> generator(
-	  CreateFieldGeneratorInternal(descriptor_->field(i)));
-	generator->GenerateMergingCode(printer);
-      }
-     }
-
-    // Merge oneof fields
-    for (int i = 0; i < descriptor_->oneof_decl_count(); ++i) {
-      vars["name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
-      vars["property_name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), true);
-      printer->Print(vars, "switch (other.$property_name$Case) {\n");
-      printer->Indent();
-      for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
-        const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
-	vars["field_property_name"] = GetPropertyName(field);
-	printer->Print(
-          vars,
-          "case $property_name$OneofCase.$field_property_name$: {\n");
-	if (field->type() == FieldDescriptor::TYPE_GROUP ||
-	    field->type() == FieldDescriptor::TYPE_MESSAGE) {
-	  printer->Print(
-            vars,
-            "  Merge$field_property_name$(other.$field_property_name$);\n");
-	} else {
-	  printer->Print(
-            vars,
-            "  Set$field_property_name$(other.$field_property_name$);\n");
-	}
-        printer->Print("  break;\n");
-	printer->Print("}\n");
-      }
-      printer->Print(vars, "case $property_name$OneofCase.None: { break; }\n");
-      printer->Outdent();
-      printer->Print("}\n");
-    }
-
-    // if message type has extensions
-    if (descriptor_->extension_range_count() > 0) {
-      printer->Print("  this.MergeExtensionFields(other);\n");
-    }
-    if (!use_lite_runtime()) {
-      printer->Print("this.MergeUnknownFields(other.UnknownFields);\n");
+    for (int j = 0; j < descriptor_->oneof_decl(i)->field_count(); j++) {
+      const FieldDescriptor* field = descriptor_->oneof_decl(i)->field(j);
+      vars["field_property_name"] = GetPropertyName(field);
+      printer->Print(
+        vars,
+        "case $property_name$OneofCase.$field_property_name$:\n"
+        "  $field_property_name$ = other.$field_property_name$;\n"
+        "  break;\n");
     }
-    printer->Print("return this;\n");
     printer->Outdent();
     printer->Print("}\n\n");
   }
-
-}
-
-void MessageGenerator::GenerateBuilderParsingMethods(io::Printer* printer) {
-  printer->Print(
-    "public override Builder MergeFrom(pb::ICodedInputStream input) {\n"
-    "  return MergeFrom(input, pb::ExtensionRegistry.Empty);\n"
-    "}\n\n");
-
-  printer->Print(
-    "public override Builder MergeFrom(pb::ICodedInputStream input, pb::ExtensionRegistry extensionRegistry) {\n");
+  printer->Outdent();
+  printer->Print("}\n\n");
+  printer->Print("public void MergeFrom(pb::CodedInputStream input) {\n");
   printer->Indent();
-  printer->Print("PrepareBuilder();\n");
-  if (!use_lite_runtime()) {
-    printer->Print("pb::UnknownFieldSet.Builder unknownFields = null;\n");
-  }
   printer->Print(
     "uint tag;\n"
-    "string field_name;\n"
-    "while (input.ReadTag(out tag, out field_name)) {\n");
-  printer->Indent();
-  printer->Print("if(tag == 0 && field_name != null) {\n");
+    "while (input.ReadTag(out tag)) {\n"
+    "  switch(tag) {\n");
   printer->Indent();
-  //if you change from StringComparer.Ordinal, the array sort in FieldNames { get; } must also change
-  printer->Print(
-    "int field_ordinal = global::System.Array.BinarySearch(_$camel_class_name$FieldNames, field_name, global::System.StringComparer.Ordinal);\n"
-    "if(field_ordinal >= 0)\n"
-    "  tag = _$camel_class_name$FieldTags[field_ordinal];\n"
-    "else {\n",
-    "camel_class_name", UnderscoresToCamelCase(class_name(), false));
-  if (!use_lite_runtime()) {
-    printer->Print(
-      "  if (unknownFields == null) {\n"  // First unknown field - create builder now
-      "    unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);\n"
-      "  }\n");
-  }
-  printer->Print(
-    "  ParseUnknownField(input, $prefix$extensionRegistry, tag, field_name);\n",
-    "prefix", use_lite_runtime() ? "" : "unknownFields, ");
-  printer->Print("  continue;\n");
-  printer->Print("}\n");
-  printer->Outdent();
-  printer->Print("}\n");
-
-  printer->Print("switch (tag) {\n");
   printer->Indent();
   printer->Print(
-    "case 0: {\n"  // 0 signals EOF / limit reached
+    "case 0:\n"  // 0 signals EOF / limit reached
     "  throw pb::InvalidProtocolBufferException.InvalidTag();\n"
-    "}\n"
-    "default: {\n"
-    "  if (pb::WireFormat.IsEndGroupTag(tag)) {\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      "    if (unknownFields != null) {\n"
-      "      this.UnknownFields = unknownFields.Build();\n"
-      "    }\n");
-  }
-  printer->Print(
-    "    return this;\n"  // it's an endgroup tag
-    "  }\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      "  if (unknownFields == null) {\n"  // First unknown field - create builder now
-      "    unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);\n"
-      "  }\n");
-  }
-  printer->Print(
-      "  ParseUnknownField(input, $prefix$extensionRegistry, tag, field_name);\n",
-      "prefix", use_lite_runtime() ? "" : "unknownFields, ");
-  printer->Print("  break;\n");
-  printer->Print("}\n");
-
+    "default:\n"
+    "  if (pb::WireFormat.IsEndGroupTag(tag)) {\n"
+    "    return;\n"
+    "  }\n"
+    "  break;\n"); // Note: we're ignoring unknown fields here.
   for (int i = 0; i < fields_by_number().size(); i++) {
     const FieldDescriptor* field = fields_by_number()[i];
     internal::WireFormatLite::WireType wt =
         internal::WireFormat::WireTypeForFieldType(field->type());
     uint32 tag = internal::WireFormatLite::MakeTag(field->number(), wt);
-    if (field->is_repeated()
-        && (wt == internal::WireFormatLite::WIRETYPE_VARINT
-            || wt == internal::WireFormatLite::WIRETYPE_FIXED32
-            || wt == internal::WireFormatLite::WIRETYPE_FIXED64)) {
+    // Handle both packed and unpacked repeated fields with the same Read*Array call;
+    // the two generated cases are the packed and unpacked tags.
+    // TODO(jonskeet): Check that is_packable is equivalent to is_repeated && wt in { VARINT, FIXED32, FIXED64 }.
+    // It looks like it is...
+    if (field->is_packable()) {
       printer->Print(
-        "case $number$:\n",
-        "number",
+        "case $packed_tag$:\n",
+        "packed_tag",
         SimpleItoa(
             internal::WireFormatLite::MakeTag(
                 field->number(),
@@ -894,95 +457,12 @@ void MessageGenerator::GenerateBuilderParsingMethods(io::Printer* printer) {
     printer->Outdent();
     printer->Print("}\n");
   }
-
   printer->Outdent();
-  printer->Print("}\n");
+  printer->Print("}\n"); // switch
   printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      "if (unknownFields != null) {\n"
-      "  this.UnknownFields = unknownFields.Build();\n"
-      "}\n");
-  }
-  printer->Print("return this;\n");
+  printer->Print("}\n"); // while
   printer->Outdent();
-  printer->Print("}\n\n");
-}
-
-void MessageGenerator::GenerateIsInitialized(io::Printer* printer) {
-  printer->Print("public override bool IsInitialized {\n");
-  printer->Indent();
-  printer->Print("get {\n");
-  printer->Indent();
-
-  // Check that all required fields in this message are set.
-  // TODO(kenton):  We can optimize this when we switch to putting all the
-  // "has" fields into a single bitfield.
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    if (descriptor_->field(i)->is_required()) {
-      printer->Print("if (!has$property_name$) return false;\n",
-		     "property_name", GetPropertyName(descriptor_->field(i)));
-    }
-  }
-
-  // Now check that all embedded messages are initialized.
-  for (int i = 0; i < descriptor_->field_count(); i++) {
-    const FieldDescriptor* field = descriptor_->field(i);
-
-      if (field->type() != FieldDescriptor::TYPE_MESSAGE ||
-          !HasRequiredFields(field->message_type()))
-      {
-          continue;
-      }
-      // TODO(jtattermusch): shouldn't we use GetPropertyName here?
-      string propertyName = UnderscoresToPascalCase(GetFieldName(field));
-      if (field->is_repeated())
-      {
-        printer->Print(
-          "foreach ($class_name$ element in $property_name$List) {\n"
-          "  if (!element.IsInitialized) return false;\n"
-          "}\n",
-          "class_name", GetClassName(field->message_type()),
-          "property_name", propertyName);
-      }
-      else if (field->is_optional())
-      {
-        printer->Print(
-          "if (Has$property_name$) {\n"
-          "  if (!$property_name$.IsInitialized) return false;\n"
-          "}\n",
-          "property_name", propertyName);
-      }
-      else
-      {
-        printer->Print(
-          "if (!$property_name$.IsInitialized) return false;\n",
-          "property_name", propertyName);
-      }
-  }
-
-  if (descriptor_->extension_range_count() > 0) {
-    printer->Print("if (!ExtensionsAreInitialized) return false;\n");
-  }
-  printer->Print("return true;\n");
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("\n");
-}
-
-void MessageGenerator::GenerateExtensionRegistrationCode(io::Printer* printer) {
-  for (int i = 0; i < descriptor_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(descriptor_->extension(i));
-    extensionGenerator.GenerateExtensionRegistrationCode(printer);
-  }
-  for (int i = 0; i < descriptor_->nested_type_count(); i++) {
-    MessageGenerator messageGenerator(descriptor_->nested_type(i));
-    messageGenerator.GenerateExtensionRegistrationCode(printer);
-  }
+  printer->Print("}\n\n"); // method
 }
 
 int MessageGenerator::GetFieldOrdinal(const FieldDescriptor* descriptor) {
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.h b/src/google/protobuf/compiler/csharp/csharp_message.h
index ebe58618..f0c49ac9 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.h
+++ b/src/google/protobuf/compiler/csharp/csharp_message.h
@@ -43,7 +43,6 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
 class FieldGeneratorBase;
 
 class MessageGenerator : public SourceGeneratorBase {
@@ -51,9 +50,9 @@ class MessageGenerator : public SourceGeneratorBase {
   MessageGenerator(const Descriptor* descriptor);
   ~MessageGenerator();
 
-  void GenerateStaticVariables(io::Printer* printer);
-  void GenerateStaticVariableInitializers(io::Printer* printer);
-  void GenerateExtensionRegistrationCode(io::Printer* printer);
+  void GenerateCloningCode(io::Printer* printer);
+  void GenerateFreezingCode(io::Printer* printer);
+  void GenerateFrameworkMethods(io::Printer* printer);
   void Generate(io::Printer* printer);
 
  private:
@@ -61,22 +60,15 @@ class MessageGenerator : public SourceGeneratorBase {
   std::vector<std::string> field_names_;
   std::vector<const FieldDescriptor*> fields_by_number_;
 
-  void GenerateLiteRuntimeMethods(io::Printer* printer);
   void GenerateMessageSerializationMethods(io::Printer* printer);
-  void GenerateSerializeOneField(io::Printer* printer,
-                                 const FieldDescriptor* fieldDescriptor);
-  void GenerateSerializeOneExtensionRange(
-      io::Printer* printer, const Descriptor::ExtensionRange* extendsionRange);
-  void GenerateParseFromMethods(io::Printer* printer);
-  void GenerateBuilder(io::Printer* printer);
-  void GenerateCommonBuilderMethods(io::Printer* printer);
-  void GenerateBuilderParsingMethods(io::Printer* printer);
-  void GenerateIsInitialized(io::Printer* printer);
+  void GenerateMergingMethods(io::Printer* printer);
 
   int GetFieldOrdinal(const FieldDescriptor* descriptor);
   FieldGeneratorBase* CreateFieldGeneratorInternal(
       const FieldDescriptor* descriptor);
 
+  bool HasNestedGeneratedTypes();
+
   std::string class_name();
   std::string full_class_name();
 
@@ -95,4 +87,3 @@ class MessageGenerator : public SourceGeneratorBase {
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_MESSAGE_H__
-
diff --git a/src/google/protobuf/compiler/csharp/csharp_message_field.cc b/src/google/protobuf/compiler/csharp/csharp_message_field.cc
index 50eb9df6..4f576cd1 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message_field.cc
@@ -49,8 +49,8 @@ namespace csharp {
 MessageFieldGenerator::MessageFieldGenerator(const FieldDescriptor* descriptor,
                                              int fieldOrdinal)
     : FieldGeneratorBase(descriptor, fieldOrdinal) {
-  variables_["has_property_check"] = "has" + property_name();
-  variables_["message_or_group"] = message_or_group();
+  variables_["has_property_check"] = name() + "_ != null";
+  variables_["has_not_property_check"] = name() + "_ == null";
 }
 
 MessageFieldGenerator::~MessageFieldGenerator() {
@@ -60,125 +60,45 @@ MessageFieldGenerator::~MessageFieldGenerator() {
 void MessageFieldGenerator::GenerateMembers(io::Printer* printer) {
   printer->Print(
     variables_,
-    "private bool has$property_name$;\n"
     "private $type_name$ $name$_;\n");
   AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public bool Has$property_name$ {\n"
-    "  get { return has$property_name$; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return $name$_ ?? $default_value$; }\n"
-    "}\n");
-}
-
-void MessageFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public bool Has$property_name$ {\n"
-    " get { return result.has$property_name$; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return result.$property_name$; }\n"
-    "  set { Set$property_name$(value); }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.has$property_name$ = true;\n"
-    "  result.$name$_ = value;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$.Builder builderForValue) {\n");
-  AddNullCheck(printer, "builderForValue");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.has$property_name$ = true;\n"
-    "  result.$name$_ = builderForValue.Build();\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Merge$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  if (result.has$property_name$ &&\n"
-    "      result.$name$_ != $default_value$) {\n"
-    "      result.$name$_ = $type_name$.CreateBuilder(result.$name$_).MergeFrom(value).BuildPartial();\n"
-    "  } else {\n"
-    "    result.$name$_ = value;\n"
+    "$access_level$ $type_name$ $property_name$ {\n"
+    "  get { return $name$_; }\n"
+    "  set {\n"
+    "    $name$_ = value;\n"
     "  }\n"
-    "  result.has$property_name$ = true;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n"
-    "  result.has$property_name$ = false;\n"
-    "  result.$name$_ = null;\n"
-    "  return this;\n"
     "}\n");
 }
 
 void MessageFieldGenerator::GenerateMergingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (other.Has$property_name$) {\n"
-    "  Merge$property_name$(other.$property_name$);\n"
+    "if (other.$has_property_check$) {\n"
+    "  if ($has_not_property_check$) {\n"
+    "    $name$_ = new $type_name$();\n"
+    "  }\n"
+    "  $property_name$.MergeFrom(other.$property_name$);\n"
     "}\n");
 }
 
-void MessageFieldGenerator::GenerateBuildingCode(io::Printer* printer) {
-  // Nothing to do for singular fields
-}
-
 void MessageFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "$type_name$.Builder subBuilder = $type_name$.CreateBuilder();\n"
-    "if (result.has$property_name$) {\n"
-    "  subBuilder.MergeFrom($property_name$);\n"
-    "}\n");
-
-  if (descriptor_->type() == FieldDescriptor::TYPE_GROUP) {
-    printer->Print(
-      variables_,
-      "input.ReadGroup($number$, subBuilder, extensionRegistry);\n");
-  } else {
-    printer->Print("input.ReadMessage(subBuilder, extensionRegistry);\n");
-  }
-  printer->Print(
-    variables_,
-    "$property_name$ = subBuilder.BuildPartial();\n");
+    "if ($has_not_property_check$) {\n"
+    "  $name$_ = new $type_name$();\n"
+    "}\n"
+    // TODO(jonskeet): Do we really need merging behaviour like this?
+    "input.ReadMessage($name$_);\n"); // No need to support TYPE_GROUP...
 }
 
 void MessageFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  output.Write$message_or_group$($number$, field_names[$field_ordinal$], $property_name$);\n"
+    "  output.WriteRawTag($tag_bytes$);\n"
+    "  output.WriteMessage($property_name$);\n"
     "}\n");
 }
 
@@ -186,19 +106,19 @@ void MessageFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  size += pb::CodedOutputStream.Compute$message_or_group$Size($number$, $property_name$);\n"
+    "  size += $tag_size$ + pb::CodedOutputStream.ComputeMessageSize($property_name$);\n"
     "}\n");
 }
 
 void MessageFieldGenerator::WriteHash(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (has$property_name$) hash ^= $name$_.GetHashCode();\n");
+    "if ($has_property_check$) hash ^= $property_name$.GetHashCode();\n");
 }
 void MessageFieldGenerator::WriteEquals(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (has$property_name$ != other.has$property_name$ || (has$property_name$ && !$name$_.Equals(other.$name$_))) return false;\n");
+    "if (!object.Equals($property_name$, other.$property_name$)) return false;\n");
 }
 void MessageFieldGenerator::WriteToString(io::Printer* printer) {
   variables_["field_name"] = GetFieldName(descriptor_);
@@ -207,6 +127,20 @@ void MessageFieldGenerator::WriteToString(io::Printer* printer) {
     "PrintField(\"$field_name$\", has$property_name$, $name$_, writer);\n");
 }
 
