Add 'apple_watch1_extension' and 'apple_watch_extension_binary' to support building watch OS 1 apps.

RELNOTES: Support apple_watch1_extension and apple_watch_extension_binary rules for creating watch OS 1 extensions.

--
MOS_MIGRATED_REVID=119000703

26 files changed, 1932 insertions, 70 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1Extension.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1Extension.java
new file mode 100644
index 0000000000..7e0b328549
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1Extension.java
@@ -0,0 +1,224 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import static com.google.devtools.build.lib.rules.objc.AppleWatch1ExtensionRule.WATCH_APP_DEPS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.FLAG;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.Flag.HAS_WATCH1_EXTENSION;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MERGE_ZIP;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_NAME_ATTR;
+
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.ConfiguredTarget;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.config.BuildOptions;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
+import com.google.devtools.build.lib.rules.RuleConfiguredTargetFactory;
+import com.google.devtools.build.lib.rules.objc.IosExtension.ExtensionSplitArchTransition;
+import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition.ConfigurationDistinguisher;
+import com.google.devtools.build.lib.rules.objc.WatchUtils.WatchOSVersion;
+import com.google.devtools.build.lib.rules.test.InstrumentedFilesCollector;
+import com.google.devtools.build.lib.rules.test.InstrumentedFilesProvider;
+import com.google.devtools.build.lib.syntax.Type;
+
+/**
+ * Implementation for {@code apple_watch1_extension}.
+ */
+public class AppleWatch1Extension implements RuleConfiguredTargetFactory {
+
+  static final SplitTransition<BuildOptions> MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION =
+      new ExtensionSplitArchTransition(WatchUtils.MINIMUM_OS_VERSION,
+          ConfigurationDistinguisher.WATCH_OS1_EXTENSION);
+  private static final ImmutableSet<Attribute> extensionDependencyAttributes =
+      ImmutableSet.of(new Attribute("binary", Mode.SPLIT));
+  private static final ImmutableSet<Attribute> applicationDependencyAttributes =
+      ImmutableSet.of(new Attribute(WATCH_APP_DEPS_ATTR, Mode.SPLIT));
+
+  @Override
+  public ConfiguredTarget create(RuleContext ruleContext) throws InterruptedException {
+    ObjcProvider.Builder applicationObjcProviderBuilder = new ObjcProvider.Builder();
+    ObjcProvider.Builder extensionObjcProviderBuilder = new ObjcProvider.Builder();
+    XcodeProvider.Builder applicationXcodeProviderBuilder = new XcodeProvider.Builder();
+    XcodeProvider.Builder extensionXcodeProviderBuilder = new XcodeProvider.Builder();
+    NestedSetBuilder<Artifact> applicationFilesToBuild = NestedSetBuilder.stableOrder();
+    NestedSetBuilder<Artifact> extensionfilesToBuild = NestedSetBuilder.stableOrder();
+
+    // 1. Build watch application bundle.
+    createWatchApplicationBundle(ruleContext, applicationXcodeProviderBuilder,
+        applicationObjcProviderBuilder, applicationFilesToBuild);
+
+    // 2. Build watch extension bundle.
+    createWatchExtensionBundle(ruleContext, extensionXcodeProviderBuilder,
+        applicationXcodeProviderBuilder, extensionObjcProviderBuilder, extensionfilesToBuild);
+
+    // 3. Extract the watch application bundle into the extension bundle.
+    registerWatchApplicationUnBundlingAction(ruleContext);
+
+    RuleConfiguredTargetBuilder targetBuilder =
+        ObjcRuleClasses.ruleConfiguredTarget(ruleContext, extensionfilesToBuild.build())
+            .addProvider(XcodeProvider.class, extensionXcodeProviderBuilder.build())
+            .addProvider(
+                InstrumentedFilesProvider.class,
+                InstrumentedFilesCollector.forward(ruleContext, "binary"));
+
+    // 4. Exposed {@ObjcProvider} for bundling into final IPA.
+    exposeObjcProvider(ruleContext, targetBuilder);
+
+    return targetBuilder.build();
+  }
+
+  /**
+   * Exposes an {@link ObjcProvider} with the following to create the final IPA:
+   *    1. Watch extension bundle.
+   *    2. WatchKitSupport.
+   *    3. A flag to indicate that watch os 1 extension is included.
+   */
+  private void exposeObjcProvider(RuleContext ruleContext,
+      RuleConfiguredTargetBuilder targetBuilder) throws InterruptedException {
+    ObjcProvider.Builder exposedObjcProviderBuilder = new ObjcProvider.Builder();
+
+    exposedObjcProviderBuilder.add(MERGE_ZIP,
+        ruleContext.getImplicitOutputArtifact(ReleaseBundlingSupport.IPA));
+    WatchUtils.registerActionsToAddWatchSupport(ruleContext, exposedObjcProviderBuilder,
+        WatchOSVersion.OS1);
+    exposedObjcProviderBuilder.add(FLAG, HAS_WATCH1_EXTENSION);
+
+    targetBuilder.addProvider(ObjcProvider.class, exposedObjcProviderBuilder.build());
+  }
+
+  /**
+   * Creates a watch extension bundle.
+   *
+   * @param ruleContext rule context in which to create the bundle
+   * @param extensionXcodeProviderBuilder {@link XcodeProvider.Builder} for the extension
+   * @param applicationXcodeProviderBuilder {@link XcodeProvider.Builder} for the watch application
+   *    which is added as a dependency to the extension
+   * @param objcProviderBuilder {@link ObjcProvider.Builder} for the extension
+   * @param filesToBuild the list to contain the files to be built for this extension bundle
+   */
+  private void createWatchExtensionBundle(RuleContext ruleContext,
+      XcodeProvider.Builder extensionXcodeProviderBuilder,
+      XcodeProvider.Builder applicationXcodeProviderBuilder,
+      ObjcProvider.Builder objcProviderBuilder,
+      NestedSetBuilder<Artifact> filesToBuild) throws InterruptedException {
+    new WatchExtensionSupport(ruleContext,
+        WatchOSVersion.OS1,
+        extensionDependencyAttributes,
+        ObjcRuleClasses.intermediateArtifacts(ruleContext),
+        watchExtensionBundleName(ruleContext),
+        watchExtensionIpaArtifact(ruleContext),
+        watchApplicationBundle(ruleContext),
+        applicationXcodeProviderBuilder.build(),
+        ConfigurationDistinguisher.WATCH_OS1_EXTENSION)
+    .createBundle(filesToBuild, objcProviderBuilder, extensionXcodeProviderBuilder);
+  }
+
+  /**
+   * Creates a watch application bundle.
+   * 
+   * @param ruleContext rule context in which to create the bundle
+   * @param xcodeProviderBuilder {@link XcodeProvider.Builder} for the application
+   * @param objcProviderBuilder {@link ObjcProvider.Builder} for the application
+   * @param filesToBuild the list to contain the files to be built for this bundle
+   */
+  private void createWatchApplicationBundle(RuleContext ruleContext,
+      XcodeProvider.Builder xcodeProviderBuilder,
+      ObjcProvider.Builder objcProviderBuilder,
+      NestedSetBuilder<Artifact> filesToBuild) throws InterruptedException {
+    new WatchApplicationSupport(ruleContext,
+        WatchOSVersion.OS1,
+        applicationDependencyAttributes,
+        new IntermediateArtifacts(ruleContext, "",
+            watchApplicationBundleName(ruleContext)),
+        watchApplicationBundleName(ruleContext),
+        watchApplicationIpaArtifact(ruleContext),
+        watchApplicationBundleName(ruleContext),
+        ConfigurationDistinguisher.WATCH_OS1_EXTENSION)
+    .createBundle(xcodeProviderBuilder, objcProviderBuilder, filesToBuild);
+  }
+
+  /**
+   * Registers action to extract the watch application ipa (after signing if required) to the
+   * extension bundle.
+   *
+   * For example, TestWatchApp.ipa will be unbundled into,
+   *   PlugIns/TestWatchExtension.appex
+   *   PlugIns/TestWatchExtension.appex/TestWatchApp.app
+   */
+  private void registerWatchApplicationUnBundlingAction(RuleContext ruleContext) {
+    Artifact watchApplicationIpa = watchApplicationIpaArtifact(ruleContext);
+    Artifact watchApplicationBundle = watchApplicationBundle(ruleContext);
+
+    String workingDirectory = watchApplicationBundle.getExecPathString().substring(0,
+        watchApplicationBundle.getExecPathString().lastIndexOf('/'));
+
+    ImmutableList<String> command = ImmutableList.of(
+        "mkdir -p " + workingDirectory,
+        "&&",
+        String.format("/usr/bin/unzip -q %s -d %s",
+            watchApplicationIpa.getExecPathString(),
+            workingDirectory),
+        "&&",
+        String.format("cd %s/Payload", workingDirectory),
+        "&&",
+        String.format("/usr/bin/zip -q -r -0 ../%s *", watchApplicationBundle.getFilename()));
+    ruleContext.registerAction(
+        ObjcRuleClasses.spawnOnDarwinActionBuilder()
+            .setProgressMessage("Extracting watch app: " + ruleContext.getLabel())
+            .setShellCommand(ImmutableList.of("/bin/bash", "-c", Joiner.on(" ").join(command)))
+            .addInput(watchApplicationIpa)
+            .addOutput(watchApplicationBundle)
+            .build(ruleContext));
+  }
+
+  /**
+   * Returns a zip {@Artifact} containing extracted watch application - "TestWatchApp.app"
+   * which is to be merged into the extension bundle.
+   */
+  private Artifact watchApplicationBundle(RuleContext ruleContext) {
+    return ruleContext.getRelatedArtifact(ruleContext.getUniqueDirectory(
+        "_watch"), String.format("/%s", watchApplicationIpaArtifact(ruleContext)
+            .getFilename().replace(".ipa", ".zip")));
+  }
+
+  /**
+   * Returns the {@Artifact} containing final watch application bundle.
+   */
+  private Artifact watchApplicationIpaArtifact(RuleContext ruleContext) {
+    return ruleContext.getRelatedArtifact(ruleContext.getUniqueDirectory("_watch"),
+          String.format("/%s.ipa", watchApplicationBundleName(ruleContext)));
+  }
+
+  /**
+   * Returns the {@Artifact} containing final watch extension bundle.
+   */
+  private Artifact watchExtensionIpaArtifact(RuleContext ruleContext) throws InterruptedException {
+    return ruleContext.getImplicitOutputArtifact(ReleaseBundlingSupport.IPA);
+  }
+
+  private String watchApplicationBundleName(RuleContext ruleContext) {
+    return ruleContext.attributes().get(WATCH_APP_NAME_ATTR, Type.STRING);
+  }
+
+  private String watchExtensionBundleName(RuleContext ruleContext) {
+    return ruleContext.getLabel().getName();
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1ExtensionRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1ExtensionRule.java
new file mode 100644
index 0000000000..04bf382eec
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatch1ExtensionRule.java
@@ -0,0 +1,98 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import static com.google.devtools.build.lib.packages.Attribute.attr;
+import static com.google.devtools.build.lib.packages.BuildType.LABEL;
+import static com.google.devtools.build.lib.packages.BuildType.LABEL_LIST;
+
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.analysis.BaseRuleClasses;
+import com.google.devtools.build.lib.analysis.RuleDefinition;
+import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.packages.ImplicitOutputsFunction;
+import com.google.devtools.build.lib.packages.RuleClass;
+import com.google.devtools.build.lib.packages.RuleClass.Builder;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+
+/**
+ * Rule definition for apple_watch1_extension.
+ */
+public class AppleWatch1ExtensionRule implements RuleDefinition {
+
+  private static final Iterable<String> ALLOWED_DEPS_RULE_CLASSES =
+      ImmutableSet.of("objc_library", "objc_import");
+  static final String WATCH_APP_DEPS_ATTR  = "app_deps";
+
+  @Override
+  public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+    return builder
+        .requiresConfigurationFragments(ObjcConfiguration.class, AppleConfiguration.class)
+        /*<!-- #BLAZE_RULE(apple_watch1_extension).IMPLICIT_OUTPUTS -->
+        <ul>
+         <li><code><var>name</var>.ipa</code>: the extension bundle as an <code>.ipa</code>
+             file</li>
+         <li><code><var>name</var>.xcodeproj/project.pbxproj</code>: An Xcode project file which
+             can be used to develop or build on a Mac.</li>
+        </ul>
+        <!-- #END_BLAZE_RULE.IMPLICIT_OUTPUTS -->*/
+        .setImplicitOutputsFunction(
+            ImplicitOutputsFunction.fromFunctions(ReleaseBundlingSupport.IPA, XcodeSupport.PBXPROJ))
+        /* <!-- #BLAZE_RULE(apple_watch1_extension).ATTRIBUTE(binary) -->
+        The binary target containing the logic for the watch extension.
+        ${SYNOPSIS}
+        <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+        .add(attr("binary", LABEL)
+            .allowedRuleClasses("apple_watch_extension_binary")
+            .allowedFileTypes()
+            .mandatory()
+            .direct_compile_time_input()
+            .cfg(AppleWatch1Extension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION))
+        /* <!-- #BLAZE_RULE($apple_watch1_extension).ATTRIBUTE(deps) -->
+        The list of targets whose resources files are bundled together to form final watch
+        application bundle.
+        <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+       .add(attr(WATCH_APP_DEPS_ATTR, LABEL_LIST)
+           .direct_compile_time_input()
+           .allowedRuleClasses(ALLOWED_DEPS_RULE_CLASSES)
+           .allowedFileTypes()
+           .cfg(AppleWatch1Extension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION))
+        .build();
+  }
+
+  @Override
+
+  public Metadata getMetadata() {
+    return RuleDefinition.Metadata.builder()
+        .name("apple_watch1_extension")
+        .factoryClass(AppleWatch1Extension.class)
+        .ancestors(BaseRuleClasses.BaseRule.class,
+            ObjcRuleClasses.XcodegenRule.class,
+            ObjcRuleClasses.WatchApplicationBundleRule.class,
+            ObjcRuleClasses.WatchExtensionBundleRule.class)
+        .build();
+  }
+}
+
+/*<!-- #BLAZE_RULE (NAME = apple_watch1_extension, TYPE = BINARY, FAMILY = Objective-C) -->
+
+<p>This rule produces an extension bundle for apple watch OS 1 which also contains the watch
+application bundle</p>
+
+${IMPLICIT_OUTPUTS}
+
+${ATTRIBUTE_DEFINITION}
+
+<!-- #END_BLAZE_RULE -->*/
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinary.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinary.java
new file mode 100644
index 0000000000..675c82a0d7
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinary.java
@@ -0,0 +1,33 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.rules.objc.CompilationSupport.ExtraLinkArgs;
+
+/**
+ * Implementation for the "apple_watch_extension_binary" rule.
+ */
+public class AppleWatchExtensionBinary extends BinaryLinkingTargetFactory {
+
+  public AppleWatchExtensionBinary() {
+    super(HasReleaseBundlingSupport.NO, XcodeProductType.LIBRARY_STATIC);
+  }
+
+  @Override
+  protected ExtraLinkArgs getExtraLinkArgs(RuleContext ruleContext) {
+    return new ExtraLinkArgs("-fapplication-extension", "-framework", "WatchKit");
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinaryRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinaryRule.java
new file mode 100644
index 0000000000..a65502e7a1
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/AppleWatchExtensionBinaryRule.java
@@ -0,0 +1,61 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import com.google.devtools.build.lib.analysis.BaseRuleClasses;
+import com.google.devtools.build.lib.analysis.RuleDefinition;
+import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
+import com.google.devtools.build.lib.packages.RuleClass;
+import com.google.devtools.build.lib.packages.RuleClass.Builder;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+
+/**
+ * Rule definition for apple_watch_extension_binary.
+ */
+public class AppleWatchExtensionBinaryRule implements RuleDefinition {
+  @Override
+  public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+    return builder
+        .requiresConfigurationFragments(ObjcConfiguration.class, J2ObjcConfiguration.class,
+            AppleConfiguration.class)
+        /*<!-- #BLAZE_RULE(apple_watch_extension_binary).IMPLICIT_OUTPUTS -->
+        <ul>
+         <li><code><var>name</var>.xcodeproj/project.pbxproj</code>: An Xcode project file which
+             can be used to develop or build on a Mac.</li>
+        </ul>
+        <!-- #END_BLAZE_RULE.IMPLICIT_OUTPUTS -->*/
+        .setImplicitOutputsFunction(XcodeSupport.PBXPROJ)
+        .build();
+  }
+
+  @Override
+  public Metadata getMetadata() {
+    return RuleDefinition.Metadata.builder()
+        .name("apple_watch_extension_binary")
+        .factoryClass(AppleWatchExtensionBinary.class)
+        .ancestors(BaseRuleClasses.BaseRule.class, ObjcRuleClasses.LinkingRule.class,
+            ObjcRuleClasses.XcodegenRule.class)
+        .build();
+  }
+}
+
+/*<!-- #BLAZE_RULE (NAME = apple_watch_extension_binary, TYPE = BINARY, FAMILY = Objective-C) -->
+
+<p>This rule produces a binary for watch extension by linking one or more
+Objective-C libraries.</p>
+
+${IMPLICIT_OUTPUTS}
+
+<!-- #END_BLAZE_RULE -->*/
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
index 70925770e5..f7a83beeb0 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleMergeControlBytes.java
@@ -63,7 +63,7 @@ final class BundleMergeControlBytes extends ByteSource {
     if (bundling.getBundleInfoplist().isPresent()) {
       control.setBundleInfoPlistFile((bundling.getBundleInfoplist().get().getExecPathString()));
     }
-    
+
     for (Artifact mergeZip : bundling.getMergeZips()) {
       control.addMergeZip(MergeZip.newBuilder()
           .setEntryNamePrefix(mergeZipPrefix)
@@ -71,6 +71,13 @@ final class BundleMergeControlBytes extends ByteSource {
           .build());
     }
 
+    for (Artifact rootMergeZip : bundling.getRootMergeZips()) {
+      control.addMergeZip(MergeZip.newBuilder()
+          .setEntryNamePrefix("")
+          .setSourcePath(rootMergeZip.getExecPathString())
+          .build());
+    }
+
     control.setOutFile(mergedIpa.getExecPathString());
 
     for (Artifact linkedBinary : bundling.getCombinedArchitectureBinary().asSet()) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleSupport.java
index d1b7ab4c32..abbeba537c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/BundleSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/BundleSupport.java
@@ -20,6 +20,7 @@ import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STRINGS;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.XCASSETS_DIR;
 
 import com.google.common.base.Optional;
+import com.google.common.base.Predicate;
 import com.google.common.base.Verify;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
@@ -218,10 +219,36 @@ final class BundleSupport {
   ImmutableSet<TargetDeviceFamily> targetDeviceFamilies() {
     return bundling.getTargetDeviceFamilies();
   }
+ 
+  /**
+   * Returns true if this bundle is targeted to {@link TargetDeviceFamily#WATCH}, false otherwise.
+   */
+  boolean isBuildingForWatch() {
+    return Iterables.any(targetDeviceFamilies(),
+        new Predicate<TargetDeviceFamily>() {
+      @Override
+      public boolean apply(TargetDeviceFamily targetDeviceFamily) {
+        return targetDeviceFamily.name().equalsIgnoreCase(TargetDeviceFamily.WATCH.getNameInRule());
+      }
+    });
+  }
+
+  /**
+   * Returns a set containing the {@link TargetDeviceFamily} values the resources in this bundle
+   * are targeting. When watch is included as one of the families, (for example [iphone, watch] for
+   * simulator builds, assets should always be compiled for {@link TargetDeviceFamily#WATCH}.
+   */
+  private ImmutableSet<TargetDeviceFamily> targetDeviceFamiliesForResources() {
+    if (isBuildingForWatch()) {
+      return ImmutableSet.of(TargetDeviceFamily.WATCH);
+    } else {
+      return targetDeviceFamilies();
+    }
+  }
 
   private void registerInterfaceBuilderActions(ObjcProvider objcProvider) {
     for (Artifact storyboardInput : objcProvider.get(ObjcProvider.STORYBOARD)) {
-      String archiveRoot = BundleableFile.flatBundlePath(storyboardInput.getExecPath()) + "c";
+      String archiveRoot = storyboardArchiveRoot(storyboardInput);
       Artifact zipOutput = bundling.getIntermediateArtifacts()
           .compiledStoryboardZip(storyboardInput);
 
@@ -236,6 +263,22 @@ final class BundleSupport {
     }
   }
 
+  /**
+   * Returns the root file path to which storyboard interfaces are compiled.
+   */
+  protected String storyboardArchiveRoot(Artifact storyboardInput) {
+    // When storyboards are compiled for {@link TargetDeviceFamily#WATCH}, return the containing
+    // directory if it ends with .lproj to account for localization or "." representing the bundle
+    // root otherwise. Examples: Payload/Foo.app/Base.lproj/<compiled_file>,
+    // Payload/Foo.app/<compile_file_1>
+    if (isBuildingForWatch()) {
+      String containingDir = storyboardInput.getExecPath().getParentDirectory().getBaseName();
+      return containingDir.endsWith(".lproj") ? (containingDir + "/") : ".";
+    } else {
+      return BundleableFile.flatBundlePath(storyboardInput.getExecPath()) + "c";
+    }
+  }
+
   private CommandLine ibActionsCommandLine(String archiveRoot, Artifact zipOutput,
       Artifact storyboardInput) {
     CustomCommandLine.Builder commandLine =
@@ -248,7 +291,7 @@ final class BundleSupport {
             .add("--module")
             .add(ruleContext.getLabel().getName());
 
-    for (TargetDeviceFamily targetDeviceFamily : targetDeviceFamilies()) {
+    for (TargetDeviceFamily targetDeviceFamily : targetDeviceFamiliesForResources()) {
       commandLine.add("--target-device").add(targetDeviceFamily.name().toLowerCase(Locale.US));
     }
 
@@ -406,7 +449,7 @@ final class BundleSupport {
             .add("--minimum-deployment-target")
             .add(bundling.getMinimumOsVersion().toString());
 
-    for (TargetDeviceFamily targetDeviceFamily : targetDeviceFamilies()) {
+    for (TargetDeviceFamily targetDeviceFamily : targetDeviceFamiliesForResources()) {
       commandLine.add("--target-device").add(targetDeviceFamily.name().toLowerCase(Locale.US));
     }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/Bundling.java b/src/main/java/com/google/devtools/build/lib/rules/objc/Bundling.java
index 90864205a0..35c228bb0b 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/Bundling.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/Bundling.java
@@ -21,6 +21,7 @@ import static com.google.devtools.build.lib.rules.objc.ObjcProvider.IMPORTED_LIB
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.LIBRARY;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MERGE_ZIP;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.NESTED_BUNDLE;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.ROOT_MERGE_ZIP;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STORYBOARD;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STRINGS;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.XCDATAMODEL;
@@ -289,6 +290,9 @@ final class Bundling {
       Optional<Artifact> combinedArchitectureBinary = combinedArchitectureBinary();
       NestedSet<BundleableFile> binaryStringsFiles = binaryStringsFiles();
       NestedSet<Artifact> mergeZips = mergeZips(actoolzipOutput);
+      NestedSet<Artifact> rootMergeZips =
+          NestedSetBuilder.<Artifact>stableOrder()
+              .addTransitive(objcProvider.get(ROOT_MERGE_ZIP)).build();
 
       bundleFilesBuilder.addAll(binaryStringsFiles).addAll(objcProvider.get(BUNDLE_FILE));
       ImmutableList<BundleableFile> bundleFiles =
@@ -300,6 +304,7 @@ final class Bundling {
               .addAll(combinedArchitectureBinary.asSet())
               .addAll(bundleInfoplist.asSet())
               .addTransitive(mergeZips)
+              .addTransitive(rootMergeZips)
               .addAll(BundleableFile.toArtifacts(binaryStringsFiles))
               .addAll(BundleableFile.toArtifacts(bundleFiles));
 