+void MessageFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$property_name$ = other.$has_property_check$ ? other.$property_name$.Clone() : null;\n");
+}
+
+void MessageFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
+
+void MessageFieldGenerator::GenerateCodecCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "pb::FieldCodec.ForMessage($tag$, $type_name$.Parser)");
+}
+
 MessageOneofFieldGenerator::MessageOneofFieldGenerator(const FieldDescriptor* descriptor,
 						       int fieldOrdinal)
     : MessageFieldGenerator(descriptor, fieldOrdinal) {
@@ -218,124 +152,41 @@ MessageOneofFieldGenerator::~MessageOneofFieldGenerator() {
 }
 
 void MessageOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
-  if (SupportFieldPresence(descriptor_->file())) {
-    AddDeprecatedFlag(printer);
-    printer->Print(
-      variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return $has_property_check$; }\n"
-      "}\n");
-  }
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : $default_value$; }\n"
-    "}\n");
-}
-
-void MessageOneofFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  if (SupportFieldPresence(descriptor_->file())) {
-    AddDeprecatedFlag(printer);
-    printer->Print(
-      variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return result.$has_property_check$; }\n"
-      "}\n");
-  }
   AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return result.$has_property_check$ ? ($type_name$) result.$oneof_name$_ : $default_value$; }\n"
-    "  set { Set$property_name$(value); }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "  result.$oneof_name$_ = value;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$.Builder builderForValue) {\n");
-  AddNullCheck(printer, "builderForValue");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "  result.$oneof_name$_ = builderForValue.Build();\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Merge$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  if (result.$has_property_check$ &&\n"
-    "      result.$property_name$ != $default_value$) {\n"
-    "    result.$oneof_name$_ = $type_name$.CreateBuilder(result.$property_name$).MergeFrom(value).BuildPartial();\n"
-    "  } else {\n"
-    "    result.$oneof_name$_ = value;\n"
-    "  }\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  if (result.$has_property_check$) {\n"
-    "    PrepareBuilder();\n"
-    "    result.$oneof_name$Case_ = $oneof_property_name$OneofCase.None;\n"
-    "    result.$oneof_name$_ = null;\n"
+    "$access_level$ $type_name$ $property_name$ {\n"
+    "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : null; }\n"
+    "  set {\n"
+    "    $oneof_name$_ = value;\n"
+    "    $oneof_name$Case_ = value == null ? $oneof_property_name$OneofCase.None : $oneof_property_name$OneofCase.$property_name$;\n"
     "  }\n"
-    "  return this;\n"
     "}\n");
 }
 
 void MessageOneofFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  // TODO(jonskeet): We may be able to do better than this
   printer->Print(
     variables_,
-    "$type_name$.Builder subBuilder = $type_name$.CreateBuilder();\n"
-    "if (result.$has_property_check$) {\n"
+    "$type_name$ subBuilder = new $type_name$();\n"
+    "if ($has_property_check$) {\n"
     "  subBuilder.MergeFrom($property_name$);\n"
-    "}\n");
-
-  if (descriptor_->type() == FieldDescriptor::TYPE_GROUP) {
-    printer->Print(
-      variables_,
-      "input.ReadGroup($number$, subBuilder, extensionRegistry);\n");
-  } else {
-    printer->Print("input.ReadMessage(subBuilder, extensionRegistry);\n");
-  }
-  printer->Print(
-    variables_,
-    "result.$oneof_name$_ = subBuilder.BuildPartial();\n"
-    "result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n");
+    "}\n"
+    "input.ReadMessage(subBuilder);\n" // No support of TYPE_GROUP
+    "$property_name$ = subBuilder;\n");
 }
 
-void MessageOneofFieldGenerator::WriteEquals(io::Printer* printer) {
-  printer->Print(
-    variables_,
-    "if (!$property_name$.Equals(other.$property_name$)) return false;\n");
-}
 void MessageOneofFieldGenerator::WriteToString(io::Printer* printer) {
   printer->Print(
     variables_,
     "PrintField(\"$descriptor_name$\", $has_property_check$, $oneof_name$_, writer);\n");
 }
 
+void MessageOneofFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$property_name$ = other.$property_name$.Clone();\n");
+}
+
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/csharp/csharp_message_field.h b/src/google/protobuf/compiler/csharp/csharp_message_field.h
index d820908c..dc6e4dc5 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_message_field.h
@@ -41,17 +41,16 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class MessageFieldGenerator : public FieldGeneratorBase {
  public:
   MessageFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~MessageFieldGenerator();
 
+  virtual void GenerateCodecCode(io::Printer* printer);
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateFreezingCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
   virtual void GenerateMergingCode(io::Printer* printer);
-  virtual void GenerateBuildingCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
@@ -69,9 +68,8 @@ class MessageOneofFieldGenerator : public MessageFieldGenerator {
   MessageOneofFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~MessageOneofFieldGenerator();
 
+  virtual void GenerateCloningCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
-  virtual void WriteEquals(io::Printer* printer);
   virtual void WriteToString(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
 
diff --git a/src/google/protobuf/compiler/csharp/csharp_writer.h b/src/google/protobuf/compiler/csharp/csharp_names.h
index 26c59b31..ccd2e720 100644
--- a/src/google/protobuf/compiler/csharp/csharp_writer.h
+++ b/src/google/protobuf/compiler/csharp/csharp_names.h
@@ -31,63 +31,52 @@
 // Author: kenton@google.com (Kenton Varda)
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// Provides a mechanism for mapping a descriptor to the
+// fully-qualified name of the corresponding C# class.
 
-#ifndef GOOGLE_PROTOBUF_COMPILER_CSHARP_WRITER_H__
-#define GOOGLE_PROTOBUF_COMPILER_CSHARP_WRITER_H__
+#ifndef GOOGLE_PROTOBUF_COMPILER_CSHARP_NAMES_H__
+#define GOOGLE_PROTOBUF_COMPILER_CSHARP_NAMES_H__
 
 #include <string>
-#include <google/protobuf/descriptor.pb.h>
-#include <google/protobuf/descriptor.h>
-#include <google/protobuf/compiler/code_generator.h>
-#include <google/protobuf/io/printer.h>
 
 namespace google {
 namespace protobuf {
-namespace compiler {
-namespace csharp {
-
-// Simple wrapper around Printer that supports customizable line endings
-// and number-based variables (e.g. $0$).
-class Writer {
- public:
-  Writer(io::Printer* printer);
-  ~Writer();
-
-  void Indent();
-  void Outdent();
-
-  void Write(const char* text);
-
-  void Write(const char* text, const string& value0);
-
-  void Write(const char* text, const string& value0, const string& value1);
-
-  void Write(const char* text, const string& value0, const string& value1,
-             const string& value2);
 
-  void Write(const char* text, const string& value0, const string& value1,
-             const string& value2, const string& value3);
+class Descriptor;
+class EnumDescriptor;
+class FileDescriptor;
+class ServiceDescriptor;
 
-  void WriteLine();
-
-  void WriteLine(const char* text);
-
-  void WriteLine(const char* text, const string& value0);
+namespace compiler {
+namespace csharp {
 
-  void WriteLine(const char* text, const string& value0, const string& value1);
+// Requires:
+//   descriptor != NULL
+//
+// Returns:
+//   The namespace to use for given file descriptor.
+string GetFileNamespace(const FileDescriptor* descriptor);
 
-  void WriteLine(const char* text, const string& value0, const string& value1,
-                 const string& value2);
+// Requires:
+//   descriptor != NULL
+//
+// Returns:
+//   The fully-qualified C# class name.
+string GetClassName(const Descriptor* descriptor);
 
-  void WriteLine(const char* text, const string& value0, const string& value1,
-                 const string& value2, const string& value3);
- private:
-  io::Printer* printer_;
-  const char* newline_;
-};
+// Requires:
+//   descriptor != NULL
+//
+// Returns:
+//   The fully-qualified name of the C# class that provides
+//   access to the file descriptor. Proto compiler generates
+//   such class for each .proto file processed.
+std::string GetUmbrellaClassName(const FileDescriptor* descriptor);
 
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
 }  // namespace google
-#endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_WRITER_H__
+
+#endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_NAMES_H__
diff --git a/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc b/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
index 652eb6b9..fc043ec0 100644
--- a/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
@@ -49,81 +49,42 @@ namespace csharp {
 PrimitiveFieldGenerator::PrimitiveFieldGenerator(
     const FieldDescriptor* descriptor, int fieldOrdinal)
     : FieldGeneratorBase(descriptor, fieldOrdinal) {
+  // TODO(jonskeet): Make this cleaner...
+  is_value_type = descriptor->type() != FieldDescriptor::TYPE_STRING
+      && descriptor->type() != FieldDescriptor::TYPE_BYTES;
+  if (!is_value_type) {
+    variables_["has_property_check"] = variables_["property_name"] + ".Length != 0";
+    variables_["other_has_property_check"] = "other." + variables_["property_name"] + ".Length != 0";
+  }
 }
 
 PrimitiveFieldGenerator::~PrimitiveFieldGenerator() {
-
 }
 
 void PrimitiveFieldGenerator::GenerateMembers(io::Printer* printer) {
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(variables_, "private bool has$property_name$;\n");
-  }
+  // TODO(jonskeet): Work out whether we want to prevent the fields from ever being
+  // null, or whether we just handle it, in the cases of bytes and string.
+  // (Basically, should null-handling code be in the getter or the setter?)
   printer->Print(
     variables_,
     "private $type_name$ $name_def_message$;\n");
   AddDeprecatedFlag(printer);
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(
-      variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return has$property_name$; }\n"
-      "}\n");
-  }
-  AddPublicMemberAttributes(printer);
   printer->Print(
     variables_,
-    "public $type_name$ $property_name$ {\n"
+    "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $name$_; }\n"
-    "}\n");
-}
-
-void PrimitiveFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  AddDeprecatedFlag(printer);
-  if (SupportFieldPresence(descriptor_->file())) {
+    "  set {\n");
+  if (is_value_type) {
     printer->Print(
       variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return result.has$property_name$; }\n"
-      "}\n");
-  }
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return result.$property_name$; }\n"
-    "  set { Set$property_name$(value); }\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print("  PrepareBuilder();\n");
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(
-      variables_,
-      "  result.has$property_name$ = true;\n");
-  }
-  printer->Print(
-    variables_,
-    "  result.$name$_ = value;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n");
-  if (SupportFieldPresence(descriptor_->file())) {
+      "    $name$_ = value;\n");
+  } else {
     printer->Print(
       variables_,
-      "  result.has$property_name$ = false;\n");
+      "    $name$_ = pb::Preconditions.CheckNotNull(value, \"value\");\n");
   }
   printer->Print(
-    variables_,
-    "  result.$name$_ = $default_value$;\n"
-    "  return this;\n"
+    "  }\n"
     "}\n");
 }
 
@@ -135,60 +96,68 @@ void PrimitiveFieldGenerator::GenerateMergingCode(io::Printer* printer) {
     "}\n");
 }
 
-void PrimitiveFieldGenerator::GenerateBuildingCode(io::Printer* printer) {
-  // Nothing to do here for primitive types
-}
-
 void PrimitiveFieldGenerator::GenerateParsingCode(io::Printer* printer) {
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(
-      variables_,
-      "result.has$property_name$ = input.Read$capitalized_type_name$(ref result.$name$_);\n");
-  } else {
-    printer->Print(
-      variables_,
-      "input.Read$capitalized_type_name$(ref result.$name$_);\n");
-  }
+  // Note: invoke the property setter rather than writing straight to the field,
+  // so that we can normalize "null to empty" for strings and bytes.
+  printer->Print(
+    variables_,
+    "$property_name$ = input.Read$capitalized_type_name$();\n");
 }
 
 void PrimitiveFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
     "if ($has_property_check$) {\n"
-    "  output.Write$capitalized_type_name$($number$, field_names[$field_ordinal$], $property_name$);\n"
+    "  output.WriteRawTag($tag_bytes$);\n"
+    "  output.Write$capitalized_type_name$($property_name$);\n"
     "}\n");
 }
 
 void PrimitiveFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if ($has_property_check$) {\n"
-    "  size += pb::CodedOutputStream.Compute$capitalized_type_name$Size($number$, $property_name$);\n"
-    "}\n");
+    "if ($has_property_check$) {\n");
+  printer->Indent();
+  int fixedSize = GetFixedSize(descriptor_->type());
+  if (fixedSize == -1) {
+    printer->Print(
+      variables_,
+      "size += $tag_size$ + pb::CodedOutputStream.Compute$capitalized_type_name$Size($property_name$);\n");
+  } else {
+    printer->Print(
+      "size += $tag_size$ + $fixed_size$;\n",
+      "fixed_size", SimpleItoa(fixedSize),
+      "tag_size", variables_["tag_size"]);
+  }
+  printer->Outdent();
+  printer->Print("}\n");
 }
 
 void PrimitiveFieldGenerator::WriteHash(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if ($has_property_check$) {\n"
-    "  hash ^= $name$_.GetHashCode();\n"
-    "}\n");
+    "if ($has_property_check$) hash ^= $property_name$.GetHashCode();\n");
 }
 void PrimitiveFieldGenerator::WriteEquals(io::Printer* printer) {
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(
-      variables_,
-      "if (has$property_name$ != other.has$property_name$ || (has$property_name$ && !$name$_.Equals(other.$name$_))) return false;\n");
-  } else {
-    printer->Print(
-      variables_,
-      "if (!$name$_.Equals(other.$name$_)) return false;\n");
-  }
+  printer->Print(
+    variables_,
+    "if ($property_name$ != other.$property_name$) return false;\n");
 }
 void PrimitiveFieldGenerator::WriteToString(io::Printer* printer) {
   printer->Print(
     variables_,
-    "PrintField(\"$descriptor_name$\", $has_property_check$, $name$_, writer);\n");
+    "PrintField(\"$descriptor_name$\", $has_property_check$, $property_name$, writer);\n");
+}
+
+void PrimitiveFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$name$_ = other.$name$_;\n");
+}
+
+void PrimitiveFieldGenerator::GenerateCodecCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "pb::FieldCodec.For$capitalized_type_name$($tag$)");
 }
 
 PrimitiveOneofFieldGenerator::PrimitiveOneofFieldGenerator(
@@ -202,79 +171,41 @@ PrimitiveOneofFieldGenerator::~PrimitiveOneofFieldGenerator() {
 
 void PrimitiveOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
   AddDeprecatedFlag(printer);
-  if (SupportFieldPresence(descriptor_->file())) {
-    printer->Print(
-      variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return $has_property_check$; }\n"
-      "}\n");
-  }
-  AddPublicMemberAttributes(printer);
   printer->Print(
     variables_,
-    "public $type_name$ $property_name$ {\n"
+    "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : $default_value$; }\n"
-    "}\n");
-}
-
-void PrimitiveOneofFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  AddDeprecatedFlag(printer);
-  if (SupportFieldPresence(descriptor_->file())) {
+    "  set {\n");
+    if (is_value_type) {
+      printer->Print(
+        variables_,
+        "    $oneof_name$_ = value;\n");
+    } else {
+      printer->Print(
+        variables_,
+        "    $oneof_name$_ = pb::Preconditions.CheckNotNull(value, \"value\");\n");
+    }
     printer->Print(
       variables_,
-      "public bool Has$property_name$ {\n"
-      "  get { return result.$has_property_check$; }\n"
+      "    $oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
+      "  }\n"
       "}\n");
-  }
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ $property_name$ {\n"
-    "  get { return result.$has_property_check$ ? ($type_name$) result.$oneof_name$_ : $default_value$; }\n"
-    "  set { Set$property_name$(value); }\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$oneof_name$_ = value;\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n"
-    "  if (result.$has_property_check$) {\n"
-    "    result.$oneof_name$Case_ = $oneof_property_name$OneofCase.None;\n"
-    "  }\n"
-    "  return this;\n"
-    "}\n");
 }
 
-void PrimitiveOneofFieldGenerator::WriteEquals(io::Printer* printer) {
-  printer->Print(
-    variables_,
-    "if (!$property_name$.Equals(other.$property_name$)) return false;\n");
-}
 void PrimitiveOneofFieldGenerator::WriteToString(io::Printer* printer) {
   printer->Print(variables_,
     "PrintField(\"$descriptor_name$\", $has_property_check$, $oneof_name$_, writer);\n");
 }
 
 void PrimitiveOneofFieldGenerator::GenerateParsingCode(io::Printer* printer) {
-  printer->Print(
-    variables_,
-    "$type_name$ value = $default_value$;\n"
-    "if (input.Read$capitalized_type_name$(ref value)) {\n"
-    "  result.$oneof_name$_ = value;\n"
-    "  result.$oneof_name$Case_ = $oneof_property_name$OneofCase.$property_name$;\n"
-    "}\n");
+    printer->Print(
+      variables_,
+      "$property_name$ = input.Read$capitalized_type_name$();\n");
+}
+
+void PrimitiveOneofFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$property_name$ = other.$property_name$;\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_primitive_field.h b/src/google/protobuf/compiler/csharp/csharp_primitive_field.h
index 8a2d5020..8b87ebc4 100644
--- a/src/google/protobuf/compiler/csharp/csharp_primitive_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_primitive_field.h
@@ -41,17 +41,15 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class PrimitiveFieldGenerator : public FieldGeneratorBase {
  public:
   PrimitiveFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~PrimitiveFieldGenerator();
 
+  virtual void GenerateCodecCode(io::Printer* printer);
+  virtual void GenerateCloningCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
   virtual void GenerateMergingCode(io::Printer* printer);
-  virtual void GenerateBuildingCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
@@ -60,6 +58,9 @@ class PrimitiveFieldGenerator : public FieldGeneratorBase {
   virtual void WriteEquals(io::Printer* printer);
   virtual void WriteToString(io::Printer* printer);
 
+ protected:
+  bool is_value_type;
+
  private:
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(PrimitiveFieldGenerator);
 };
@@ -69,9 +70,8 @@ class PrimitiveOneofFieldGenerator : public PrimitiveFieldGenerator {
   PrimitiveOneofFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~PrimitiveOneofFieldGenerator();
 
+  virtual void GenerateCloningCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
-  virtual void WriteEquals(io::Printer* printer);
   virtual void WriteToString(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
 