@@ -312,6 +317,7 @@ final class Bundling {
           actoolzipOutput,
           bundleContentArtifactsBuilder.build(),
           mergeZips,
+          rootMergeZips,
           primaryBundleId,
           fallbackBundleId,
           architecture,
@@ -340,6 +346,7 @@ final class Bundling {
   private final Optional<Artifact> actoolzipOutput;
   private final NestedSet<Artifact> bundleContentArtifacts;
   private final NestedSet<Artifact> mergeZips;
+  private final NestedSet<Artifact> rootMergeZips;
   private final String primaryBundleId;
   private final String fallbackBundleId;
   private final DottedVersion minimumOsVersion;
@@ -359,6 +366,7 @@ final class Bundling {
       Optional<Artifact> actoolzipOutput,
       NestedSet<Artifact> bundleContentArtifacts,
       NestedSet<Artifact> mergeZips,
+      NestedSet<Artifact> rootMergeZips,
       String primaryBundleId,
       String fallbackBundleId,
       String architecture,
@@ -378,6 +386,7 @@ final class Bundling {
     this.actoolzipOutput = Preconditions.checkNotNull(actoolzipOutput);
     this.bundleContentArtifacts = Preconditions.checkNotNull(bundleContentArtifacts);
     this.mergeZips = Preconditions.checkNotNull(mergeZips);
+    this.rootMergeZips = Preconditions.checkNotNull(rootMergeZips);
     this.fallbackBundleId = fallbackBundleId;
     this.primaryBundleId = primaryBundleId;
     this.architecture = Preconditions.checkNotNull(architecture);
@@ -495,6 +504,19 @@ final class Bundling {
   }
 
   /**
+   * Returns all zip files whose contents should be merged into final ipa and outside the
+   * main bundle. For instance, if a merge zip contains files dir1/file1, then the resulting
+   * bundling would have additional files at:
+   * <ul>
+   *   <li>dir1/file1
+   *   <li>{bundleDir}/other_files
+   * </ul>
+   */
+  public NestedSet<Artifact> getRootMergeZips() {
+    return rootMergeZips;
+  }
+
+  /**
    * Returns the variable substitutions that should be used when merging the plist info file of
    * this bundle.
    */
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
index e57187fbc6..62cec0444c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IntermediateArtifacts.java
@@ -35,10 +35,17 @@ public final class IntermediateArtifacts {
 
   private final RuleContext ruleContext;
   private final String archiveFileNameSuffix;
+  private final String outputPrefix;
 
   IntermediateArtifacts(RuleContext ruleContext, String archiveFileNameSuffix) {
+    this(ruleContext, archiveFileNameSuffix, "");
+  }
+ 
+  IntermediateArtifacts(RuleContext ruleContext, String archiveFileNameSuffix,
+      String outputPrefix) {
     this.ruleContext = ruleContext;
     this.archiveFileNameSuffix = Preconditions.checkNotNull(archiveFileNameSuffix);
+    this.outputPrefix = Preconditions.checkNotNull(outputPrefix);
   }
 
   /**
@@ -52,7 +59,7 @@ public final class IntermediateArtifacts {
     Artifact artifact =
         ruleContext.getDerivedArtifact(
             entitlementsDirectory.replaceName(
-                entitlementsDirectory.getBaseName() + extension),
+                addOutputPrefix(entitlementsDirectory.getBaseName(), extension)),
             ruleContext.getConfiguration().getBinDirectory());
     return artifact;
   }
@@ -69,7 +76,8 @@ public final class IntermediateArtifacts {
    * of the given {@link PathFragment}.
    */
   private Artifact appendExtension(PathFragment original, String extension) {
-    return scopedArtifact(FileSystemUtils.appendExtension(original, extension));
+    return scopedArtifact(FileSystemUtils.appendExtension(original,
+        addOutputPrefix("", extension)));
   }
 
   /**
@@ -78,7 +86,7 @@ public final class IntermediateArtifacts {
    */
   private Artifact appendExtension(String extension) {
     PathFragment name = new PathFragment(ruleContext.getLabel().getName());
-    return scopedArtifact(name.replaceName(name.getBaseName() + extension));
+    return scopedArtifact(name.replaceName(addOutputPrefix(name.getBaseName(), extension)));
   }
 
   /**
@@ -97,7 +105,7 @@ public final class IntermediateArtifacts {
   private Artifact appendExtensionInGenfiles(String extension) {
     PathFragment name = new PathFragment(ruleContext.getLabel().getName());
     return scopedArtifact(
-        name.replaceName(name.getBaseName() + extension), /* inGenfiles = */ true);
+        name.replaceName(addOutputPrefix(name.getBaseName(), extension)), /* inGenfiles = */ true);
   }
 
   /**
@@ -404,4 +412,15 @@ public final class IntermediateArtifacts {
   public Artifact unprocessedIpa() {
     return appendExtension(".unprocessed.ipa");
   }
+
+  /**
+   * Returns artifact name prefixed with an output prefix if specified.
+   */
+  private String addOutputPrefix(String baseName, String artifactName) {
+    if (!outputPrefix.isEmpty()) {
+      return String.format("%s-%s%s", baseName, outputPrefix, artifactName);
+    }
+    return String.format("%s%s", baseName, artifactName);
+  }
+
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplication.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplication.java
index e23af613bd..f57e53a4b6 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplication.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplication.java
@@ -14,7 +14,10 @@
 
 package com.google.devtools.build.lib.rules.objc;
 
+import com.google.common.base.Predicate;
 import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.Iterables;
+import com.google.common.collect.Lists;
 import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
 import com.google.devtools.build.lib.analysis.RuleConfiguredTargetBuilder;
@@ -23,6 +26,7 @@ import com.google.devtools.build.lib.analysis.config.BuildOptions;
 import com.google.devtools.build.lib.packages.Attribute.SplitTransition;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
 import com.google.devtools.build.lib.rules.apple.Platform;
+import com.google.devtools.build.lib.rules.objc.ObjcProvider.Flag;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition;
 import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition.ConfigurationDistinguisher;
 
@@ -48,6 +52,29 @@ public class IosApplication extends ReleaseBundlingTargetFactory {
     super(ReleaseBundlingSupport.APP_BUNDLE_DIR_FORMAT, XcodeProductType.APPLICATION,
         DEPENDENCY_ATTRIBUTES, ConfigurationDistinguisher.IOS_APPLICATION);
   }
+  
+  /**
+   * Validates that there is exactly one watch extension for each OS version.
+   */
+  @Override
+  protected void validateAttributes(RuleContext ruleContext) {
+    Iterable<ObjcProvider> extensionProviders = ruleContext.getPrerequisites(
+        "extensions", Mode.TARGET, ObjcProvider.class);
+    if (hasMoreThanOneWatchExtension(extensionProviders, Flag.HAS_WATCH1_EXTENSION)) {
+      ruleContext.attributeError("extensions", "An iOS application can contain exactly one "
+          + "watch extension for each watch OS version");
+    }
+  }
+  
+  private boolean hasMoreThanOneWatchExtension(Iterable<ObjcProvider> objcProviders,
+      final Flag watchExtensionVersionFlag) {
+    return Lists.newArrayList(Iterables.filter(objcProviders, new Predicate<ObjcProvider>() {
+      @Override
+      public boolean apply(ObjcProvider objcProvider) {
+        return objcProvider.is(watchExtensionVersionFlag);
+      }
+    })).size() > 1;
+  }
 