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
index f5ebcfb1..625631df 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
@@ -56,187 +56,54 @@ RepeatedEnumFieldGenerator::~RepeatedEnumFieldGenerator() {
 }
 
 void RepeatedEnumFieldGenerator::GenerateMembers(io::Printer* printer) {
-  if (descriptor_->is_packed() && optimize_speed()) {
-    printer->Print(variables_, "private int $name$MemoizedSerializedSize;\n");
-  }
-  printer->Print(variables_,
-    "private pbc::PopsicleList<$type_name$> $name$_ = new pbc::PopsicleList<$type_name$>();\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public scg::IList<$type_name$> $property_name$List {\n"
-    "  get { return pbc::Lists.AsReadOnly($name$_); }\n"
-    "}\n");
-
-  // TODO(jonskeet): Redundant API calls? Possibly - include for portability though. Maybe create an option.
-  AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public int $property_name$Count {\n"
-    "  get { return $name$_.Count; }\n"
-    "}\n");
-
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return $name$_[index];\n"
-    "}\n");
-}
-
-void RepeatedEnumFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  // Note:  We can return the original list here, because we make it unmodifiable when we build
-  // We return it via IPopsicleList so that collection initializers work more pleasantly.
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public pbc::IPopsicleList<$type_name$> $property_name$List {\n"
-    "  get { return PrepareBuilder().$name$_; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public int $property_name$Count {\n"
-    "  get { return result.$property_name$Count; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return result.Get$property_name$(index);\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$(int index, $type_name$ value) {\n");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_[index] = value;\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
+    "private static readonly pb::FieldCodec<$type_name$> _repeated_$name$_codec\n"
+    "    = pb::FieldCodec.ForEnum($tag$, x => (int) x, x => ($type_name$) x);\n");
   printer->Print(variables_,
-    "public Builder Add$property_name$($type_name$ value) {\n");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(value);\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder AddRange$property_name$(scg::IEnumerable<$type_name$> values) {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(values);\n"
-    "  return this;\n"
-    "}\n");
+    "private readonly pbc::RepeatedField<$type_name$> $name$_ = new pbc::RepeatedField<$type_name$>();\n");
   AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Clear();\n"
-    "  return this;\n"
+    "$access_level$ pbc::RepeatedField<$type_name$> $property_name$ {\n"
+    "  get { return $name$_; }\n"
     "}\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateMergingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (other.$name$_.Count != 0) {\n"
-    "  result.$name$_.Add(other.$name$_);\n"
-    "}\n");
-}
-
-void RepeatedEnumFieldGenerator::GenerateBuildingCode(io::Printer* printer) {
-  printer->Print(variables_, "$name$_.MakeReadOnly();\n");
+    "$name$_.Add(other.$name$_);\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "scg::ICollection<object> unknownItems;\n"
-    "input.ReadEnumArray<$type_name$>(tag, field_name, result.$name$_, out unknownItems);\n");
-  if (!use_lite_runtime()) {
-    printer->Print(
-      variables_,
-      "if (unknownItems != null) {\n"
-      "  if (unknownFields == null) {\n"
-      "    unknownFields = pb::UnknownFieldSet.CreateBuilder(this.UnknownFields);\n"
-      "  }\n"
-      "  foreach (object rawValue in unknownItems)\n"
-      "    if (rawValue is int)\n"
-      "      unknownFields.MergeVarintField($number$, (ulong)(int)rawValue);\n"
-      "}\n");
-  }
+    "$name$_.AddEntriesFrom(input, _repeated_$name$_codec);\n");
 }
 
 void RepeatedEnumFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
-  printer->Print(variables_, "if ($name$_.Count > 0) {\n");
-  printer->Indent();
-  if (descriptor_->is_packed()) {
-    printer->Print(
-      variables_,
-      "output.WritePackedEnumArray($number$, field_names[$field_ordinal$], $name$MemoizedSerializedSize, $name$_);\n");
-  } else {
-    printer->Print(variables_,
-      "output.WriteEnumArray($number$, field_names[$field_ordinal$], $name$_);\n");
-  }
-  printer->Outdent();
-  printer->Print("}\n");
-}
-
-void RepeatedEnumFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
-  printer->Print("{\n");
-  printer->Indent();
   printer->Print(
     variables_,
-    "int dataSize = 0;\n"
-    "if ($name$_.Count > 0) {\n");
-  printer->Indent();
+    "$name$_.WriteTo(output, _repeated_$name$_codec);\n");
+}
+
+void RepeatedEnumFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {  
   printer->Print(
     variables_,
-    "foreach ($type_name$ element in $name$_) {\n"
-    "  dataSize += pb::CodedOutputStream.ComputeEnumSizeNoTag((int) element);\n"
-    "}\n"
-    "size += dataSize;\n");
-  int tagSize = internal::WireFormat::TagSize(descriptor_->number(), descriptor_->type());
-  if (descriptor_->is_packed()) {
-    printer->Print(
-      "size += $tag_size$;\n"
-      "size += pb::CodedOutputStream.ComputeRawVarint32Size((uint) dataSize);\n",
-      "tag_size", SimpleItoa(tagSize));
-  } else {
-    printer->Print(
-      "size += $tag_size$ * $name$_.Count;\n",
-      "tag_size", SimpleItoa(tagSize), "name", name());
-  }
-  printer->Outdent();
-  printer->Print("}\n");
-  // cache the data size for packed fields.
-  if (descriptor_->is_packed()) {
-    printer->Print(variables_,
-      "$name$MemoizedSerializedSize = dataSize;\n");
-  }
-  printer->Outdent();
-  printer->Print("}\n");
+    "size += $name$_.CalculateSize(_repeated_$name$_codec);\n");
 }
 
 void RepeatedEnumFieldGenerator::WriteHash(io::Printer* printer) {
   printer->Print(
     variables_,
-    "foreach($type_name$ i in $name$_)\n"
-    "  hash ^= i.GetHashCode();\n");
+    "hash ^= $name$_.GetHashCode();\n");
 }
 
 void RepeatedEnumFieldGenerator::WriteEquals(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if($name$_.Count != other.$name$_.Count) return false;\n"
-    "for(int ix=0; ix < $name$_.Count; ix++)\n"
-    "  if(!$name$_[ix].Equals(other.$name$_[ix])) return false;\n");
+    "if(!$name$_.Equals(other.$name$_)) return false;\n");
 }
 
 void RepeatedEnumFieldGenerator::WriteToString(io::Printer* printer) {
@@ -244,6 +111,14 @@ void RepeatedEnumFieldGenerator::WriteToString(io::Printer* printer) {
     "PrintField(\"$descriptor_name$\", $name$_, writer);\n");
 }
 
+void RepeatedEnumFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$name$_ = other.$name$_.Clone();\n");
+}
+
+void RepeatedEnumFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
+
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.h b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.h
index 68c3d6c9..ee50eef0 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.h
@@ -41,17 +41,17 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
+// TODO(jonskeet): Refactor repeated field support; all the implementations are *really* similar. We
+// should probably have a RepeatedFieldGeneratorBase.
 class RepeatedEnumFieldGenerator : public FieldGeneratorBase {
  public:
   RepeatedEnumFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~RepeatedEnumFieldGenerator();
 
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateFreezingCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
   virtual void GenerateMergingCode(io::Printer* printer);
-  virtual void GenerateBuildingCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
index 2ae1d579..7fbab681 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
@@ -39,6 +39,8 @@
 
 #include <google/protobuf/compiler/csharp/csharp_helpers.h>
 #include <google/protobuf/compiler/csharp/csharp_repeated_message_field.h>
+#include <google/protobuf/compiler/csharp/csharp_message_field.h>
+#include <google/protobuf/compiler/csharp/csharp_wrapper_field.h>
 
 namespace google {
 namespace protobuf {
@@ -48,7 +50,6 @@ namespace csharp {
 RepeatedMessageFieldGenerator::RepeatedMessageFieldGenerator(
     const FieldDescriptor* descriptor, int fieldOrdinal)
     : FieldGeneratorBase(descriptor, fieldOrdinal) {
-  variables_["message_or_group"] = message_or_group();
 }
 
 RepeatedMessageFieldGenerator::~RepeatedMessageFieldGenerator() {
@@ -58,162 +59,66 @@ RepeatedMessageFieldGenerator::~RepeatedMessageFieldGenerator() {
 void RepeatedMessageFieldGenerator::GenerateMembers(io::Printer* printer) {
   printer->Print(
     variables_,
-    "private pbc::PopsicleList<$type_name$> $name$_ = new pbc::PopsicleList<$type_name$>();\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public scg::IList<$type_name$> $property_name$List {\n"
-    "  get { return $name$_; }\n"
-    "}\n");
-
-  // TODO(jonskeet): Redundant API calls? Possibly - include for portability though. Maybe create an option.
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public int $property_name$Count {\n"
-    "  get { return $name$_.Count; }\n"
-    "}\n");
-
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return $name$_[index];\n"
-    "}\n");
-}
-
-void RepeatedMessageFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  // Note:  We can return the original list here, because we make it unmodifiable when we build
-  // We return it via IPopsicleList so that collection initializers work more pleasantly.
-  AddDeprecatedFlag(printer);
+    "private static readonly pb::FieldCodec<$type_name$> _repeated_$name$_codec\n"
+    "    = ");
+  // Don't want to duplicate the codec code here... maybe we should have a
+  // "create single field generator for this repeated field"
+  // function, but it doesn't seem worth it for just this.
+  if (IsWrapperType(descriptor_)) {
+    scoped_ptr<FieldGeneratorBase> single_generator(new WrapperFieldGenerator(descriptor_, fieldOrdinal_));
+    single_generator->GenerateCodecCode(printer);
+  } else {
+    scoped_ptr<FieldGeneratorBase> single_generator(new MessageFieldGenerator(descriptor_, fieldOrdinal_));
+    single_generator->GenerateCodecCode(printer);
+  }
+  printer->Print(";\n");
   printer->Print(
     variables_,
-    "public pbc::IPopsicleList<$type_name$> $property_name$List {\n"
-    "  get { return PrepareBuilder().$name$_; }\n"
-    "}\n");
+    "private readonly pbc::RepeatedField<$type_name$> $name$_ = new pbc::RepeatedField<$type_name$>();\n");
   AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public int $property_name$Count {\n"
-    "  get { return result.$property_name$Count; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return result.Get$property_name$(index);\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$(int index, $type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_[index] = value;\n"
-    "  return this;\n"
-    "}\n");
-  // Extra overload for builder (just on messages)
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$(int index, $type_name$.Builder builderForValue) {\n");
-  AddNullCheck(printer, "builderForValue");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_[index] = builderForValue.Build();\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Add$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(value);\n"
-    "  return this;\n"
-    "}\n");
-  // Extra overload for builder (just on messages)
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Add$property_name$($type_name$.Builder builderForValue) {\n");
-  AddNullCheck(printer, "builderForValue");
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(builderForValue.Build());\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder AddRange$property_name$(scg::IEnumerable<$type_name$> values) {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(values);\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Clear();\n"
-    "  return this;\n"
+    "$access_level$ pbc::RepeatedField<$type_name$> $property_name$ {\n"
+    "  get { return $name$_; }\n"
     "}\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateMergingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (other.$name$_.Count != 0) {\n"
-    "  result.$name$_.Add(other.$name$_);\n"
-    "}\n");
-}
-
-void RepeatedMessageFieldGenerator::GenerateBuildingCode(io::Printer* printer) {
-  printer->Print(variables_, "$name$_.MakeReadOnly();\n");
+    "$name$_.Add(other.$name$_);\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "input.Read$message_or_group$Array(tag, field_name, result.$name$_, $type_name$.DefaultInstance, extensionRegistry);\n");
+    "$name$_.AddEntriesFrom(input, _repeated_$name$_codec);\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if ($name$_.Count > 0) {\n"
-    "  output.Write$message_or_group$Array($number$, field_names[$field_ordinal$], $name$_);\n"
-    "}\n");
+    "$name$_.WriteTo(output, _repeated_$name$_codec);\n");
 }
 
 void RepeatedMessageFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "foreach ($type_name$ element in $property_name$List) {\n"
-    "  size += pb::CodedOutputStream.Compute$message_or_group$Size($number$, element);\n"
-    "}\n");
+    "size += $name$_.CalculateSize(_repeated_$name$_codec);\n");
 }
 
 void RepeatedMessageFieldGenerator::WriteHash(io::Printer* printer) {
   printer->Print(
     variables_,
-    "foreach($type_name$ i in $name$_)\n"
-    "  hash ^= i.GetHashCode();\n");
+    "hash ^= $name$_.GetHashCode();\n");
 }
+
 void RepeatedMessageFieldGenerator::WriteEquals(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if($name$_.Count != other.$name$_.Count) return false;\n"
-    "for(int ix=0; ix < $name$_.Count; ix++)\n"
-    "  if(!$name$_[ix].Equals(other.$name$_[ix])) return false;\n");
+    "if(!$name$_.Equals(other.$name$_)) return false;\n");
 }
+
 void RepeatedMessageFieldGenerator::WriteToString(io::Printer* printer) {
   variables_["field_name"] = GetFieldName(descriptor_);
   printer->Print(
@@ -221,6 +126,14 @@ void RepeatedMessageFieldGenerator::WriteToString(io::Printer* printer) {
     "PrintField(\"$field_name$\", $name$_, writer);\n");
 }
 
+void RepeatedMessageFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$name$_ = other.$name$_.Clone();\n");
+}
+
+void RepeatedMessageFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
+
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.h b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.h
index 9db76939..cf601c7e 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.h
@@ -41,17 +41,15 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class RepeatedMessageFieldGenerator : public FieldGeneratorBase {
  public:
   RepeatedMessageFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~RepeatedMessageFieldGenerator();
 
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateFreezingCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
   virtual void GenerateMergingCode(io::Printer* printer);
-  virtual void GenerateBuildingCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
index e27458bb..1163ce73 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
@@ -56,183 +56,67 @@ RepeatedPrimitiveFieldGenerator::~RepeatedPrimitiveFieldGenerator() {
 }
 
 void RepeatedPrimitiveFieldGenerator::GenerateMembers(io::Printer* printer) {
-  if (descriptor_->is_packed() && optimize_speed()) {
-    printer->Print(variables_, "private int $name$MemoizedSerializedSize;\n");
-  }
-  printer->Print(variables_,
-    "private pbc::PopsicleList<$type_name$> $name$_ = new pbc::PopsicleList<$type_name$>();\n");
-  AddPublicMemberAttributes(printer);
   printer->Print(
     variables_,
-    "public scg::IList<$type_name$> $property_name$List {\n"
-    "  get { return pbc::Lists.AsReadOnly($name$_); }\n"
-    "}\n");
-
-  // TODO(jonskeet): Redundant API calls? Possibly - include for portability though. Maybe create an option.
+    "private static readonly pb::FieldCodec<$type_name$> _repeated_$name$_codec\n"
+    "    = pb::FieldCodec.For$capitalized_type_name$($tag$);\n");
+  printer->Print(variables_,
+    "private readonly pbc::RepeatedField<$type_name$> $name$_ = new pbc::RepeatedField<$type_name$>();\n");
   AddDeprecatedFlag(printer);
   printer->Print(
     variables_,
-    "public int $property_name$Count {\n"
-    "  get { return $name$_.Count; }\n"
+    "$access_level$ pbc::RepeatedField<$type_name$> $property_name$ {\n"
+    "  get { return $name$_; }\n"
     "}\n");
+}
 
-  AddPublicMemberAttributes(printer);
+void RepeatedPrimitiveFieldGenerator::GenerateMergingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return $name$_[index];\n"
-    "}\n");
+    "$name$_.Add(other.$name$_);\n");
 }
 
-void RepeatedPrimitiveFieldGenerator::GenerateBuilderMembers(io::Printer* printer) {
-  // Note:  We can return the original list here, because we make it unmodifiable when we build
-  // We return it via IPopsicleList so that collection initializers work more pleasantly.
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public pbc::IPopsicleList<$type_name$> $property_name$List {\n"
-    "  get { return PrepareBuilder().$name$_; }\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
-  printer->Print(
-    variables_,
-    "public int $property_name$Count {\n"
-    "  get { return result.$property_name$Count; }\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public $type_name$ Get$property_name$(int index) {\n"
-    "  return result.Get$property_name$(index);\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public Builder Set$property_name$(int index, $type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_[index] = value;\n"
-    "  return this;\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public Builder Add$property_name$($type_name$ value) {\n");
-  AddNullCheck(printer);
-  printer->Print(
-    variables_,
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(value);\n"
-    "  return this;\n"
-    "}\n");
-  AddPublicMemberAttributes(printer);
-  printer->Print(
-    variables_,
-    "public Builder AddRange$property_name$(scg::IEnumerable<$type_name$> values) {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Add(values);\n"
-    "  return this;\n"
-    "}\n");
-  AddDeprecatedFlag(printer);
+void RepeatedPrimitiveFieldGenerator::GenerateParsingCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "public Builder Clear$property_name$() {\n"
-    "  PrepareBuilder();\n"
-    "  result.$name$_.Clear();\n"
-    "  return this;\n"
-    "}\n");
+    "$name$_.AddEntriesFrom(input, _repeated_$name$_codec);\n");
 }
 
-void RepeatedPrimitiveFieldGenerator::GenerateMergingCode(io::Printer* printer) {
+void RepeatedPrimitiveFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if (other.$name$_.Count != 0) {\n"
-    "  result.$name$_.Add(other.$name$_);\n"
-    "}\n");
+    "$name$_.WriteTo(output, _repeated_$name$_codec);\n");
 }
 