   @Override
   protected void configureTarget(RuleConfiguredTargetBuilder target, RuleContext ruleContext,
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
index b7c369c7a8..c7a0a2bb26 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosApplicationRule.java
@@ -61,7 +61,7 @@ public class IosApplicationRule implements RuleDefinition {
         Any extensions to include in the final application.
         <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
         .add(attr("extensions", LABEL_LIST)
-            .allowedRuleClasses("ios_extension")
+            .allowedRuleClasses("ios_extension", "apple_watch1_extension")
             .allowedFileTypes()
             .direct_compile_time_input())
         .add(attr("$runner_script_template", LABEL).cfg(HOST)
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java b/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
index 8602a83bbf..b07a36ebb8 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/IosExtension.java
@@ -35,6 +35,10 @@ import java.io.Serializable;
  */
 public class IosExtension extends ReleaseBundlingTargetFactory {
 
+  // Apple only accepts extensions starting at 8.0.
+  @VisibleForTesting
+  static final DottedVersion EXTENSION_MINIMUM_OS_VERSION = DottedVersion.fromString("8.0");
+
   /**
    * Transition that when applied to a target generates a configured target for each value in
    * {@code --ios_multi_cpus}, such that {@code --ios_cpu} is set to a different one of those values
@@ -44,11 +48,8 @@ public class IosExtension extends ReleaseBundlingTargetFactory {
    * --ios_minimum_os} is at least {@code 8.0} as Apple requires this for extensions.
    */
   static final SplitTransition<BuildOptions> MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION =
-      new ExtensionSplitArchTransition();
-
-  // Apple only accepts extensions starting at 8.0.
-  @VisibleForTesting
-  static final DottedVersion EXTENSION_MINIMUM_OS_VERSION = DottedVersion.fromString("8.0");
+      new ExtensionSplitArchTransition(EXTENSION_MINIMUM_OS_VERSION,
+          ConfigurationDistinguisher.IOS_EXTENSION);
 
   public IosExtension() {
     super(ReleaseBundlingSupport.EXTENSION_BUNDLE_DIR_FORMAT, XcodeProductType.EXTENSION,
@@ -58,7 +59,8 @@ public class IosExtension extends ReleaseBundlingTargetFactory {
 
   @Override
   protected DottedVersion bundleMinimumOsVersion(RuleContext ruleContext) {
-    return determineMinimumOsVersion(ObjcRuleClasses.objcConfiguration(ruleContext).getMinimumOs());
+    return determineMinimumOsVersion(ObjcRuleClasses.objcConfiguration(ruleContext).getMinimumOs(),
+        EXTENSION_MINIMUM_OS_VERSION);
   }
 
   @Override
@@ -69,24 +71,43 @@ public class IosExtension extends ReleaseBundlingTargetFactory {
         .build();
   }
 
-  private static DottedVersion determineMinimumOsVersion(DottedVersion fromFlag) {
-    // Extensions are not accepted by Apple below version 8.0. While applications built with a
-    // minimum iOS version of less than 8.0 may contain extensions in their bundle, the extension
-    // itself needs to be built with 8.0 or higher. This logic overrides (if necessary) any
-    // flag-set minimum iOS version for extensions only so that this requirement is not violated.
-    return Ordering.natural().max(fromFlag, EXTENSION_MINIMUM_OS_VERSION);
+
+  /**
+   * Overrides (if necessary) any flag-set minimum iOS version for extensions only with given
+   * minimum OS version.
+   *
+   * Extensions are not accepted by Apple below given mininumOSVersion. While applications built
+   * with a minimum iOS version of less than give version may contain extensions in their bundle,
+   * the extension itself needs to be built with given version or higher.
+   *
+   * @param fromFlag the minimum OS version from command line flag
+   * @param minimumOSVersion the minumum OS version the extension should be built with
+   */
+  private static DottedVersion determineMinimumOsVersion(DottedVersion fromFlag,
+      DottedVersion minimumOSVersion) {
+    return Ordering.natural().max(fromFlag, minimumOSVersion);
   }
 
   /**
    * Split transition that configures the minimum iOS version in addition to architecture splitting.
    */
-  private static class ExtensionSplitArchTransition extends SplitArchTransition
+  static class ExtensionSplitArchTransition extends SplitArchTransition
       implements Serializable {
 
+    private final DottedVersion minimumOSVersion;
+    private final ConfigurationDistinguisher configurationDistinguisher;
+
+    ExtensionSplitArchTransition(DottedVersion minimumOSVersion,
+        ConfigurationDistinguisher configurationDistinguisher) {
+      this.minimumOSVersion = minimumOSVersion;
+      this.configurationDistinguisher = configurationDistinguisher;
+    }
+
     @Override
     protected ImmutableList<BuildOptions> defaultOptions(BuildOptions originalOptions) {
       ObjcCommandLineOptions objcOptions = originalOptions.get(ObjcCommandLineOptions.class);
-      DottedVersion newMinimumVersion = determineMinimumOsVersion(objcOptions.iosMinimumOs);
+      DottedVersion newMinimumVersion = determineMinimumOsVersion(objcOptions.iosMinimumOs,
+          minimumOSVersion);
 
       if (newMinimumVersion.equals(objcOptions.iosMinimumOs)) {
         return ImmutableList.of();
@@ -102,12 +123,12 @@ public class IosExtension extends ReleaseBundlingTargetFactory {
     @Override
     protected void setAdditionalOptions(BuildOptions splitOptions, BuildOptions originalOptions) {
       DottedVersion fromFlag = originalOptions.get(ObjcCommandLineOptions.class).iosMinimumOs;
-      setMinimumOsVersion(splitOptions, determineMinimumOsVersion(fromFlag));
+      setMinimumOsVersion(splitOptions, determineMinimumOsVersion(fromFlag, minimumOSVersion));
     }
 
     @Override
     protected ConfigurationDistinguisher getConfigurationDistinguisher() {
-      return ConfigurationDistinguisher.IOS_EXTENSION;
+      return configurationDistinguisher;
     }
 
     private void setMinimumOsVersion(BuildOptions splitOptions, DottedVersion newMinimumVersion) {
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
index 86e5b3df81..36bb1ea586 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommandLineOptions.java
@@ -206,7 +206,8 @@ public class ObjcCommandLineOptions extends FragmentOptions {
   @Override
   public List<SplitTransition<BuildOptions>> getPotentialSplitTransitions() {
     return ImmutableList.of(
-        IosApplication.SPLIT_ARCH_TRANSITION, IosExtension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION);
+        IosApplication.SPLIT_ARCH_TRANSITION, IosExtension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION,
+        AppleWatch1Extension.MINIMUM_OS_AND_SPLIT_ARCH_TRANSITION);
   }
 
   /** Converter for the iOS configuration distinguisher. */
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
index f2dd17810a..7f80a960b6 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcCommon.java
@@ -745,7 +745,7 @@ public final class ObjcCommon {
    * <p>When XCode sees a included resource directory of "a/b/res", the entire directory structure
    * up to "res" will be copied into the app bundle.
    */
-  private static Iterable<PathFragment> xcodeStructuredResourceDirs(Iterable<Artifact> artifacts) {
+  static Iterable<PathFragment> xcodeStructuredResourceDirs(Iterable<Artifact> artifacts) {
     ImmutableSet.Builder<PathFragment> containers = new ImmutableSet.Builder<>();
     for (Artifact artifact : artifacts) {
       PathFragment ownerRuleDirectory = artifact.getArtifactOwner().getLabel().getPackageFragment();
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
index aaaa7004f0..99968e924c 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcProvider.java
@@ -214,6 +214,17 @@ public final class ObjcProvider implements TransitiveInfoProvider {
       new Key<>(STABLE_ORDER, "merge_zip", Artifact.class);
 
   /**
+   * Merge zips to include in the ipa and outside the bundle root.
+   *
+   * e.g. For a bundle Test.ipa, unzipped content will be in:
+   *    Test.ipa/<unzipped>
+   *    Test.ipa/Payload
+   *    Test.ipa/Payload/Test.app
+   */
+  public static final Key<Artifact> ROOT_MERGE_ZIP =
+      new Key<>(STABLE_ORDER, "root_merge_zip", Artifact.class);
+
+  /**
    * Exec paths of {@code .framework} directories corresponding to frameworks to link. These cause
    * -F arguments (framework search paths) to be added to each compile action, and -framework (link
    * framework) arguments to be added to each link action.
@@ -312,8 +323,12 @@ public final class ObjcProvider implements TransitiveInfoProvider {
     /**
      * Indicates that the resulting bundle will have embedded frameworks. This affects linking step.
      */
-    USES_FRAMEWORKS
-
+    USES_FRAMEWORKS,
+    
+    /**
+     * Indicates that watch os 1 extension is present in the bundle.
+     */
+    HAS_WATCH1_EXTENSION
   }
 
   /**
@@ -325,7 +340,8 @@ public final class ObjcProvider implements TransitiveInfoProvider {
     ImmutableList.<Key<?>>of(LIBRARY, IMPORTED_LIBRARY, LINKED_BINARY, FORCE_LOAD_LIBRARY,
         FORCE_LOAD_FOR_XCODEGEN, HEADER, SOURCE, DEFINE, ASSET_CATALOG, GENERAL_RESOURCE_FILE,
         SDK_DYLIB, XCDATAMODEL, MODULE_MAP, MERGE_ZIP, FRAMEWORK_FILE, DEBUG_SYMBOLS,
-        DEBUG_SYMBOLS_PLIST, BREAKPAD_FILE, STORYBOARD, XIB, STRINGS, LINKOPT, J2OBJC_LIBRARY);
+        DEBUG_SYMBOLS_PLIST, BREAKPAD_FILE, STORYBOARD, XIB, STRINGS, LINKOPT, J2OBJC_LIBRARY,
+        ROOT_MERGE_ZIP);
 