-void RepeatedPrimitiveFieldGenerator::GenerateBuildingCode(io::Printer* printer) {
-  printer->Print(variables_, "$name$_.MakeReadOnly();\n");
-}
-
-void RepeatedPrimitiveFieldGenerator::GenerateParsingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "input.Read$capitalized_type_name$Array(tag, field_name, result.$name$_);\n");
-}
-
-void RepeatedPrimitiveFieldGenerator::GenerateSerializationCode(
-    io::Printer* printer) {
-  printer->Print(variables_, "if ($name$_.Count > 0) {\n");
-  printer->Indent();
-  if (descriptor_->is_packed()) {
-    printer->Print(variables_,
-      "output.WritePacked$capitalized_type_name$Array($number$, field_names[$field_ordinal$], $name$MemoizedSerializedSize, $name$_);\n");
-  } else {
-    printer->Print(variables_,
-      "output.Write$capitalized_type_name$Array($number$, field_names[$field_ordinal$], $name$_);\n");
-  }
-  printer->Outdent();
-  printer->Print("}\n");
-}
-
-void RepeatedPrimitiveFieldGenerator::GenerateSerializedSizeCode(
-    io::Printer* printer) {
-  printer->Print("{\n");
-  printer->Indent();
-  printer->Print("int dataSize = 0;\n");
-  int fixedSize = GetFixedSize(descriptor_->type());
-  if (fixedSize == -1) {
-    printer->Print(
-      variables_,
-      "foreach ($type_name$ element in $property_name$List) {\n"
-      "  dataSize += pb::CodedOutputStream.Compute$capitalized_type_name$SizeNoTag(element);\n"
-      "}\n");
-  } else {
-    printer->Print(
-      "dataSize = $size$ * $name$_.Count;\n",
-      "size", SimpleItoa(fixedSize), "name", name());
-  }
-  printer->Print("size += dataSize;\n");
-  int tagSize = internal::WireFormat::TagSize(descriptor_->number(), descriptor_->type());
-  if (descriptor_->is_packed()) {
-    printer->Print(
-      "if ($name$_.Count != 0) {\n"
-      "  size += $tag_size$ + pb::CodedOutputStream.ComputeInt32SizeNoTag(dataSize);\n"
-      "}\n",
-      "name", name(), "tag_size", SimpleItoa(tagSize));
-  } else {
-    printer->Print(
-      "size += $tag_size$ * $name$_.Count;\n",
-      "tag_size", SimpleItoa(tagSize), "name", name());
-  }
-  // cache the data size for packed fields.
-  if (descriptor_->is_packed()) {
-    printer->Print(variables_, "$name$MemoizedSerializedSize = dataSize;\n");
-  }
-  printer->Outdent();
-  printer->Print("}\n");
+void RepeatedPrimitiveFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "size += $name$_.CalculateSize(_repeated_$name$_codec);\n");
 }
 
 void RepeatedPrimitiveFieldGenerator::WriteHash(io::Printer* printer) {
   printer->Print(
     variables_,
-    "foreach($type_name$ i in $name$_)\n"
-    "  hash ^= i.GetHashCode();\n");
+    "hash ^= $name$_.GetHashCode();\n");
 }
 void RepeatedPrimitiveFieldGenerator::WriteEquals(io::Printer* printer) {
   printer->Print(
     variables_,
-    "if($name$_.Count != other.$name$_.Count) return false;\n"
-    "for(int ix=0; ix < $name$_.Count; ix++)\n"
-    "  if(!$name$_[ix].Equals(other.$name$_[ix])) return false;\n");
+    "if(!$name$_.Equals(other.$name$_)) return false;\n");
 }
 void RepeatedPrimitiveFieldGenerator::WriteToString(io::Printer* printer) {
   printer->Print(variables_,
     "PrintField(\"$descriptor_name$\", $name$_, writer);\n");
 }
 
+void RepeatedPrimitiveFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$name$_ = other.$name$_.Clone();\n");
+}
+
+void RepeatedPrimitiveFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
+}
+
 }  // namespace csharp
 }  // namespace compiler
 }  // namespace protobuf
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h
index 50af9dda..f1ceeb50 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h
@@ -41,17 +41,15 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class RepeatedPrimitiveFieldGenerator : public FieldGeneratorBase {
  public:
   RepeatedPrimitiveFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
   ~RepeatedPrimitiveFieldGenerator();
 
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateFreezingCode(io::Printer* printer);
   virtual void GenerateMembers(io::Printer* printer);
-  virtual void GenerateBuilderMembers(io::Printer* printer);
   virtual void GenerateMergingCode(io::Printer* printer);
-  virtual void GenerateBuildingCode(io::Printer* printer);
   virtual void GenerateParsingCode(io::Printer* printer);
   virtual void GenerateSerializationCode(io::Printer* printer);
   virtual void GenerateSerializedSizeCode(io::Printer* printer);
diff --git a/src/google/protobuf/compiler/csharp/csharp_source_generator_base.cc b/src/google/protobuf/compiler/csharp/csharp_source_generator_base.cc
index c52f6092..735d164a 100644
--- a/src/google/protobuf/compiler/csharp/csharp_source_generator_base.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_source_generator_base.cc
@@ -47,14 +47,6 @@ namespace csharp {
 
 SourceGeneratorBase::SourceGeneratorBase(const FileDescriptor* descriptor)
     : descriptor_(descriptor) {
-  optimizeSize_ = (descriptor->options().optimize_for()
-      == FileOptions::CODE_SIZE);
-  optimizeSpeed_ = (descriptor->options().optimize_for() == FileOptions::SPEED);
-  useLiteRuntime_ = (descriptor->options().optimize_for()
-      == FileOptions::LITE_RUNTIME);
-
-  optimizeSpeed_ |= useLiteRuntime_;
-  runtimeSuffix_ = useLiteRuntime_ ? "Lite" : "";
 }
 
 SourceGeneratorBase::~SourceGeneratorBase() {
@@ -65,7 +57,7 @@ void SourceGeneratorBase::WriteGeneratedCodeAttributes(io::Printer* printer) {
 }
 
 std::string SourceGeneratorBase::class_access_level() {
-  return "public";  // public_classes is always on.
+  return IsDescriptorProto(descriptor_) ? "internal" : "public";  // public_classes is always on.
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_source_generator_base.h b/src/google/protobuf/compiler/csharp/csharp_source_generator_base.h
index 61c19511..6caef171 100644
--- a/src/google/protobuf/compiler/csharp/csharp_source_generator_base.h
+++ b/src/google/protobuf/compiler/csharp/csharp_source_generator_base.h
@@ -47,27 +47,10 @@ class SourceGeneratorBase {
 
   std::string class_access_level();
 
-  bool optimize_size() {
-    return optimizeSize_;
-  }
-  bool optimize_speed() {
-    return optimizeSpeed_;
-  }
-  bool use_lite_runtime() {
-    return useLiteRuntime_;
-  }
-  std::string runtime_suffix() {
-    return runtimeSuffix_;
-  }
-
   void WriteGeneratedCodeAttributes(io::Printer* printer);
 
  private:
   const FileDescriptor* descriptor_;
-  bool optimizeSize_;
-  bool optimizeSpeed_;
-  bool useLiteRuntime_;
-  std::string runtimeSuffix_;
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(SourceGeneratorBase);
 };
diff --git a/src/google/protobuf/compiler/csharp/csharp_umbrella_class.cc b/src/google/protobuf/compiler/csharp/csharp_umbrella_class.cc
index b14bf5e8..0ffae3d4 100644
--- a/src/google/protobuf/compiler/csharp/csharp_umbrella_class.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_umbrella_class.cc
@@ -36,12 +36,14 @@
 #include <google/protobuf/descriptor.pb.h>
 #include <google/protobuf/io/printer.h>
 #include <google/protobuf/io/zero_copy_stream.h>
+#include <google/protobuf/stubs/strutil.h>
+
 
-#include <google/protobuf/compiler/csharp/csharp_umbrella_class.h>
 #include <google/protobuf/compiler/csharp/csharp_enum.h>
-#include <google/protobuf/compiler/csharp/csharp_extension.h>
 #include <google/protobuf/compiler/csharp/csharp_helpers.h>
 #include <google/protobuf/compiler/csharp/csharp_message.h>
+#include <google/protobuf/compiler/csharp/csharp_names.h>
+#include <google/protobuf/compiler/csharp/csharp_umbrella_class.h>
 
 namespace google {
 namespace protobuf {
@@ -52,8 +54,8 @@ UmbrellaClassGenerator::UmbrellaClassGenerator(const FileDescriptor* file)
     : SourceGeneratorBase(file),
       file_(file) {
   namespace_ = GetFileNamespace(file);
-  umbrellaClassname_ = GetFileUmbrellaClassname(file);
-  umbrellaNamespace_ = GetFileUmbrellaNamespace(file);
+  umbrellaClassname_ = GetUmbrellaClassUnqualifiedName(file);
+  umbrellaNamespace_ = GetUmbrellaClassNestedNamespace(file);
 }
 
 UmbrellaClassGenerator::~UmbrellaClassGenerator() {
@@ -61,30 +63,8 @@ UmbrellaClassGenerator::~UmbrellaClassGenerator() {
 
 void UmbrellaClassGenerator::Generate(io::Printer* printer) {
   WriteIntroduction(printer);
-  WriteExtensionRegistration(printer);
 
-  // write children: Extensions
-  if (file_->extension_count() > 0) {
-    printer->Print("#region Extensions\n");
-    for (int i = 0; i < file_->extension_count(); i++) {
-      ExtensionGenerator extensionGenerator(file_->extension(i));
-      extensionGenerator.Generate(printer);
-    }
-    printer->Print("#endregion\n");
-    printer->Print("\n");
-  }
-
-  printer->Print("#region Static variables\n");
-  for (int i = 0; i < file_->message_type_count(); i++) {
-    MessageGenerator messageGenerator(file_->message_type(i));
-    messageGenerator.GenerateStaticVariables(printer);
-  }
-  printer->Print("#endregion\n");
-  if (!use_lite_runtime()) {
-    WriteDescriptor(printer);
-  } else {
-    WriteLiteExtensions(printer);
-  }
+  WriteDescriptor(printer);
   // Close the class declaration.
   printer->Outdent();
   printer->Print("}\n");
@@ -134,9 +114,9 @@ void UmbrellaClassGenerator::WriteIntroduction(io::Printer* printer) {
     "#pragma warning disable 1591, 0612, 3021\n"
     "#region Designer generated code\n"
     "\n"
-    "using pb = global::Google.ProtocolBuffers;\n"
-    "using pbc = global::Google.ProtocolBuffers.Collections;\n"
-    "using pbd = global::Google.ProtocolBuffers.Descriptors;\n"
+    "using pb = global::Google.Protobuf;\n"
+    "using pbc = global::Google.Protobuf.Collections;\n"
+    "using pbr = global::Google.Protobuf.Reflection;\n"
     "using scg = global::System.Collections.Generic;\n",
     "file_name", file_->name());
 
@@ -165,31 +145,13 @@ void UmbrellaClassGenerator::WriteIntroduction(io::Printer* printer) {
   printer->Indent();
 }
 
-void UmbrellaClassGenerator::WriteExtensionRegistration(io::Printer* printer) {
-  printer->Print(
-    "#region Extension registration\n"
-    "public static void RegisterAllExtensions(pb::ExtensionRegistry registry) {\n");
-  printer->Indent();
-  for (int i = 0; i < file_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(file_->extension(i));
-    extensionGenerator.GenerateExtensionRegistrationCode(printer);
-  }
-  for (int i = 0; i < file_->message_type_count(); i++) {
-    MessageGenerator messageGenerator(file_->message_type(i));
-    messageGenerator.GenerateExtensionRegistrationCode(printer);
-  }
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("#endregion\n");
-}
-
 void UmbrellaClassGenerator::WriteDescriptor(io::Printer* printer) {
   printer->Print(
     "#region Descriptor\n"
-    "public static pbd::FileDescriptor Descriptor {\n"
+    "public static pbr::FileDescriptor Descriptor {\n"
     "  get { return descriptor; }\n"
     "}\n"
-    "private static pbd::FileDescriptor descriptor;\n"
+    "private static pbr::FileDescriptor descriptor;\n"
     "\n"
     "static $umbrella_class_name$() {\n",
     "umbrella_class_name", umbrellaClassname_);
@@ -207,82 +169,124 @@ void UmbrellaClassGenerator::WriteDescriptor(io::Printer* printer) {
     printer->Print("\"$base64$\", \n", "base64", base64.substr(0, 60));
     base64 = base64.substr(60);
   }
-  printer->Outdent();
   printer->Print("\"$base64$\"));\n", "base64", base64);
   printer->Outdent();
   printer->Outdent();
-  printer->Print(
-    "pbd::FileDescriptor.InternalDescriptorAssigner assigner = delegate(pbd::FileDescriptor root) {\n");
-  printer->Indent();
-  printer->Print("descriptor = root;\n");
-  for (int i = 0; i < file_->message_type_count(); i++) {
-    MessageGenerator messageGenerator(file_->message_type(i));
-    messageGenerator.GenerateStaticVariableInitializers(printer);
-  }
-  for (int i = 0; i < file_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(file_->extension(i));
-    extensionGenerator.GenerateStaticVariableInitializers(printer);
-  }
-
-  if (uses_extensions()) {
-    // Must construct an ExtensionRegistry containing all possible extensions
-    // and return it.
-    printer->Print(
-        "pb::ExtensionRegistry registry = pb::ExtensionRegistry.CreateInstance();\n");
-    printer->Print("RegisterAllExtensions(registry);\n");
-    for (int i = 0; i < file_->dependency_count(); i++) {
-      printer->Print("$dependency$.RegisterAllExtensions(registry);\n",
-		     "dependency", GetFullUmbrellaClassName(file_->dependency(i)));
-    }
-    printer->Print("return registry;\n");
-  } else {
-    printer->Print("return null;\n");
-  }
   printer->Outdent();
-  printer->Print("};\n");
 
   // -----------------------------------------------------------------
-  // Invoke internalBuildGeneratedFileFrom() to build the file.
+  // Invoke InternalBuildGeneratedFileFrom() to build the file.
   printer->Print(
-      "pbd::FileDescriptor.InternalBuildGeneratedFileFrom(descriptorData,\n");
-  printer->Print("    new pbd::FileDescriptor[] {\n");
+      "descriptor = pbr::FileDescriptor.InternalBuildGeneratedFileFrom(descriptorData,\n");
+  printer->Print("    new pbr::FileDescriptor[] { ");
   for (int i = 0; i < file_->dependency_count(); i++) {
     printer->Print(
-      "    $full_umbrella_class_name$.Descriptor, \n",
+      "$full_umbrella_class_name$.Descriptor, ",
       "full_umbrella_class_name",
-      GetFullUmbrellaClassName(file_->dependency(i)));
+      GetUmbrellaClassName(file_->dependency(i)));
+  }
+  printer->Print("},\n"
+      "    new pbr::GeneratedCodeInfo(");
+  // Specify all the generated code information, recursively.
+  if (file_->enum_type_count() > 0) {
+      printer->Print("new[] {");
+      for (int i = 0; i < file_->enum_type_count(); i++) {
+          printer->Print("typeof($type_name$), ", "type_name", GetClassName(file_->enum_type(i)));
+      }
+      printer->Print("}, ");
+  }
+  else {
+      printer->Print("null, ");
+  }
+  if (file_->message_type_count() > 0) {
+      printer->Print("new pbr::GeneratedCodeInfo[] {\n");
+      printer->Indent();
+      printer->Indent();
+      printer->Indent();
+      for (int i = 0; i < file_->message_type_count(); i++) {
+          WriteGeneratedCodeInfo(file_->message_type(i), printer, i == file_->message_type_count() - 1);
+      }
+      printer->Outdent();
+      printer->Print("\n}));\n");
+      printer->Outdent();
+      printer->Outdent();
+  }
+  else {
+      printer->Print("null));\n");
   }
-  printer->Print("    }, assigner);\n");
+
   printer->Outdent();
   printer->Print("}\n");
   printer->Print("#endregion\n\n");
 }
 
-void UmbrellaClassGenerator::WriteLiteExtensions(io::Printer* printer) {
-  printer->Print(
-    "#region Extensions\n"
-    "internal static readonly object Descriptor;\n"
-    "static $umbrella_class_name$() {\n",
-    "umbrella_class_name", umbrellaClassname_);
-  printer->Indent();
-  printer->Print("Descriptor = null;\n");
-  for (int i = 0; i < file_->message_type_count(); i++) {
-    MessageGenerator messageGenerator(file_->message_type(i));
-    messageGenerator.GenerateStaticVariableInitializers(printer);
+// Write out the generated code for a particular message. This consists of the CLR type, property names
+// corresponding to fields, names corresponding to oneofs, nested enums, and nested types. Each array part
+// can be specified as null if it would be empty, to make the generated code somewhat simpler to read.
+// We write a line break at the end of each generated code info, so that in the final file we'll see all
+// the types, pre-ordered depth first, one per line. The indentation will be slightly unusual,
+// in that it will look like a single array when it's actually constructing a tree, but it'll be easy to
+// read even with multiple levels of nesting.
+// The "last" parameter indicates whether this message descriptor is the last one being printed in this immediate
+// context. It governs whether or not a trailing comma and newline is written after the constructor, effectively
+// just controlling the formatting in the generated code.
+void UmbrellaClassGenerator::WriteGeneratedCodeInfo(const Descriptor* descriptor, io::Printer* printer, bool last) {
+  if (IsMapEntryMessage(descriptor)) {
+    printer->Print("null, ");
+    return;
   }
-  for (int i = 0; i < file_->extension_count(); i++) {
-    ExtensionGenerator extensionGenerator(file_->extension(i));
-    extensionGenerator.GenerateStaticVariableInitializers(printer);
+  // Generated message type
+  printer->Print("new pbr::GeneratedCodeInfo(typeof($type_name$), ", "type_name", GetClassName(descriptor));
+  
+  // Fields
+  if (descriptor->field_count() > 0) {
+      std::vector<std::string> fields;
+      for (int i = 0; i < descriptor->field_count(); i++) {
+          fields.push_back(GetPropertyName(descriptor->field(i)));
+      }
+      printer->Print("new[]{ \"$fields$\" }, ", "fields", JoinStrings(fields, "\", \""));
+  }
+  else {
+      printer->Print("null, ");
+  }
+
+  // Oneofs
+  if (descriptor->oneof_decl_count() > 0) {
+      std::vector<std::string> oneofs;
+      for (int i = 0; i < descriptor->oneof_decl_count(); i++) {
+          oneofs.push_back(UnderscoresToCamelCase(descriptor->oneof_decl(i)->name(), true));
+      }
+      printer->Print("new[]{ \"$oneofs$\" }, ", "oneofs", JoinStrings(oneofs, "\", \""));
+  }
+  else {
+      printer->Print("null, ");
+  }
+
+  // Nested enums
+  if (descriptor->enum_type_count() > 0) {
+      std::vector<std::string> enums;
+      for (int i = 0; i < descriptor->enum_type_count(); i++) {
+          enums.push_back(GetClassName(descriptor->enum_type(i)));
+      }
+      printer->Print("new[]{ typeof($enums$) }, ", "enums", JoinStrings(enums, "), typeof("));
+  }
+  else {
+      printer->Print("null, ");
   }
-  printer->Outdent();
-  printer->Print("}\n");
-  printer->Print("#endregion\n\n");
-}
 