   private final ImmutableMap<Key<?>, NestedSet<?>> items;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
index ee98c7d0d9..ef9e07911a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcRuleClasses.java
@@ -369,7 +369,7 @@ public class ObjcRuleClasses {
           Base.lproj), it will be placed under a directory of that name in the
           final bundle. This allows for localizable strings.
           <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
-          .add(attr("strings", LABEL_LIST).legacyAllowAnyFileType()
+          .add(attr("strings", LABEL_LIST)
               .allowedFileTypes(STRINGS_TYPE)
               .direct_compile_time_input())
           /* <!-- #BLAZE_RULE($objc_resources_rule).ATTRIBUTE(xibs) -->
@@ -962,6 +962,26 @@ public class ObjcRuleClasses {
                           return "example." + rule.getName();
                         }
                       }))
+          .build();
+    }
+    @Override
+    public Metadata getMetadata() {
+      return RuleDefinition.Metadata.builder()
+          .name("$objc_release_bundling_rule")
+          .type(RuleClassType.ABSTRACT)
+          .ancestors(BundlingRule.class, ReleaseBundlingToolsRule.class)
+          .build();
+    }
+  }
+
+  /**
+   * Common attributes for rules that require tools to create a bundle meant for
+   * release (e.g. application or extension).
+   */
+  public static class ReleaseBundlingToolsRule implements RuleDefinition {
+    @Override
+    public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+      return builder
           .add(
               attr("$bundlemerge", LABEL)
                   .cfg(HOST)
@@ -977,9 +997,8 @@ public class ObjcRuleClasses {
     @Override
     public Metadata getMetadata() {
       return RuleDefinition.Metadata.builder()
-          .name("$objc_release_bundling_rule")
+          .name("$release_bundling_tools_rule")
           .type(RuleClassType.ABSTRACT)
-          .ancestors(BundlingRule.class)
           .build();
     }
   }
@@ -1067,5 +1086,365 @@ public class ObjcRuleClasses {
           .build();
     }
   }
+
+  /**
+   * Attributes for {@code apple_watch*} rules that creates a watch extension bundle.
+   */
+  public static class WatchExtensionBundleRule implements RuleDefinition {
+    static final String WATCH_EXT_BUNDLE_ID_ATTR = "ext_bundle_id";
+    static final String WATCH_EXT_DEFAULT_PROVISIONING_PROFILE_ATTR =
+        ":default_ext_provisioning_profile";
+    static final String WATCH_EXT_ENTITLEMENTS_ATTR = "ext_entitlements";
+    static final String WATCH_EXT_PROVISIONING_PROFILE_ATTR = "ext_provisioning_profile";
+    static final String WATCH_EXT_INFOPLISTS_ATTR = "ext_infoplists";
+    static final String WATCH_EXT_RESOURCES_ATTR = "ext_resources";
+    static final String WATCH_EXT_STRUCTURED_RESOURCES_ATTR = "ext_structured_resources";
+    static final String WATCH_EXT_STRINGS_ATTR = "ext_strings";
+    static final String WATCH_EXT_FAMILIES_ATTR = "ext_families";
+
+    @Override
+    public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+      return builder
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_bundle_id) -->
+          The bundle ID (reverse-DNS path followed by app name) of the watch extension binary.
+
+          If specified, it will override the bundle ID specified in the associated plist file. If
+          no bundle ID is specified on either this attribute or in the plist file, a junk value
+          will be used.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr(WATCH_EXT_BUNDLE_ID_ATTR, STRING)
+                  .value(
+                      new Attribute.ComputedDefault() {
+                        @Override
+                        public Object getDefault(AttributeMap rule) {
+                          // For tests and similar, we don't want to force people to explicitly
+                          // specify throw-away data.
+                          return "example.ext." + rule.getName();
+                        }
+                      }))
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_entitlements) -->
+          The entitlements file required for device builds of watch extension.
+
+          See
+          <a href="https://developer.apple.com/library/mac/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/AboutEntitlements.html">the apple documentation</a>
+          for more information. If absent, the default entitlements from the
+          provisioning profile will be used.
+          <p>
+          The following variables are substituted as per
+          <a href="https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html">their definitions in Apple's documentation</a>:
+          $(AppIdentifierPrefix) and $(CFBundleIdentifier).
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_EXT_ENTITLEMENTS_ATTR, LABEL)
+              .allowedFileTypes(ENTITLEMENTS_TYPE))
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_families) -->
+          The device families to which the watch extension is targeted.
+
+          This is known as the <code>TARGETED_DEVICE_FAMILY</code> build setting
+          in Xcode project files. It is a list of one or more of the strings
+          <code>"iphone"</code> and <code>"ipad"</code>.
+
+          <p>By default this is set to <code>"iphone"</code>, if explicitly specified may not be
+          empty.</p>
+          <p>The watch application is always built for <code>"watch"</code> for device builds and
+          <code>"iphone, watch"</code> for simulator builds.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr(WATCH_EXT_FAMILIES_ATTR, STRING_LIST)
+                  .value(ImmutableList.of(TargetDeviceFamily.IPHONE.getNameInRule())))
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_infoplists) -->
+           Infoplist files to be merged. The merged output corresponds to <i>appname</i>-Info.plist
+           in Xcode projects.  Duplicate keys between infoplist files will cause an error if
+           and only if the values conflict.  If both <code>infoplist</code> and
+           <code>infoplists</code> are specified, the files defined in both attributes will be used.
+           Blaze will perform variable substitution on the plist files for the following values:
+           <ul>
+             <li><code>${EXECUTABLE_NAME}</code>: The name of the executable generated and included
+                in the bundle by blaze, which can be used as the value for
+                <code>CFBundleExecutable</code> within the plist.
+             <li><code>${BUNDLE_NAME}</code>: This target's name and bundle suffix (.bundle or .app)
+                in the form<code><var>name</var></code>.<code>suffix</code>.
+             <li><code>${PRODUCT_NAME}</code>: This target's name.
+          </ul>
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_EXT_INFOPLISTS_ATTR, BuildType.LABEL_LIST).allowedFileTypes(PLIST_TYPE))
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_provisioning_profile) -->
+          The provisioning profile (.mobileprovision file) to use when bundling
+          the watch extension.
+
+          This is only used for non-simulator builds.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr(WATCH_EXT_PROVISIONING_PROFILE_ATTR, LABEL)
+                  .singleArtifact()
+                  .allowedFileTypes(FileType.of(".mobileprovision")))
+          .add(
+              attr(WATCH_EXT_DEFAULT_PROVISIONING_PROFILE_ATTR, LABEL)
+                  .singleArtifact()
+                  .allowedFileTypes(FileType.of(".mobileprovision"))
+                  .value(
+                      new LateBoundLabel<BuildConfiguration>(ObjcConfiguration.class) {
+                        @Override
+                        public Label getDefault(Rule rule, AttributeMap attributes,
+                            BuildConfiguration configuration) {
+                          AppleConfiguration appleConfiguration =
+                              configuration.getFragment(AppleConfiguration.class);
+                          if (appleConfiguration.getBundlingPlatform() != Platform.IOS_DEVICE) {
+                            return null;
+                          }
+                          if (rule.isAttributeValueExplicitlySpecified(
+                              WATCH_EXT_PROVISIONING_PROFILE_ATTR)) {
+                            return null;
+                          }
+                          return appleConfiguration.getDefaultProvisioningProfileLabel();
+                        }
+                      }))
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_resources) -->
+          Files to include in the final watch extension bundle.
+
+          They are not processed or compiled in any way besides the processing
+          done by the rules that actually generate them. These files are placed
+          in the root of the bundle (e.g. Foo.app/...) in most cases.
+          However, if they appear to be localized (i.e. are contained in a
+          directory called *.lproj), they will be placed in a directory of the
+          same name in the app bundle.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_EXT_RESOURCES_ATTR, LABEL_LIST).legacyAllowAnyFileType()
+              .direct_compile_time_input())
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_structured_resources)-->
+          Files to include in the final watch extension bundle.
+
+          They are not processed or compiled in any way besides the processing
+          done by the rules that actually generate them. In differences to
+          <code>resources</code> these files are placed in the bundle root in
+          the same structure passed to this argument, so
+          <code>["res/foo.png"]</code> will end up in
+          <code>Foo.app/res/foo.png</code>.
+          <p>Note that in the generated XCode project file, all files in the top directory of
+          the specified files will be included in the Xcode-generated app bundle. So
+          specifying <code>["res/foo.png"]</code> will lead to the inclusion of all files in
+          directory <code>res</code>.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_EXT_STRUCTURED_RESOURCES_ATTR, LABEL_LIST)
+              .legacyAllowAnyFileType()
+              .direct_compile_time_input())
+          /* <!-- #BLAZE_RULE($watch_extension_bundle_rule).ATTRIBUTE(ext_strings) -->
+          Files which are plists of strings, often localizable to be added to watch extension.
+
+          These files are converted to binary plists (if they are not already)
+          and placed in the bundle root of the final package. If this file's
+          immediate containing directory is named *.lproj (e.g. en.lproj,
+          Base.lproj), it will be placed under a directory of that name in the
+          final bundle. This allows for localizable strings.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_EXT_STRINGS_ATTR, LABEL_LIST)
+              .allowedFileTypes(STRINGS_TYPE)
+              .direct_compile_time_input())
+            .build();
+    }
+
+    @Override
+    public Metadata getMetadata() {
+      return RuleDefinition.Metadata.builder()
+          .name("$watch_extension_bundle_rule")
+          .type(RuleClassType.ABSTRACT)
+          .ancestors(
+              AppleToolchain.RequiresXcodeConfigRule.class,
+              ResourceToolsRule.class,
+              ReleaseBundlingToolsRule.class,
+              XcrunRule.class)
+          .build();
+    }
+  }
+
+  /**
+   * Attributes for {@code apple_watch*} rules that creates a watch application bundle.
+   */
+  public static class WatchApplicationBundleRule implements RuleDefinition {
+    static final String WATCH_APP_NAME_ATTR = "app_name";
+    static final String WATCH_APP_ICON_ATTR = "app_icon";
+    static final String WATCH_APP_BUNDLE_ID_ATTR = "app_bundle_id";
+    static final String WATCH_APP_DEFAULT_PROVISIONING_PROFILE_ATTR =
+        ":default_app_provisioning_profile";
+    static final String WATCH_APP_ENTITLEMENTS_ATTR = "app_entitlements";
+    static final String WATCH_APP_PROVISIONING_PROFILE_ATTR = "app_provisioning_profile";
+    static final String WATCH_APP_ASSET_CATALOGS_ATTR = "app_asset_catalogs";
+    static final String WATCH_APP_INFOPLISTS_ATTR = "app_infoplists";
+    static final String WATCH_APP_STORYBOARDS_ATTR = "app_storyboards";
+    static final String WATCH_APP_RESOURCES_ATTR = "app_resources";
+    static final String WATCH_APP_STRUCTURED_RESOURCES_ATTR = "app_structured_resources";
+    static final String WATCH_APP_STRINGS_ATTR = "app_strings";
+
+    @Override
+    public RuleClass build(Builder builder, RuleDefinitionEnvironment env) {
+      return builder
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_name) -->
+          Name of the final watch application binary.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_NAME_ATTR, STRING).mandatory())
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_icon) -->
+          The name of the watch application icon.
+
+          The icon should be in one of the asset catalogs of this target or
+          a (transitive) dependency. In a new project, this is initialized
+          to "AppIcon" by Xcode.
+          <p>
+          If the application icon is not in an asset catalog, do not use this
+          attribute. Instead, add a CFBundleIcons entry to the Info.plist file.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_ICON_ATTR, STRING))
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_entitlements) -->
+          The entitlements file required for device builds of watch application.
+
+          See
+          <a href="https://developer.apple.com/library/mac/documentation/Miscellaneous/Reference/EntitlementKeyReference/Chapters/AboutEntitlements.html">the apple documentation</a>
+          for more information. If absent, the default entitlements from the
+          provisioning profile will be used.
+          <p>
+          The following variables are substituted as per
+          <a href="https://developer.apple.com/library/ios/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html">their definitions in Apple's documentation</a>:
+          $(AppIdentifierPrefix) and $(CFBundleIdentifier).
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_ENTITLEMENTS_ATTR, LABEL)
+              .allowedFileTypes(ENTITLEMENTS_TYPE))
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_asset_catalogs) -->
+          Files that comprise the asset catalogs of the final linked binary.
+
+          Each file must have a containing directory named *.xcassets. This
+          containing directory becomes the root of one of the asset catalogs
+          linked with any binary that depends directly or indirectly on this
+          target.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_ASSET_CATALOGS_ATTR, LABEL_LIST).legacyAllowAnyFileType()
+              .direct_compile_time_input())
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_bundle_id) -->
+          The bundle ID (reverse-DNS path followed by app name) of the watch application binary.
+
+          If specified, it will override the bundle ID specified in the associated plist file. If
+          no bundle ID is specified on either this attribute or in the plist file, a junk value
+          will be used.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr(WATCH_APP_BUNDLE_ID_ATTR, STRING)
+                  .value(
+                      new Attribute.ComputedDefault(WATCH_APP_NAME_ATTR) {
+                        @Override
+                        public Object getDefault(AttributeMap rule) {
+                          // For tests and similar, we don't want to force people to explicitly
+                          // specify throw-away data.
+                          return "example.app." + rule.get(WATCH_APP_NAME_ATTR, STRING);
+                        }
+                      }))
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_infoplists) -->
+           Infoplist files to be merged. The merged output corresponds to <i>appname</i>-Info.plist
+           in Xcode projects.  Duplicate keys between infoplist files will cause an error if
+           and only if the values conflict.  If both <code>infoplist</code> and
+           <code>infoplists</code> are specified, the files defined in both attributes will be used.
+           Blaze will perform variable substitution on the plist files for the following values:
+           <ul>
+             <li><code>${EXECUTABLE_NAME}</code>: The name of the executable generated and included
+                in the bundle by blaze, which can be used as the value for
+                <code>CFBundleExecutable</code> within the plist.
+             <li><code>${BUNDLE_NAME}</code>: This target's name and bundle suffix (.bundle or .app)
+                in the form<code><var>name</var></code>.<code>suffix</code>.
+             <li><code>${PRODUCT_NAME}</code>: This target's name.
+          </ul>
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_INFOPLISTS_ATTR, BuildType.LABEL_LIST).allowedFileTypes(PLIST_TYPE))
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_provisioning_profile)-->
+          The provisioning profile (.mobileprovision file) to use when bundling
+          the watch application.
+
+          This is only used for non-simulator builds.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(
+              attr(WATCH_APP_PROVISIONING_PROFILE_ATTR, LABEL)
+                  .singleArtifact()
+                  .allowedFileTypes(FileType.of(".mobileprovision")))
+          .add(
+              attr(WATCH_APP_DEFAULT_PROVISIONING_PROFILE_ATTR, LABEL)
+                  .singleArtifact()
+                  .allowedFileTypes(FileType.of(".mobileprovision"))
+                  .value(
+                      new LateBoundLabel<BuildConfiguration>(ObjcConfiguration.class) {
+                        @Override
+                        public Label getDefault(Rule rule, AttributeMap attributes,
+                            BuildConfiguration configuration) {
+                          AppleConfiguration appleConfiguration =
+                              configuration.getFragment(AppleConfiguration.class);
+                          if (appleConfiguration.getBundlingPlatform() != Platform.IOS_DEVICE) {
+                            return null;
+                          }
+                          if (rule.isAttributeValueExplicitlySpecified(
+                              WATCH_APP_PROVISIONING_PROFILE_ATTR)) {
+                            return null;
+                          }
+                          return appleConfiguration.getDefaultProvisioningProfileLabel();
+                        }
+                      }))
+          /* <!-- #BLAZE_RULE($objc_resources_rule).ATTRIBUTE(app_storyboards) -->
+          Files which are .storyboard resources for the watch application, possibly
+          localizable.
+
+          These files are compiled and placed in the bundle root of the final package.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_STORYBOARDS_ATTR, LABEL_LIST)
+              .allowedFileTypes(STORYBOARD_TYPE))
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_resources) -->
+          Files to include in the final watch application bundle.
+
+          They are not processed or compiled in any way besides the processing
+          done by the rules that actually generate them. These files are placed
+          in the root of the bundle (e.g. Foo.app/...) in most cases.
+          However, if they appear to be localized (i.e. are contained in a
+          directory called *.lproj), they will be placed in a directory of the
+          same name in the app bundle.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_RESOURCES_ATTR, LABEL_LIST).legacyAllowAnyFileType()
+              .direct_compile_time_input())
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_structured_resources)-->
+          Files to include in the final watch application bundle.
+
+          They are not processed or compiled in any way besides the processing
+          done by the rules that actually generate them. In differences to
+          <code>resources</code> these files are placed in the bundle root in
+          the same structure passed to this argument, so
+          <code>["res/foo.png"]</code> will end up in
+          <code>Foo.app/res/foo.png</code>.
+          <p>Note that in the generated XCode project file, all files in the top directory of
+          the specified files will be included in the Xcode-generated app bundle. So
+          specifying <code>["res/foo.png"]</code> will lead to the inclusion of all files in
+          directory <code>res</code>.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_STRUCTURED_RESOURCES_ATTR, LABEL_LIST)
+              .legacyAllowAnyFileType()
+              .direct_compile_time_input())
+          /* <!-- #BLAZE_RULE($watch_application_bundle_rule).ATTRIBUTE(app_strings) -->
+          Files which are plists of strings, often localizable to be added to watch application.
+
+          These files are converted to binary plists (if they are not already)
+          and placed in the bundle root of the final package. If this file's
+          immediate containing directory is named *.lproj (e.g. en.lproj,
+          Base.lproj), it will be placed under a directory of that name in the
+          final bundle. This allows for localizable strings.
+          <!-- #END_BLAZE_RULE.ATTRIBUTE -->*/
+          .add(attr(WATCH_APP_STRINGS_ATTR, LABEL_LIST)
+              .allowedFileTypes(STRINGS_TYPE)
+              .direct_compile_time_input())
+          .build();
+    }
+    @Override
+    public Metadata getMetadata() {
+      return RuleDefinition.Metadata.builder()
+          .name("$watch_application_bundle_rule")
+          .type(RuleClassType.ABSTRACT)
+          .ancestors(
+              AppleToolchain.RequiresXcodeConfigRule.class,
+              ResourceToolsRule.class,
+              ReleaseBundlingToolsRule.class,
+              XcrunRule.class)
+          .build();
+    }
+  }
 }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcXcodeprojRule.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcXcodeprojRule.java
index 4b6f29cf00..fcb83b0d47 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcXcodeprojRule.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ObjcXcodeprojRule.java
@@ -50,6 +50,8 @@ public class ObjcXcodeprojRule implements RuleDefinition {
                 "ios_application",
                 "ios_extension_binary",
                 "ios_extension",
+                "apple_watch_extension_binary",
+                "apple_watch1_extension",
                 "ios_framework",
                 "ios_framework_binary",
                 "experimental_ios_test",
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundling.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundling.java
index 4a8e560baf..ce72d80618 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundling.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundling.java
@@ -59,7 +59,10 @@ final class ReleaseBundling {
     private final NestedSetBuilder<Artifact> infoplistInputs = NestedSetBuilder.stableOrder();
     private Iterable<Artifact> infoPlistsFromRule;
     private ImmutableSet<TargetDeviceFamily> families;
+    private IntermediateArtifacts intermediateArtifacts;
     private String artifactPrefix;
+    private Artifact entitlements;
+    private Artifact extraEntitlements;
 