-bool UmbrellaClassGenerator::uses_extensions() {
-  // TODO(jtattermusch): implement recursive descent that looks for extensions.
-  // For now, we conservatively assume that extensions are used.
-  return true;
+  // Nested types
+  if (descriptor->nested_type_count() > 0) {
+      // Need to specify array type explicitly here, as all elements may be null. 
+      printer->Print("new pbr::GeneratedCodeInfo[] { ");
+      for (int i = 0; i < descriptor->nested_type_count(); i++) {
+          WriteGeneratedCodeInfo(descriptor->nested_type(i), printer, i == descriptor->nested_type_count() - 1);
+      }
+      printer->Print("}");
+  }
+  else {
+      printer->Print("null");
+  }
+  printer->Print(last ? ")" : "),\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_umbrella_class.h b/src/google/protobuf/compiler/csharp/csharp_umbrella_class.h
index 83e1f347..b8bd2133 100644
--- a/src/google/protobuf/compiler/csharp/csharp_umbrella_class.h
+++ b/src/google/protobuf/compiler/csharp/csharp_umbrella_class.h
@@ -41,8 +41,6 @@ namespace protobuf {
 namespace compiler {
 namespace csharp {
 
-class Writer;
-
 class UmbrellaClassGenerator : public SourceGeneratorBase {
  public:
   UmbrellaClassGenerator(const FileDescriptor* file);
@@ -58,11 +56,8 @@ class UmbrellaClassGenerator : public SourceGeneratorBase {
   std::string umbrellaNamespace_;
 
   void WriteIntroduction(io::Printer* printer);
-  void WriteExtensionRegistration(io::Printer* printer);
   void WriteDescriptor(io::Printer* printer);
-  void WriteLiteExtensions(io::Printer* printer);
-
-  bool uses_extensions();
+  void WriteGeneratedCodeInfo(const Descriptor* descriptor, io::Printer* printer, bool last);
 
   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(UmbrellaClassGenerator);
 };
@@ -73,4 +68,3 @@ class UmbrellaClassGenerator : public SourceGeneratorBase {
 }  // namespace google
 
 #endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_UMBRELLA_CLASS_H__
-
diff --git a/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc
new file mode 100644
index 00000000..44f832bf
--- /dev/null
+++ b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc
@@ -0,0 +1,207 @@
+// 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.
+
+#include <sstream>
+
+#include <google/protobuf/compiler/code_generator.h>
+#include <google/protobuf/compiler/plugin.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/descriptor.pb.h>
+#include <google/protobuf/io/printer.h>
+#include <google/protobuf/io/zero_copy_stream.h>
+
+#include <google/protobuf/compiler/csharp/csharp_helpers.h>
+#include <google/protobuf/compiler/csharp/csharp_wrapper_field.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace csharp {
+
+WrapperFieldGenerator::WrapperFieldGenerator(const FieldDescriptor* descriptor,
+                                       int fieldOrdinal)
+    : FieldGeneratorBase(descriptor, fieldOrdinal) {
+  variables_["has_property_check"] = name() + "_ != null";
+  variables_["has_not_property_check"] = name() + "_ == null";
+  const FieldDescriptor* wrapped_field = descriptor->message_type()->field(0);
+  is_value_type = wrapped_field->type() != FieldDescriptor::TYPE_STRING &&
+      wrapped_field->type() != FieldDescriptor::TYPE_BYTES;
+  if (is_value_type) {
+    variables_["nonnullable_type_name"] = type_name(wrapped_field);
+  }
+}
+
+WrapperFieldGenerator::~WrapperFieldGenerator() {
+}
+
+void WrapperFieldGenerator::GenerateMembers(io::Printer* printer) {
+  printer->Print(
+        variables_,
+        "private static readonly pb::FieldCodec<$type_name$> _single_$name$_codec = ");
+  GenerateCodecCode(printer);
+  printer->Print(
+    variables_,
+    ";\n"
+    "private $type_name$ $name$_;\n");
+  AddDeprecatedFlag(printer);
+  printer->Print(
+    variables_,
+    "$access_level$ $type_name$ $property_name$ {\n"
+    "  get { return $name$_; }\n"
+    "  set {\n"
+    "    $name$_ = value;\n"
+    "  }\n"
+    "}\n");
+}
+
+void WrapperFieldGenerator::GenerateMergingCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if (other.$has_property_check$) {\n"
+    "  if ($has_not_property_check$ || other.$property_name$ != $default_value$) {\n"
+    "    $property_name$ = other.$property_name$;\n"
+    "  }\n"
+    "}\n");
+}
+
+void WrapperFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "$type_name$ value = _single_$name$_codec.Read(input);\n"
+    "if ($has_not_property_check$ || value != $default_value$) {\n"
+    "  $property_name$ = value;\n"
+    "}\n");
+}
+
+void WrapperFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if ($has_property_check$) {\n"
+    "  _single_$name$_codec.WriteTagAndValue(output, $property_name$);\n"
+    "}\n");
+}
+
+void WrapperFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if ($has_property_check$) {\n"
+    "  size += _single_$name$_codec.CalculateSizeWithTag($property_name$);\n"
+    "}\n");
+}
+
+void WrapperFieldGenerator::WriteHash(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if ($has_property_check$) hash ^= $property_name$.GetHashCode();\n");
+}
+
+void WrapperFieldGenerator::WriteEquals(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "if ($property_name$ != other.$property_name$) return false;\n");
+}
+
+void WrapperFieldGenerator::WriteToString(io::Printer* printer) {
+  // TODO: Implement if we ever actually need it...
+}
+
+void WrapperFieldGenerator::GenerateCloningCode(io::Printer* printer) {
+  printer->Print(variables_,
+    "$property_name$ = other.$property_name$;\n");
+}
+
+void WrapperFieldGenerator::GenerateCodecCode(io::Printer* printer) {
+  if (is_value_type) {
+    printer->Print(
+      variables_,
+      "pb::FieldCodec.ForStructWrapper<$nonnullable_type_name$>($tag$)");
+  } else {
+    printer->Print(
+      variables_,
+      "pb::FieldCodec.ForClassWrapper<$type_name$>($tag$)");
+  }
+}
+
+WrapperOneofFieldGenerator::WrapperOneofFieldGenerator(const FieldDescriptor* descriptor,
+    int fieldOrdinal)
+    : WrapperFieldGenerator(descriptor, fieldOrdinal) {
+    SetCommonOneofFieldVariables(&variables_);
+}
+
+WrapperOneofFieldGenerator::~WrapperOneofFieldGenerator() {
+}
+
+void WrapperOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
+  // Note: deliberately _oneof_$name$_codec, not _$oneof_name$_codec... we have one codec per field.
+  printer->Print(
+        variables_,
+        "private static readonly pb::FieldCodec<$type_name$> _oneof_$name$_codec = ");
+  GenerateCodecCode(printer);
+  printer->Print(";\n");
+  AddDeprecatedFlag(printer);
+  printer->Print(
+    variables_,
+    "$access_level$ $type_name$ $property_name$ {\n"
+    "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : ($type_name$) null; }\n"
+    "  set {\n"
+    "    $oneof_name$_ = value;\n"
+    "    $oneof_name$Case_ = value == null ? $oneof_property_name$OneofCase.None : $oneof_property_name$OneofCase.$property_name$;\n"
+    "  }\n"
+    "}\n");
+}
+
+void WrapperOneofFieldGenerator::GenerateParsingCode(io::Printer* printer) {
+  printer->Print(
+    variables_,
+    "$property_name$ = _oneof_$name$_codec.Read(input);\n");
+}
+
+void WrapperOneofFieldGenerator::GenerateSerializationCode(io::Printer* printer) {
+  // TODO: I suspect this is wrong...
+  printer->Print(
+    variables_,
+    "if ($has_property_check$) {\n"
+    "  _oneof_$name$_codec.WriteTagAndValue(output, ($type_name$) $oneof_name$_);\n"
+    "}\n");
+}
+
+void WrapperOneofFieldGenerator::GenerateSerializedSizeCode(io::Printer* printer) {
+  // TODO: I suspect this is wrong...
+  printer->Print(
+    variables_,
+    "if ($has_property_check$) {\n"
+    "  size += _oneof_$name$_codec.CalculateSizeWithTag($property_name$);\n"
+    "}\n");
+}
+
+}  // namespace csharp
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/compiler/csharp/csharp_wrapper_field.h b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.h
new file mode 100644
index 00000000..6e2414af
--- /dev/null
+++ b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.h
@@ -0,0 +1,85 @@
+// 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.
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_CSHARP_WRAPPER_FIELD_H__
+#define GOOGLE_PROTOBUF_COMPILER_CSHARP_WRAPPER_FIELD_H__
+
+#include <string>
+
+#include <google/protobuf/compiler/code_generator.h>
+#include <google/protobuf/compiler/csharp/csharp_field_base.h>
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace csharp {
+
+class WrapperFieldGenerator : public FieldGeneratorBase {
+ public:
+  WrapperFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
+  ~WrapperFieldGenerator();
+
+  virtual void GenerateCodecCode(io::Printer* printer);
+  virtual void GenerateCloningCode(io::Printer* printer);
+  virtual void GenerateMembers(io::Printer* printer);
+  virtual void GenerateMergingCode(io::Printer* printer);
+  virtual void GenerateParsingCode(io::Printer* printer);
+  virtual void GenerateSerializationCode(io::Printer* printer);
+  virtual void GenerateSerializedSizeCode(io::Printer* printer);
+
+  virtual void WriteHash(io::Printer* printer);
+  virtual void WriteEquals(io::Printer* printer);
+  virtual void WriteToString(io::Printer* printer);
+
+ private:
+  bool is_value_type; // True for int32 etc; false for bytes and string
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(WrapperFieldGenerator);
+};
+
+class WrapperOneofFieldGenerator : public WrapperFieldGenerator {
+ public:
+  WrapperOneofFieldGenerator(const FieldDescriptor* descriptor, int fieldOrdinal);
+  ~WrapperOneofFieldGenerator();
+
+  virtual void GenerateMembers(io::Printer* printer);
+  virtual void GenerateParsingCode(io::Printer* printer);
+  virtual void GenerateSerializationCode(io::Printer* printer);
+  virtual void GenerateSerializedSizeCode(io::Printer* printer);
+
+ private:
+  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(WrapperOneofFieldGenerator);
+};
+
+}  // namespace csharp
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_COMPILER_CSHARP_WRAPPER_FIELD_H__
diff --git a/src/google/protobuf/compiler/csharp/csharp_writer.cc b/src/google/protobuf/compiler/csharp/csharp_writer.cc
deleted file mode 100644
index 2bcafde5..00000000
--- a/src/google/protobuf/compiler/csharp/csharp_writer.cc
+++ /dev/null
@@ -1,136 +0,0 @@
-// 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.
-
-// Author: kenton@google.com (Kenton Varda)
-//  Based on original Protocol Buffers design by
-//  Sanjay Ghemawat, Jeff Dean, and others.
-
-#include <algorithm>
-#include <google/protobuf/stubs/hash.h>
-#include <limits>
-#include <vector>
-
-#include <google/protobuf/compiler/csharp/csharp_writer.h>
-#include <google/protobuf/descriptor.pb.h>
-#include <google/protobuf/io/printer.h>
-#include <google/protobuf/wire_format.h>
-#include <google/protobuf/stubs/strutil.h>
-#include <google/protobuf/stubs/substitute.h>
-
-#include <google/protobuf/compiler/csharp/csharp_field_base.h>
-#include <google/protobuf/compiler/csharp/csharp_enum_field.h>
-#include <google/protobuf/compiler/csharp/csharp_message_field.h>
-#include <google/protobuf/compiler/csharp/csharp_primitive_field.h>
-#include <google/protobuf/compiler/csharp/csharp_repeated_enum_field.h>
-#include <google/protobuf/compiler/csharp/csharp_repeated_message_field.h>
-#include <google/protobuf/compiler/csharp/csharp_repeated_primitive_field.h>
-
-namespace google {
-namespace protobuf {
-namespace compiler {
-namespace csharp {
-
-Writer::Writer(google::protobuf::io::Printer* printer)
-    : printer_(printer),
-      newline_("\n") {
-  // TODO(jtattermusch): make newline customizable.
-}
-
-Writer::~Writer() {
-}
-
-void Writer::Indent() {
-  printer_->Indent();
-}
-
-void Writer::Outdent() {
-  printer_->Outdent();
-}
-
-void Writer::Write(const char* text) {
-  printer_->Print(text);
-}
-
-void Writer::Write(const char* text, const string& value0) {
-  printer_->Print(text, "0", value0);
-}
-
-void Writer::Write(const char* text, const string& value0,
-                   const string& value1) {
-  printer_->Print(text, "0", value0, "1", value1);
-}
-
-void Writer::Write(const char* text, const string& value0, const string& value1,
-                   const string& value2) {
-  printer_->Print(text, "0", value0, "1", value1, "2", value2);
-}
-
-void Writer::Write(const char* text, const string& value0, const string& value1,
-                   const string& value2, const string& value3) {
-  printer_->Print(text, "0", value0, "1", value1, "2", value2, "3", value3);
-}
-
-void Writer::WriteLine() {
-  printer_->Print(newline_);
-}
-
-void Writer::WriteLine(const char* text) {
-  Write(text);
-  WriteLine();
-}
-
-void Writer::WriteLine(const char* text, const string& value0) {
-  Write(text, value0);
-  WriteLine();
-}
-
-void Writer::WriteLine(const char* text, const string& value0,
-                       const string& value1) {
-  Write(text, value0, value1);
-  WriteLine();
-}
-
-void Writer::WriteLine(const char* text, const string& value0,
-                       const string& value1, const string& value2) {
-  Write(text, value0, value1, value2);
-  WriteLine();
-}
-
-void Writer::WriteLine(const char* text, const string& value0,
-                       const string& value1, const string& value2,
-                       const string& value3) {
-  Write(text, value0, value1, value2, value3);
-  WriteLine();
-}
-
-}  // namespace java
-}  // namespace compiler
-}  // namespace protobuf
-}  // namespace google
diff --git a/src/google/protobuf/compiler/java/java_map_field.cc b/src/google/protobuf/compiler/java/java_map_field.cc
index f25970e5..44b86cd7 100644
--- a/src/google/protobuf/compiler/java/java_map_field.cc
+++ b/src/google/protobuf/compiler/java/java_map_field.cc
@@ -156,9 +156,7 @@ ImmutableMapFieldGenerator(const FieldDescriptor* descriptor,
                                        int messageBitIndex,
                                        int builderBitIndex,
                                        Context* context)
-  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
-    builderBitIndex_(builderBitIndex), context_(context),
-    name_resolver_(context->GetNameResolver())  {
+  : descriptor_(descriptor), name_resolver_(context->GetNameResolver())  {
   SetMessageVariables(descriptor, messageBitIndex, builderBitIndex,
                       context->GetFieldGeneratorInfo(descriptor),
                       name_resolver_, &variables_);
diff --git a/src/google/protobuf/compiler/java/java_map_field.h b/src/google/protobuf/compiler/java/java_map_field.h
index 80a94f45..f2768f3a 100644
--- a/src/google/protobuf/compiler/java/java_map_field.h
+++ b/src/google/protobuf/compiler/java/java_map_field.h
@@ -68,9 +68,6 @@ class ImmutableMapFieldGenerator : public ImmutableFieldGenerator {
  private:
   const FieldDescriptor* descriptor_;
   map<string, string> variables_;
-  const int messageBitIndex_;
-  const int builderBitIndex_;
-  Context* context_;
   ClassNameResolver* name_resolver_;
 };
 
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 ccc1b32e..cd1698f0 100644
--- a/src/google/protobuf/compiler/java/java_map_field_lite.cc
+++ b/src/google/protobuf/compiler/java/java_map_field_lite.cc
@@ -139,9 +139,7 @@ ImmutableMapFieldLiteGenerator(const FieldDescriptor* descriptor,
                                        int messageBitIndex,
                                        int builderBitIndex,
                                        Context* context)
-  : descriptor_(descriptor), messageBitIndex_(messageBitIndex),
-    builderBitIndex_(builderBitIndex), context_(context),
-    name_resolver_(context->GetNameResolver())  {
+  : descriptor_(descriptor), name_resolver_(context->GetNameResolver())  {
   SetMessageVariables(descriptor, messageBitIndex, builderBitIndex,
                       context->GetFieldGeneratorInfo(descriptor),
                       name_resolver_, &variables_);
diff --git a/src/google/protobuf/compiler/java/java_map_field_lite.h b/src/google/protobuf/compiler/java/java_map_field_lite.h
index 82472602..a09cd536 100644
--- a/src/google/protobuf/compiler/java/java_map_field_lite.h
+++ b/src/google/protobuf/compiler/java/java_map_field_lite.h
@@ -67,9 +67,6 @@ class ImmutableMapFieldLiteGenerator : public ImmutableFieldLiteGenerator {
  private:
   const FieldDescriptor* descriptor_;
   map<string, string> variables_;
-  const int messageBitIndex_;
-  const int builderBitIndex_;
-  Context* context_;
   ClassNameResolver* name_resolver_;
 };
 
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index d2070bc4..5e7eeaa7 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -755,10 +755,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fdescriptor_2eproto() {
     "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(\tBh\n\023com.google.prot"
+    "tached_comments\030\006 \003(\tB[\n\023com.google.prot"
     "obufB\020DescriptorProtosH\001Z\ndescriptor\242\002\003G"
-    "PB\252\002\'Google.ProtocolBuffers.DescriptorPr"
-    "otos\260\002\001", 5007);
+    "PB\252\002\032Google.Protobuf.Reflection\260\002\001", 4994);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/descriptor.proto", &protobuf_RegisterTypes);
   FileDescriptorSet::default_instance_ = new FileDescriptorSet();
diff --git a/src/google/protobuf/descriptor.proto b/src/google/protobuf/descriptor.proto
index b70b385b..9d3dd8fb 100644
--- a/src/google/protobuf/descriptor.proto
+++ b/src/google/protobuf/descriptor.proto
@@ -44,7 +44,7 @@ option go_package = "descriptor";
 option java_package = "com.google.protobuf";
 option javanano_use_deprecated_package = true;
 option java_outer_classname = "DescriptorProtos";
-option csharp_namespace = "Google.ProtocolBuffers.DescriptorProtos";
+option csharp_namespace = "Google.Protobuf.Reflection";
 option objc_class_prefix = "GPB";
 
 // descriptor.proto must be optimized for speed because reflection-based
diff --git a/src/google/protobuf/duration.pb.cc b/src/google/protobuf/duration.pb.cc
index f78fce21..2e22ccb1 100644
--- a/src/google/protobuf/duration.pb.cc
+++ b/src/google/protobuf/duration.pb.cc
@@ -82,9 +82,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fduration_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\036google/protobuf/duration.proto\022\017google"
     ".protobuf\"*\n\010Duration\022\017\n\007seconds\030\001 \001(\003\022\r"
-    "\n\005nanos\030\002 \001(\005BH\n\023com.google.protobufB\rDu"
-    "rationProtoP\001\240\001\001\242\002\003GPB\252\002\026Google.Protocol"
-    "Buffersb\006proto3", 175);
+    "\n\005nanos\030\002 \001(\005BP\n\023com.google.protobufB\rDu"
+    "rationProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Protobuf"
+    ".WellKnownTypesb\006proto3", 183);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/duration.proto", &protobuf_RegisterTypes);
   Duration::default_instance_ = new Duration();
diff --git a/src/google/protobuf/duration.proto b/src/google/protobuf/duration.proto
index e466341a..0762c3c2 100644
--- a/src/google/protobuf/duration.proto
+++ b/src/google/protobuf/duration.proto
@@ -35,7 +35,7 @@ option java_generate_equals_and_hash = true;
 option java_multiple_files = true;
 option java_outer_classname = "DurationProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 // A Duration represents a signed, fixed-length span of time represented
diff --git a/src/google/protobuf/empty.pb.cc b/src/google/protobuf/empty.pb.cc
index 1a9a6661..1e1c2c8c 100644
--- a/src/google/protobuf/empty.pb.cc
+++ b/src/google/protobuf/empty.pb.cc
@@ -79,8 +79,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fempty_2eproto() {
 
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\033google/protobuf/empty.proto\022\017google.pr"
-    "otobuf\"\007\n\005EmptyB)\n\023com.google.protobufB\n"
-    "EmptyProtoP\001\242\002\003GPBb\006proto3", 106);
+    "otobuf\"\007\n\005EmptyBJ\n\023com.google.protobufB\n"
+    "EmptyProtoP\001\242\002\003GPB\252\002\036Google.Protobuf.Wel"
+    "lKnownTypesb\006proto3", 139);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/empty.proto", &protobuf_RegisterTypes);
   Empty::default_instance_ = new Empty();
diff --git a/src/google/protobuf/empty.proto b/src/google/protobuf/empty.proto
index 94df0397..363ec175 100644
--- a/src/google/protobuf/empty.proto
+++ b/src/google/protobuf/empty.proto
@@ -34,6 +34,7 @@ package google.protobuf;
 option java_multiple_files = true;
 option java_outer_classname = "EmptyProto";
 option java_package = "com.google.protobuf";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/field_mask.pb.cc b/src/google/protobuf/field_mask.pb.cc
index 68314fd3..88020ef2 100644
--- a/src/google/protobuf/field_mask.pb.cc
+++ b/src/google/protobuf/field_mask.pb.cc
@@ -81,8 +81,9 @@ void protobuf_AddDesc_google_2fprotobuf_2ffield_5fmask_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n google/protobuf/field_mask.proto\022\017goog"
     "le.protobuf\"\032\n\tFieldMask\022\r\n\005paths\030\001 \003(\tB"
-    "F\n\023com.google.protobufB\016FieldMaskProtoP\001"
-    "\242\002\003GPB\252\002\026Google.ProtocolBuffersb\006proto3", 159);
+    "N\n\023com.google.protobufB\016FieldMaskProtoP\001"
+    "\242\002\003GPB\252\002\036Google.Protobuf.WellKnownTypesb"
+    "\006proto3", 167);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/field_mask.proto", &protobuf_RegisterTypes);
   FieldMask::default_instance_ = new FieldMask();
diff --git a/src/google/protobuf/field_mask.proto b/src/google/protobuf/field_mask.proto
index 35b1acc3..c19f4410 100644
--- a/src/google/protobuf/field_mask.proto
+++ b/src/google/protobuf/field_mask.proto
@@ -34,7 +34,7 @@ package google.protobuf;
 option java_multiple_files = true;
 option java_outer_classname = "FieldMaskProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/io/coded_stream.h b/src/google/protobuf/io/coded_stream.h
index 961c1a3f..ad351dc3 100644
--- a/src/google/protobuf/io/coded_stream.h
+++ b/src/google/protobuf/io/coded_stream.h
@@ -112,8 +112,8 @@
 #include <string>
 #include <utility>
 #ifdef _MSC_VER
-  #if defined(_M_IX86) && \
-      !defined(PROTOBUF_DISABLE_LITTLE_ENDIAN_OPT_FOR_TEST)
+  // Assuming windows is always little-endian.
+  #if !defined(PROTOBUF_DISABLE_LITTLE_ENDIAN_OPT_FOR_TEST)
     #define PROTOBUF_LITTLE_ENDIAN 1
   #endif
   #if _MSC_VER >= 1300
diff --git a/src/google/protobuf/map.h b/src/google/protobuf/map.h
index 163ce9dc..d928b7a7 100644
--- a/src/google/protobuf/map.h
+++ b/src/google/protobuf/map.h
@@ -172,7 +172,7 @@ class Map {
     !defined(GOOGLE_PROTOBUF_OS_NACL) && !defined(GOOGLE_PROTOBUF_OS_ANDROID)
     template<class NodeType, class... Args>
     void construct(NodeType* p, Args&&... args) {
-      new (p) NodeType(std::forward<Args>(args)...);
+      new ((void*)p) NodeType(std::forward<Args>(args)...);
     }
 
     template<class NodeType>
diff --git a/src/google/protobuf/map_entry_lite.h b/src/google/protobuf/map_entry_lite.h
index 8de11766..52746da5 100644
--- a/src/google/protobuf/map_entry_lite.h
+++ b/src/google/protobuf/map_entry_lite.h
@@ -162,19 +162,7 @@ class MapEntryLite : public MessageLite {
           if (!KeyWireHandler::Read(input, mutable_key())) return false;
           set_has_key();
           if (!input->ExpectTag(kValueTag)) break;
-          // BEGIN GOOGLE LOCAL MODIFICATION
-          //   Add __has_cpp_attribute and NaCl and Emscripten checks.
-#if defined(__clang__) && defined(__has_cpp_attribute) \
-    && !defined(GOOGLE_PROTOBUF_OS_APPLE)
-#if defined(GOOGLE_PROTOBUF_OS_NACL) || defined(EMSCRIPTEN)
-          [[clang::fallthrough]];
-#elif __has_cpp_attribute(clang::fallthrough)
-          [[clang::fallthrough]];
-#endif
-#else
           GOOGLE_FALLTHROUGH_INTENDED;
-#endif
-          // END GOOGLE LOCAL MODIFICATION
 
         case kValueTag:
           if (!ValueWireHandler::Read(input, mutable_value())) return false;
diff --git a/src/google/protobuf/map_lite_unittest.proto b/src/google/protobuf/map_lite_unittest.proto
index febfe5f6..c69e8d94 100644
--- a/src/google/protobuf/map_lite_unittest.proto
+++ b/src/google/protobuf/map_lite_unittest.proto
@@ -32,7 +32,6 @@ syntax = "proto2";
 
 option cc_enable_arenas = true;
 option optimize_for = LITE_RUNTIME;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 import "google/protobuf/unittest_lite.proto";
 
diff --git a/src/google/protobuf/map_proto2_unittest.proto b/src/google/protobuf/map_proto2_unittest.proto
index 04ca6170..3d4af28e 100644
--- a/src/google/protobuf/map_proto2_unittest.proto
+++ b/src/google/protobuf/map_proto2_unittest.proto
@@ -36,8 +36,6 @@ syntax = "proto2";
 // In map_test_util.h we do "using namespace unittest = protobuf_unittest".
 package protobuf_unittest;
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
-
 enum Proto2MapEnum {
   PROTO2_MAP_ENUM_FOO   = 0;
   PROTO2_MAP_ENUM_BAR   = 1;
diff --git a/src/google/protobuf/map_unittest.proto b/src/google/protobuf/map_unittest.proto
index cbf747d9..b308c7ff 100644
--- a/src/google/protobuf/map_unittest.proto
+++ b/src/google/protobuf/map_unittest.proto
@@ -31,7 +31,6 @@
 syntax = "proto3";
 
 option cc_enable_arenas = true;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 import "google/protobuf/unittest.proto";
 
diff --git a/src/google/protobuf/map_unittest_proto3.proto b/src/google/protobuf/map_unittest_proto3.proto
new file mode 100644
index 00000000..16be2773
--- /dev/null
+++ b/src/google/protobuf/map_unittest_proto3.proto
@@ -0,0 +1,120 @@
+// 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.
+
+// This file is mostly equivalent to map_unittest.proto, but imports
+// unittest_proto3.proto instead of unittest.proto, so that it only
+// uses proto3 messages. This makes it suitable for testing
+// implementations which only support proto3.
+// The TestRequiredMessageMap message has been removed as there are no
+// required fields in proto3.
+syntax = "proto3";
+
+option cc_enable_arenas = true;
+option csharp_namespace = "Google.Protobuf.TestProtos";
+
+import "google/protobuf/unittest_proto3.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".
+package protobuf_unittest;
+
+// Tests maps.
+message TestMap {
+  map<int32   , int32   > map_int32_int32       = 1;
+  map<int64   , int64   > map_int64_int64       = 2;
+  map<uint32  , uint32  > map_uint32_uint32     = 3;
+  map<uint64  , uint64  > map_uint64_uint64     = 4;
+  map<sint32  , sint32  > map_sint32_sint32     = 5;
+  map<sint64  , sint64  > map_sint64_sint64     = 6;
+  map<fixed32 , fixed32 > map_fixed32_fixed32   = 7;
+  map<fixed64 , fixed64 > map_fixed64_fixed64   = 8;
+  map<sfixed32, sfixed32> map_sfixed32_sfixed32 = 9;
+  map<sfixed64, sfixed64> map_sfixed64_sfixed64 = 10;
+  map<int32   , float   > map_int32_float       = 11;
+  map<int32   , double  > map_int32_double      = 12;
+  map<bool    , bool    > map_bool_bool         = 13;
+  map<string  , string  > map_string_string     = 14;
+  map<int32   , bytes   > map_int32_bytes       = 15;
+  map<int32   , MapEnum > map_int32_enum        = 16;
+  map<int32   , ForeignMessage> map_int32_foreign_message = 17;
+}
+
+message TestMapSubmessage {
+  TestMap test_map = 1;
+}
+
+message TestMessageMap {
+  map<int32, TestAllTypes> map_int32_message = 1;
+}
+
+// Two map fields share the same entry default instance.
+message TestSameTypeMap {
+  map<int32, int32> map1 = 1;
+  map<int32, int32> map2 = 2;
+}
+
+enum MapEnum {
+  MAP_ENUM_FOO = 0;
+  MAP_ENUM_BAR = 1;
+  MAP_ENUM_BAZ = 2;
+}
+
+message TestArenaMap {
+  map<int32   , int32   > map_int32_int32       = 1;
+  map<int64   , int64   > map_int64_int64       = 2;
+  map<uint32  , uint32  > map_uint32_uint32     = 3;
+  map<uint64  , uint64  > map_uint64_uint64     = 4;
+  map<sint32  , sint32  > map_sint32_sint32     = 5;
+  map<sint64  , sint64  > map_sint64_sint64     = 6;
+  map<fixed32 , fixed32 > map_fixed32_fixed32   = 7;
+  map<fixed64 , fixed64 > map_fixed64_fixed64   = 8;
+  map<sfixed32, sfixed32> map_sfixed32_sfixed32 = 9;
+  map<sfixed64, sfixed64> map_sfixed64_sfixed64 = 10;
+  map<int32   , float   > map_int32_float       = 11;
+  map<int32   , double  > map_int32_double      = 12;
+  map<bool    , bool    > map_bool_bool         = 13;
+  map<int32   , MapEnum > map_int32_enum        = 14;
+  map<int32   , ForeignMessage> map_int32_foreign_message = 15;
+}
+
+// Previously, message containing enum called Type cannot be used as value of
+// map field.
+message MessageContainingEnumCalledType {
+  enum Type {
+    TYPE_FOO = 0;
+  }
+  map<int32, MessageContainingEnumCalledType> type = 1;
+}
+
+// Previously, message cannot contain map field called "entry".
+message MessageContainingMapCalledEntry {
+  map<int32, int32> entry = 1;
+}
diff --git a/src/google/protobuf/source_context.pb.cc b/src/google/protobuf/source_context.pb.cc
index 3b3799a9..5c88363f 100644
--- a/src/google/protobuf/source_context.pb.cc
+++ b/src/google/protobuf/source_context.pb.cc
@@ -81,8 +81,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fsource_5fcontext_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n$google/protobuf/source_context.proto\022\017"
     "google.protobuf\"\"\n\rSourceContext\022\021\n\tfile"
-    "_name\030\001 \001(\tB1\n\023com.google.protobufB\022Sour"
-    "ceContextProtoP\001\242\002\003GPBb\006proto3", 150);
+    "_name\030\001 \001(\tBR\n\023com.google.protobufB\022Sour"
+    "ceContextProtoP\001\242\002\003GPB\252\002\036Google.Protobuf"
+    ".WellKnownTypesb\006proto3", 183);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/source_context.proto", &protobuf_RegisterTypes);
   SourceContext::default_instance_ = new SourceContext();
diff --git a/src/google/protobuf/source_context.proto b/src/google/protobuf/source_context.proto
index 2c8a17a8..98d4920a 100644
--- a/src/google/protobuf/source_context.proto
+++ b/src/google/protobuf/source_context.proto
@@ -34,6 +34,7 @@ package google.protobuf;
 option java_multiple_files = true;
 option java_outer_classname = "SourceContextProto";
 option java_package = "com.google.protobuf";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/struct.pb.cc b/src/google/protobuf/struct.pb.cc
index 30113cdb..a7e2eafd 100644
--- a/src/google/protobuf/struct.pb.cc
+++ b/src/google/protobuf/struct.pb.cc
@@ -165,9 +165,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fstruct_2eproto() {
     "\000\0220\n\nlist_value\030\006 \001(\0132\032.google.protobuf."
     "ListValueH\000B\006\n\004kind\"3\n\tListValue\022&\n\006valu"
     "es\030\001 \003(\0132\026.google.protobuf.Value*\033\n\tNull"
-    "Value\022\016\n\nNULL_VALUE\020\000BF\n\023com.google.prot"
-    "obufB\013StructProtoP\001\240\001\001\242\002\003GPB\252\002\026Google.Pr"
-    "otocolBuffersb\006proto3", 581);
+    "Value\022\016\n\nNULL_VALUE\020\000BN\n\023com.google.prot"
+    "obufB\013StructProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Pr"
+    "otobuf.WellKnownTypesb\006proto3", 589);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/struct.proto", &protobuf_RegisterTypes);
   Struct::default_instance_ = new Struct();
diff --git a/src/google/protobuf/struct.proto b/src/google/protobuf/struct.proto
index cd102731..4ff10cd0 100644
--- a/src/google/protobuf/struct.proto
+++ b/src/google/protobuf/struct.proto
@@ -35,7 +35,7 @@ option java_generate_equals_and_hash = true;
 option java_multiple_files = true;
 option java_outer_classname = "StructProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/stubs/mutex.h b/src/google/protobuf/stubs/mutex.h
index 2cce0561..7ef1cb69 100644
--- a/src/google/protobuf/stubs/mutex.h
+++ b/src/google/protobuf/stubs/mutex.h
@@ -30,6 +30,10 @@
 #ifndef GOOGLE_PROTOBUF_STUBS_MUTEX_H_
 #define GOOGLE_PROTOBUF_STUBS_MUTEX_H_
 
+#ifdef GOOGLE_PROTOBUF_NO_THREADLOCAL
+#include <pthread.h>
+#endif
+
 #include <google/protobuf/stubs/macros.h>
 
 // ===================================================================
diff --git a/src/google/protobuf/stubs/port.h b/src/google/protobuf/stubs/port.h
index c86cf35b..8a5d1a13 100644
--- a/src/google/protobuf/stubs/port.h
+++ b/src/google/protobuf/stubs/port.h
@@ -204,8 +204,19 @@ static const uint64 kuint64max = GOOGLE_ULONGLONG(0xFFFFFFFFFFFFFFFF);
 #define GOOGLE_SAFE_CONCURRENT_WRITES_END()
 #endif
 
+#if defined(__clang__) && defined(__has_cpp_attribute) \
+    && !defined(GOOGLE_PROTOBUF_OS_APPLE)
+# if defined(GOOGLE_PROTOBUF_OS_NACL) || defined(EMSCRIPTEN) || \
+     __has_cpp_attribute(clang::fallthrough)
+#  define GOOGLE_FALLTHROUGH_INTENDED [[clang::fallthrough]]
+# endif
+#endif
+
+#ifndef GOOGLE_FALLTHROUGH_INTENDED
+# define GOOGLE_FALLTHROUGH_INTENDED
+#endif
+
 #define GOOGLE_GUARDED_BY(x)
-#define GOOGLE_FALLTHROUGH_INTENDED
 #define GOOGLE_ATTRIBUTE_COLD
 
 // x86 and x86-64 can perform unaligned loads/stores directly.
diff --git a/src/google/protobuf/timestamp.pb.cc b/src/google/protobuf/timestamp.pb.cc
index 877dc8f3..2ee0ec29 100644
--- a/src/google/protobuf/timestamp.pb.cc
+++ b/src/google/protobuf/timestamp.pb.cc
@@ -82,9 +82,9 @@ void protobuf_AddDesc_google_2fprotobuf_2ftimestamp_2eproto() {
   ::google::protobuf::DescriptorPool::InternalAddGeneratedFile(
     "\n\037google/protobuf/timestamp.proto\022\017googl"
     "e.protobuf\"+\n\tTimestamp\022\017\n\007seconds\030\001 \001(\003"
-    "\022\r\n\005nanos\030\002 \001(\005BI\n\023com.google.protobufB\016"
-    "TimestampProtoP\001\240\001\001\242\002\003GPB\252\002\026Google.Proto"
-    "colBuffersb\006proto3", 178);
+    "\022\r\n\005nanos\030\002 \001(\005BQ\n\023com.google.protobufB\016"
+    "TimestampProtoP\001\240\001\001\242\002\003GPB\252\002\036Google.Proto"
+    "buf.WellKnownTypesb\006proto3", 186);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/timestamp.proto", &protobuf_RegisterTypes);
   Timestamp::default_instance_ = new Timestamp();
diff --git a/src/google/protobuf/timestamp.proto b/src/google/protobuf/timestamp.proto
index 381ff997..11f258da 100644
--- a/src/google/protobuf/timestamp.proto
+++ b/src/google/protobuf/timestamp.proto
@@ -35,7 +35,7 @@ option java_generate_equals_and_hash = true;
 option java_multiple_files = true;
 option java_outer_classname = "TimestampProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/type.pb.cc b/src/google/protobuf/type.pb.cc
index 8b08909e..029a72c6 100644
--- a/src/google/protobuf/type.pb.cc
+++ b/src/google/protobuf/type.pb.cc
@@ -221,9 +221,9 @@ void protobuf_AddDesc_google_2fprotobuf_2ftype_2eproto() {
     "ntext\"S\n\tEnumValue\022\014\n\004name\030\001 \001(\t\022\016\n\006numb"
     "er\030\002 \001(\005\022(\n\007options\030\003 \003(\0132\027.google.proto"
     "buf.Option\";\n\006Option\022\014\n\004name\030\001 \001(\t\022#\n\005va"
-    "lue\030\002 \001(\0132\024.google.protobuf.AnyB(\n\023com.g"
-    "oogle.protobufB\tTypeProtoP\001\242\002\003GPBb\006proto"
-    "3", 1321);
+    "lue\030\002 \001(\0132\024.google.protobuf.AnyBI\n\023com.g"
+    "oogle.protobufB\tTypeProtoP\001\242\002\003GPB\252\002\036Goog"
+    "le.Protobuf.WellKnownTypesb\006proto3", 1354);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/type.proto", &protobuf_RegisterTypes);
   Type::default_instance_ = new Type();
diff --git a/src/google/protobuf/type.proto b/src/google/protobuf/type.proto
index ace5d995..ce22d33d 100644
--- a/src/google/protobuf/type.proto
+++ b/src/google/protobuf/type.proto
@@ -37,6 +37,7 @@ import "google/protobuf/source_context.proto";
 option java_multiple_files = true;
 option java_outer_classname = "TypeProto";
 option java_package = "com.google.protobuf";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";
 
 
diff --git a/src/google/protobuf/unittest.proto b/src/google/protobuf/unittest.proto
index 834c9b56..85fe6153 100644
--- a/src/google/protobuf/unittest.proto
+++ b/src/google/protobuf/unittest.proto
@@ -42,7 +42,6 @@ option cc_generic_services = true;     // auto-added
 option java_generic_services = true;   // auto-added
 option py_generic_services = true;     // auto-added
 option cc_enable_arenas = true;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 import "google/protobuf/unittest_import.proto";
 
diff --git a/src/google/protobuf/unittest_custom_options.proto b/src/google/protobuf/unittest_custom_options.proto
index 8f9fb582..d4d6e869 100644
--- a/src/google/protobuf/unittest_custom_options.proto
+++ b/src/google/protobuf/unittest_custom_options.proto
@@ -41,7 +41,6 @@ syntax = "proto2";
 option cc_generic_services = true;     // auto-added
 option java_generic_services = true;   // auto-added
 option py_generic_services = true;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 // A custom file option (defined below).
 option (file_opt1) = 9876543210;
diff --git a/src/google/protobuf/unittest_drop_unknown_fields.proto b/src/google/protobuf/unittest_drop_unknown_fields.proto
index faaddc6e..8aa3a37b 100644
--- a/src/google/protobuf/unittest_drop_unknown_fields.proto
+++ b/src/google/protobuf/unittest_drop_unknown_fields.proto
@@ -33,7 +33,7 @@ syntax = "proto3";
 package unittest_drop_unknown_fields;
 option objc_class_prefix = "DropUnknowns";
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
+option csharp_namespace = "Google.Protobuf.TestProtos";
 
 message Foo {
   enum NestedEnum {
diff --git a/src/google/protobuf/unittest_embed_optimize_for.proto b/src/google/protobuf/unittest_embed_optimize_for.proto
index c4ccccb7..d8b0f9b9 100644
--- a/src/google/protobuf/unittest_embed_optimize_for.proto
+++ b/src/google/protobuf/unittest_embed_optimize_for.proto
@@ -39,8 +39,6 @@ import "google/protobuf/unittest_optimize_for.proto";
 
 package protobuf_unittest;
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
-
 // We optimize for speed here, but we are importing a proto that is optimized
 // for code size.
 option optimize_for = SPEED;
diff --git a/src/google/protobuf/unittest_enormous_descriptor.proto b/src/google/protobuf/unittest_enormous_descriptor.proto
index f8fcc9c0..6e65dc18 100644
--- a/src/google/protobuf/unittest_enormous_descriptor.proto
+++ b/src/google/protobuf/unittest_enormous_descriptor.proto
@@ -40,7 +40,6 @@ syntax = "proto2";
 
 package google.protobuf;
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 // Avoid generating insanely long methods.
 option optimize_for = CODE_SIZE;
diff --git a/src/google/protobuf/unittest_import.proto b/src/google/protobuf/unittest_import.proto
index ae2e90b8..7e165220 100644
--- a/src/google/protobuf/unittest_import.proto
+++ b/src/google/protobuf/unittest_import.proto
@@ -47,7 +47,6 @@ option cc_enable_arenas = true;
 
 // Exercise the java_package option.
 option java_package = "com.google.protobuf.test";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 // Do not set a java_outer_classname here to verify that Proto2 works without
 // one.
diff --git a/src/google/protobuf/unittest_import_lite.proto b/src/google/protobuf/unittest_import_lite.proto
index ca208582..a7afa452 100644
--- a/src/google/protobuf/unittest_import_lite.proto
+++ b/src/google/protobuf/unittest_import_lite.proto
@@ -38,7 +38,6 @@ package protobuf_unittest_import;
 option optimize_for = LITE_RUNTIME;
 
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 import public "google/protobuf/unittest_import_public_lite.proto";
 
diff --git a/src/google/protobuf/unittest_import_proto3.proto b/src/google/protobuf/unittest_import_proto3.proto
new file mode 100644
index 00000000..59673eaf
--- /dev/null
+++ b/src/google/protobuf/unittest_import_proto3.proto
@@ -0,0 +1,68 @@
+// 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.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// A proto file which is imported by unittest_proto3.proto to test importing.
+
+syntax = "proto3";
+
+// 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 test_util.h we do
+// "using namespace unittest_import = protobuf_unittest_import".
+package protobuf_unittest_import;
+
+option optimize_for = SPEED;
+option cc_enable_arenas = true;
+
+// Exercise the java_package option.
+option java_package = "com.google.protobuf.test";
+option csharp_namespace = "Google.Protobuf.TestProtos";
+
+// Do not set a java_outer_classname here to verify that Proto2 works without
+// one.
+
+// Test public import
+import public "google/protobuf/unittest_import_public_proto3.proto";
+
+message ImportMessage {
+  int32 d = 1;
+}
+
+enum ImportEnum {
+  IMPORT_ENUM_UNSPECIFIED = 0;
+  IMPORT_FOO = 7;
+  IMPORT_BAR = 8;
+  IMPORT_BAZ = 9;
+}
+
diff --git a/src/google/protobuf/unittest_import_public.proto b/src/google/protobuf/unittest_import_public.proto
index 0bc5d617..ffaf7736 100644
--- a/src/google/protobuf/unittest_import_public.proto
+++ b/src/google/protobuf/unittest_import_public.proto
@@ -35,7 +35,6 @@ syntax = "proto2";
 package protobuf_unittest_import;
 
 option java_package = "com.google.protobuf.test";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 message PublicImportMessage {
   optional int32 e = 1;
diff --git a/src/google/protobuf/unittest_import_public_lite.proto b/src/google/protobuf/unittest_import_public_lite.proto
index 231ab9dd..33549c22 100644
--- a/src/google/protobuf/unittest_import_public_lite.proto
+++ b/src/google/protobuf/unittest_import_public_lite.proto
@@ -37,7 +37,6 @@ package protobuf_unittest_import;
 option optimize_for = LITE_RUNTIME;
 
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 message PublicImportMessageLite {
   optional int32 e = 1;
diff --git a/src/google/protobuf/unittest_import_public_proto3.proto b/src/google/protobuf/unittest_import_public_proto3.proto
new file mode 100644
index 00000000..d6f11e28
--- /dev/null
+++ b/src/google/protobuf/unittest_import_public_proto3.proto
@@ -0,0 +1,42 @@
+// 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.
+
+// Author: liujisi@google.com (Pherl Liu)
+
+syntax = "proto3";
+
+package protobuf_unittest_import;
+
+option java_package = "com.google.protobuf.test";
+option csharp_namespace = "Google.Protobuf.TestProtos";
+
+message PublicImportMessage {
+ int32 e = 1;
+}
diff --git a/src/google/protobuf/unittest_lite.proto b/src/google/protobuf/unittest_lite.proto
index 0040874b..662c0e46 100644
--- a/src/google/protobuf/unittest_lite.proto
+++ b/src/google/protobuf/unittest_lite.proto
@@ -40,7 +40,6 @@ import "google/protobuf/unittest_import_lite.proto";
 option optimize_for = LITE_RUNTIME;
 
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 // Same as TestAllTypes but with the lite runtime.
 message TestAllTypesLite {
diff --git a/src/google/protobuf/unittest_lite_imports_nonlite.proto b/src/google/protobuf/unittest_lite_imports_nonlite.proto
index d955cc14..132d6a82 100644
--- a/src/google/protobuf/unittest_lite_imports_nonlite.proto
+++ b/src/google/protobuf/unittest_lite_imports_nonlite.proto
@@ -38,7 +38,6 @@ package protobuf_unittest;
 import "google/protobuf/unittest.proto";
 
 option optimize_for = LITE_RUNTIME;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 message TestLiteImportsNonlite {
   optional TestAllTypes message = 1;
diff --git a/src/google/protobuf/unittest_mset.proto b/src/google/protobuf/unittest_mset.proto
index 425c9a5a..3aa31fa9 100644
--- a/src/google/protobuf/unittest_mset.proto
+++ b/src/google/protobuf/unittest_mset.proto
@@ -39,7 +39,6 @@ package protobuf_unittest;
 
 option cc_enable_arenas = true;
 option optimize_for = SPEED;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 // A message with message_set_wire_format.
 message TestMessageSet {
diff --git a/src/google/protobuf/unittest_no_field_presence.proto b/src/google/protobuf/unittest_no_field_presence.proto
index f5cc4cc3..994afff4 100644
--- a/src/google/protobuf/unittest_no_field_presence.proto
+++ b/src/google/protobuf/unittest_no_field_presence.proto
@@ -37,8 +37,6 @@ import "google/protobuf/unittest.proto";
 
 package proto2_nofieldpresence_unittest;
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos.Proto3";
-
 // This proto includes every type of field in both singular and repeated
 // forms.
 message TestAllTypes {
diff --git a/src/google/protobuf/unittest_optimize_for.proto b/src/google/protobuf/unittest_optimize_for.proto
index 2bcd16e4..ee9cc7bd 100644
--- a/src/google/protobuf/unittest_optimize_for.proto
+++ b/src/google/protobuf/unittest_optimize_for.proto
@@ -40,7 +40,6 @@ import "google/protobuf/unittest.proto";
 package protobuf_unittest;
 
 option optimize_for = CODE_SIZE;
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
 
 message TestOptimizedForSize {
   optional int32 i = 1;
diff --git a/src/google/protobuf/unittest_preserve_unknown_enum.proto b/src/google/protobuf/unittest_preserve_unknown_enum.proto
index abc3de28..2f91332c 100644
--- a/src/google/protobuf/unittest_preserve_unknown_enum.proto
+++ b/src/google/protobuf/unittest_preserve_unknown_enum.proto
@@ -33,7 +33,7 @@ syntax = "proto3";
 package proto3_preserve_unknown_enum_unittest;
 option objc_class_prefix = "UnknownEnums";
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
+option csharp_namespace = "Google.Protobuf.TestProtos";
 
 enum MyEnum {
   FOO = 0;
diff --git a/src/google/protobuf/unittest_preserve_unknown_enum2.proto b/src/google/protobuf/unittest_preserve_unknown_enum2.proto
index 168b2407..adf42968 100644
--- a/src/google/protobuf/unittest_preserve_unknown_enum2.proto
+++ b/src/google/protobuf/unittest_preserve_unknown_enum2.proto
@@ -32,8 +32,6 @@ syntax = "proto2";
 
 package proto2_preserve_unknown_enum_unittest;
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
-
 enum MyEnum {
   FOO = 0;
   BAR = 1;
diff --git a/src/google/protobuf/unittest_proto3.proto b/src/google/protobuf/unittest_proto3.proto
new file mode 100644
index 00000000..f59d2178
--- /dev/null
+++ b/src/google/protobuf/unittest_proto3.proto
@@ -0,0 +1,388 @@
+// 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.
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+//
+// A proto file we will use for unit testing.
+
+syntax = "proto3";
+
+// Some generic_services option(s) added automatically.
+// See:  http://go/proto2-generic-services-default
+option cc_generic_services = true;     // auto-added
+option java_generic_services = true;   // auto-added
+option py_generic_services = true;     // auto-added
+option cc_enable_arenas = true;
+option csharp_namespace = "Google.Protobuf.TestProtos";
+
+import "google/protobuf/unittest_import_proto3.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 test_util.h we do "using namespace unittest = protobuf_unittest".
+package protobuf_unittest;
+
+// Protos optimized for SPEED use a strict superset of the generated code
+// of equivalent ones optimized for CODE_SIZE, so we should optimize all our
+// tests for speed unless explicitly testing code size optimization.
+option optimize_for = SPEED;
+
+option java_outer_classname = "UnittestProto";
+
+// This proto includes every type of field in both singular and repeated
+// forms.
+message TestAllTypes {
+  message NestedMessage {
+    // The field name "b" fails to compile in proto1 because it conflicts with
+    // a local variable named "b" in one of the generated methods.  Doh.
+    // This file needs to compile in proto1 to test backwards-compatibility.
+    int32 bb = 1;
+  }
+
+  enum NestedEnum {
+    NESTED_ENUM_UNSPECIFIED = 0;
+    FOO = 1;
+    BAR = 2;
+    BAZ = 3;
+    NEG = -1;  // Intentionally negative.
+  }
+
+  // Singular
+  int32 single_int32 = 1;
+  int64 single_int64 = 2;
+  uint32 single_uint32 = 3;
+  uint64 single_uint64 = 4;
+  sint32 single_sint32 = 5;
+  sint64 single_sint64 = 6;
+  fixed32 single_fixed32 = 7;
+  fixed64 single_fixed64 = 8;
+  sfixed32 single_sfixed32 = 9;
+  sfixed64 single_sfixed64 = 10;
+  float single_float = 11;
+  double single_double = 12;
+  bool single_bool = 13;
+  string single_string = 14;
+  bytes single_bytes = 15;
+
+  NestedMessage single_nested_message = 18;
+  ForeignMessage single_foreign_message = 19;
+  protobuf_unittest_import.ImportMessage single_import_message = 20;
+
+  NestedEnum single_nested_enum = 21;
+  ForeignEnum single_foreign_enum = 22;
+  protobuf_unittest_import.ImportEnum single_import_enum = 23;
+
+  // Defined in unittest_import_public.proto
+  protobuf_unittest_import.PublicImportMessage
+      single_public_import_message = 26;
+
+  // Repeated
+  repeated    int32 repeated_int32    = 31;
+  repeated    int64 repeated_int64    = 32;
+  repeated   uint32 repeated_uint32   = 33;
+  repeated   uint64 repeated_uint64   = 34;
+  repeated   sint32 repeated_sint32   = 35;
+  repeated   sint64 repeated_sint64   = 36;
+  repeated  fixed32 repeated_fixed32  = 37;
+  repeated  fixed64 repeated_fixed64  = 38;
+  repeated sfixed32 repeated_sfixed32 = 39;
+  repeated sfixed64 repeated_sfixed64 = 40;
+  repeated    float repeated_float    = 41;
+  repeated   double repeated_double   = 42;
+  repeated     bool repeated_bool     = 43;
+  repeated   string repeated_string   = 44;
+  repeated    bytes repeated_bytes    = 45;
+
+  repeated NestedMessage                        repeated_nested_message  = 48;
+  repeated ForeignMessage                       repeated_foreign_message = 49;
+  repeated protobuf_unittest_import.ImportMessage repeated_import_message  = 50;
+
+  repeated NestedEnum                           repeated_nested_enum     = 51;
+  repeated ForeignEnum                          repeated_foreign_enum    = 52;
+  repeated protobuf_unittest_import.ImportEnum    repeated_import_enum     = 53;
+  // Defined in unittest_import_public.proto
+  repeated protobuf_unittest_import.PublicImportMessage
+      repeated_public_import_message = 54;
+
+  // For oneof test
+  oneof oneof_field {
+    uint32 oneof_uint32 = 111;
+    NestedMessage oneof_nested_message = 112;
+    string oneof_string = 113;
+    bytes oneof_bytes = 114;
+  }
+}
+
+// This proto includes a recusively nested message.
+message NestedTestAllTypes {
+  NestedTestAllTypes child = 1;
+  TestAllTypes payload = 2;
+  repeated NestedTestAllTypes repeated_child = 3;
+}
+
+message TestDeprecatedFields {
+  int32 deprecated_int32 = 1 [deprecated=true];
+}
+
+// Define these after TestAllTypes to make sure the compiler can handle
+// that.
+message ForeignMessage {
+  int32 c = 1;
+}
+
+enum ForeignEnum {
+  FOREIGN_UNSPECIFIED = 0;
+  FOREIGN_FOO = 4;
+  FOREIGN_BAR = 5;
+  FOREIGN_BAZ = 6;
+}
+
+message TestReservedFields {
+  reserved 2, 15, 9 to 11;
+  reserved "bar", "baz";
+}
+
+
+// Test that we can use NestedMessage from outside TestAllTypes.
+message TestForeignNested {
+  TestAllTypes.NestedMessage foreign_nested = 1;
+}
+
+// Test that really large tag numbers don't break anything.
+message TestReallyLargeTagNumber {
+  // The largest possible tag number is 2^28 - 1, since the wire format uses
+  // three bits to communicate wire type.
+  int32 a = 1;
+  int32 bb = 268435455;
+}
+
+message TestRecursiveMessage {
+  TestRecursiveMessage a = 1;
+  int32 i = 2;
+}
+
+// Test that mutual recursion works.
+message TestMutualRecursionA {
+  TestMutualRecursionB bb = 1;
+}
+
+message TestMutualRecursionB {
+  TestMutualRecursionA a = 1;
+  int32 optional_int32 = 2;
+}
+
+
+// Test an enum that has multiple values with the same number.
+enum TestEnumWithDupValue {
+  TEST_ENUM_WITH_DUP_VALUE_UNSPECIFIED = 0;
+  option allow_alias = true;
+
+  FOO1 = 1;
+  BAR1 = 2;
+  BAZ = 3;
+  FOO2 = 1;
+  BAR2 = 2;
+}
+
+// Test an enum with large, unordered values.
+enum TestSparseEnum {
+  TEST_SPARSE_ENUM_UNSPECIFIED = 0;
+  SPARSE_A = 123;
+  SPARSE_B = 62374;
+  SPARSE_C = 12589234;
+  SPARSE_D = -15;
+  SPARSE_E = -53452;
+  // In proto3, value 0 must be the first one specified
+  // SPARSE_F = 0;
+  SPARSE_G = 2;
+}
+
+// Test message with CamelCase field names.  This violates Protocol Buffer
+// standard style.
+message TestCamelCaseFieldNames {
+  int32 PrimitiveField = 1;
+  string StringField = 2;
+  ForeignEnum EnumField = 3;
+  ForeignMessage MessageField = 4;
+
+  repeated int32 RepeatedPrimitiveField = 7;
+  repeated string RepeatedStringField = 8;
+  repeated ForeignEnum RepeatedEnumField = 9;
+  repeated ForeignMessage RepeatedMessageField = 10;
+}
+
+
+// We list fields out of order, to ensure that we're using field number and not
+// field index to determine serialization order.
+message TestFieldOrderings {
+  string my_string = 11;
+  int64 my_int = 1;
+  float my_float = 101;
+  message NestedMessage {
+    int64 oo = 2;
+    // The field name "b" fails to compile in proto1 because it conflicts with
+    // a local variable named "b" in one of the generated methods.  Doh.
+    // This file needs to compile in proto1 to test backwards-compatibility.
+    int32 bb = 1;
+  }
+
+  NestedMessage single_nested_message  = 200;
+}
+
+message SparseEnumMessage {
+  TestSparseEnum sparse_enum = 1;
+}
+
+// Test String and Bytes: string is for valid UTF-8 strings
+message OneString {
+  string data = 1;
+}
+
+message MoreString {
+  repeated string data = 1;
+}
+
+message OneBytes {
+  bytes data = 1;
+}
+
+message MoreBytes {
+  bytes data = 1;
+}
+
+// Test int32, uint32, int64, uint64, and bool are all compatible
+message Int32Message {
+  int32 data = 1;
+}
+
+message Uint32Message {
+  uint32 data = 1;
+}
+
+message Int64Message {
+  int64 data = 1;
+}
+
+message Uint64Message {
+  uint64 data = 1;
+}
+
+message BoolMessage {
+  bool data = 1;
+}
+
+// Test oneofs.
+message TestOneof {
+  oneof foo {
+    int32 foo_int = 1;
+    string foo_string = 2;
+    TestAllTypes foo_message = 3;
+  }
+}
+
+// Test messages for packed fields
+
+message TestPackedTypes {
+  repeated    int32 packed_int32    =  90 [packed = true];
+  repeated    int64 packed_int64    =  91 [packed = true];
+  repeated   uint32 packed_uint32   =  92 [packed = true];
+  repeated   uint64 packed_uint64   =  93 [packed = true];
+  repeated   sint32 packed_sint32   =  94 [packed = true];
+  repeated   sint64 packed_sint64   =  95 [packed = true];
+  repeated  fixed32 packed_fixed32  =  96 [packed = true];
+  repeated  fixed64 packed_fixed64  =  97 [packed = true];
+  repeated sfixed32 packed_sfixed32 =  98 [packed = true];
+  repeated sfixed64 packed_sfixed64 =  99 [packed = true];
+  repeated    float packed_float    = 100 [packed = true];
+  repeated   double packed_double   = 101 [packed = true];
+  repeated     bool packed_bool     = 102 [packed = true];
+  repeated ForeignEnum packed_enum  = 103 [packed = true];
+}
+
+// A message with the same fields as TestPackedTypes, but without packing. Used
+// to test packed <-> unpacked wire compatibility.
+message TestUnpackedTypes {
+  repeated    int32 unpacked_int32    =  90 [packed = false];
+  repeated    int64 unpacked_int64    =  91 [packed = false];
+  repeated   uint32 unpacked_uint32   =  92 [packed = false];
+  repeated   uint64 unpacked_uint64   =  93 [packed = false];
+  repeated   sint32 unpacked_sint32   =  94 [packed = false];
+  repeated   sint64 unpacked_sint64   =  95 [packed = false];
+  repeated  fixed32 unpacked_fixed32  =  96 [packed = false];
+  repeated  fixed64 unpacked_fixed64  =  97 [packed = false];
+  repeated sfixed32 unpacked_sfixed32 =  98 [packed = false];
+  repeated sfixed64 unpacked_sfixed64 =  99 [packed = false];
+  repeated    float unpacked_float    = 100 [packed = false];
+  repeated   double unpacked_double   = 101 [packed = false];
+  repeated     bool unpacked_bool     = 102 [packed = false];
+  repeated ForeignEnum unpacked_enum  = 103 [packed = false];
+}
+
+message TestRepeatedScalarDifferentTagSizes {
+  // Parsing repeated fixed size values used to fail. This message needs to be
+  // used in order to get a tag of the right size; all of the repeated fields
+  // in TestAllTypes didn't trigger the check.
+  repeated fixed32 repeated_fixed32 = 12;
+  // Check for a varint type, just for good measure.
+  repeated int32   repeated_int32   = 13;
+
+  // These have two-byte tags.
+  repeated fixed64 repeated_fixed64 = 2046;
+  repeated int64   repeated_int64   = 2047;
+
+  // Three byte tags.
+  repeated float   repeated_float   = 262142;
+  repeated uint64  repeated_uint64  = 262143;
+}
+
+message TestCommentInjectionMessage {
+  // */ <- This should not close the generated doc comment
+  string a = 1;
+}
+
+
+// Test that RPC services work.
+message FooRequest  {}
+message FooResponse {}
+
+message FooClientMessage {}
+message FooServerMessage{}
+
+service TestService {
+  rpc Foo(FooRequest) returns (FooResponse);
+  rpc Bar(BarRequest) returns (BarResponse);
+}
+
+
+message BarRequest  {}
+message BarResponse {}
+
diff --git a/src/google/protobuf/unittest_well_known_types.proto b/src/google/protobuf/unittest_well_known_types.proto
index e157260e..2cb7775c 100644
--- a/src/google/protobuf/unittest_well_known_types.proto
+++ b/src/google/protobuf/unittest_well_known_types.proto
@@ -2,6 +2,7 @@ syntax = "proto3";
 
 package protobuf_unittest;
 
+option csharp_namespace = "Google.Protobuf.TestProtos";
 option java_multiple_files = true;
 option java_package = "com.google.protobuf.test";
 
@@ -17,6 +18,8 @@ import "google/protobuf/type.proto";
 import "google/protobuf/wrappers.proto";
 
 // Test that we can include all well-known types.
+// Each wrapper type is included separately, as languages
+// map handle different wrappers in different ways.
 message TestWellKnownTypes {
   google.protobuf.Any any_field = 1;
   google.protobuf.Api api_field = 2;
@@ -27,5 +30,83 @@ message TestWellKnownTypes {
   google.protobuf.Struct struct_field = 7;
   google.protobuf.Timestamp timestamp_field = 8;
   google.protobuf.Type type_field = 9;
-  google.protobuf.Int32Value int32_field = 10;
+  google.protobuf.DoubleValue double_field = 10;
+  google.protobuf.FloatValue float_field = 11;
+  google.protobuf.Int64Value int64_field = 12;
+  google.protobuf.UInt64Value uint64_field = 13;
+  google.protobuf.Int32Value int32_field = 14;
+  google.protobuf.UInt32Value uint32_field = 15;
+  google.protobuf.BoolValue bool_field = 16;
+  google.protobuf.StringValue string_field = 17;
+  google.protobuf.BytesValue bytes_field = 18;
+}
+
+// A repeated field for each well-known type.
+message RepeatedWellKnownTypes {
+  repeated google.protobuf.Any any_field = 1;
+  repeated google.protobuf.Api api_field = 2;
+  repeated google.protobuf.Duration duration_field = 3;
+  repeated google.protobuf.Empty empty_field = 4;
+  repeated google.protobuf.FieldMask field_mask_field = 5;
+  repeated google.protobuf.SourceContext source_context_field = 6;
+  repeated google.protobuf.Struct struct_field = 7;
+  repeated google.protobuf.Timestamp timestamp_field = 8;
+  repeated google.protobuf.Type type_field = 9;
+  // These don't actually make a lot of sense, but they're not prohibited...
+  repeated google.protobuf.DoubleValue double_field = 10;
+  repeated google.protobuf.FloatValue float_field = 11;
+  repeated google.protobuf.Int64Value int64_field = 12;
+  repeated google.protobuf.UInt64Value uint64_field = 13;
+  repeated google.protobuf.Int32Value int32_field = 14;
+  repeated google.protobuf.UInt32Value uint32_field = 15;
+  repeated google.protobuf.BoolValue bool_field = 16;
+  repeated google.protobuf.StringValue string_field = 17;
+  repeated google.protobuf.BytesValue bytes_field = 18;
+}
+
+message OneofWellKnownTypes {
+  oneof oneof_field {
+    google.protobuf.Any any_field = 1;
+    google.protobuf.Api api_field = 2;
+    google.protobuf.Duration duration_field = 3;
+    google.protobuf.Empty empty_field = 4;
+    google.protobuf.FieldMask field_mask_field = 5;
+    google.protobuf.SourceContext source_context_field = 6;
+    google.protobuf.Struct struct_field = 7;
+    google.protobuf.Timestamp timestamp_field = 8;
+    google.protobuf.Type type_field = 9;
+    google.protobuf.DoubleValue double_field = 10;
+    google.protobuf.FloatValue float_field = 11;
+    google.protobuf.Int64Value int64_field = 12;
+    google.protobuf.UInt64Value uint64_field = 13;
+    google.protobuf.Int32Value int32_field = 14;
+    google.protobuf.UInt32Value uint32_field = 15;
+    google.protobuf.BoolValue bool_field = 16;
+    google.protobuf.StringValue string_field = 17;
+    google.protobuf.BytesValue bytes_field = 18;
+  }
+}
+
+// A map field for each well-known type. We only
+// need to worry about the value part of the map being the
+// well-known types, as messages can't be map keys.
+message MapWellKnownTypes {
+  map<int32,google.protobuf.Any> any_field = 1;
+  map<int32,google.protobuf.Api> api_field = 2;
+  map<int32,google.protobuf.Duration> duration_field = 3;
+  map<int32,google.protobuf.Empty> empty_field = 4;
+  map<int32,google.protobuf.FieldMask> field_mask_field = 5;
+  map<int32,google.protobuf.SourceContext> source_context_field = 6;
+  map<int32,google.protobuf.Struct> struct_field = 7;
+  map<int32,google.protobuf.Timestamp> timestamp_field = 8;
+  map<int32,google.protobuf.Type> type_field = 9;
+  map<int32,google.protobuf.DoubleValue> double_field = 10;
+  map<int32,google.protobuf.FloatValue> float_field = 11;
+  map<int32,google.protobuf.Int64Value> int64_field = 12;
+  map<int32,google.protobuf.UInt64Value> uint64_field = 13;
+  map<int32,google.protobuf.Int32Value> int32_field = 14;
+  map<int32,google.protobuf.UInt32Value> uint32_field = 15;
+  map<int32,google.protobuf.BoolValue> bool_field = 16;
+  map<int32,google.protobuf.StringValue> string_field = 17;
+  map<int32,google.protobuf.BytesValue> bytes_field = 18;
 }
diff --git a/src/google/protobuf/unknown_enum_test.proto b/src/google/protobuf/unknown_enum_test.proto
index 3c549cc7..0ea1ede3 100644
--- a/src/google/protobuf/unknown_enum_test.proto
+++ b/src/google/protobuf/unknown_enum_test.proto
@@ -36,8 +36,6 @@ syntax = "proto2";
 
 package google.protobuf.util;
 
-option csharp_namespace = "Google.ProtocolBuffers.TestProtos";
-
 message DownRevision {
   enum Enum {
     DEFAULT_VALUE = 2;
diff --git a/src/google/protobuf/wrappers.pb.cc b/src/google/protobuf/wrappers.pb.cc
index ffc77f1c..db75db15 100644
--- a/src/google/protobuf/wrappers.pb.cc
+++ b/src/google/protobuf/wrappers.pb.cc
@@ -262,9 +262,9 @@ void protobuf_AddDesc_google_2fprotobuf_2fwrappers_2eproto() {
     "e\030\001 \001(\004\"\033\n\nInt32Value\022\r\n\005value\030\001 \001(\005\"\034\n\013"
     "UInt32Value\022\r\n\005value\030\001 \001(\r\"\032\n\tBoolValue\022"
     "\r\n\005value\030\001 \001(\010\"\034\n\013StringValue\022\r\n\005value\030\001"
-    " \001(\t\"\033\n\nBytesValue\022\r\n\005value\030\001 \001(\014BE\n\023com"
+    " \001(\t\"\033\n\nBytesValue\022\r\n\005value\030\001 \001(\014BM\n\023com"
     ".google.protobufB\rWrappersProtoP\001\242\002\003GPB\252"
-    "\002\026Google.ProtocolBuffersb\006proto3", 392);
+    "\002\036Google.Protobuf.WellKnownTypesb\006proto3", 400);
   ::google::protobuf::MessageFactory::InternalRegisterGeneratedFile(
     "google/protobuf/wrappers.proto", &protobuf_RegisterTypes);
   DoubleValue::default_instance_ = new DoubleValue();
diff --git a/src/google/protobuf/wrappers.proto b/src/google/protobuf/wrappers.proto
index a13e6edb..6d3181bf 100644
--- a/src/google/protobuf/wrappers.proto
+++ b/src/google/protobuf/wrappers.proto
@@ -40,7 +40,7 @@ package google.protobuf;
 option java_multiple_files = true;
 option java_outer_classname = "WrappersProto";
 option java_package = "com.google.protobuf";
-option csharp_namespace = "Google.ProtocolBuffers";
+option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option objc_class_prefix = "GPB";