     public Builder setIpaArtifact(Artifact ipaArtifact) {
       this.ipaArtifact = ipaArtifact;
@@ -121,6 +124,11 @@ final class ReleaseBundling {
       return this;
     }
 
+    public Builder setIntermediateArtifacts(IntermediateArtifacts intermediateArtifacts) {
+      this.intermediateArtifacts = intermediateArtifacts;
+      return this;
+    }
+
     public Builder setTargetDeviceFamilies(ImmutableSet<TargetDeviceFamily> families) {
       this.families = families;
       return this;
@@ -131,7 +139,18 @@ final class ReleaseBundling {
       return this;
     }
 
+    public Builder setEntitlements(Artifact entitlements) {
+      this.entitlements = entitlements;
+      return this;
+    }
+
+    public Builder setExtraEntitlements(Artifact extraEntitlements) {
+      this.extraEntitlements = extraEntitlements;
+      return this;
+    }
+
     public ReleaseBundling build() {
+      Preconditions.checkNotNull(intermediateArtifacts, "intermediateArtifacts");
       Preconditions.checkNotNull(families, FAMILIES_ATTR);
       return new ReleaseBundling(
           ipaArtifact,
@@ -146,7 +165,10 @@ final class ReleaseBundling {
           infoplistInputs.build(),
           infoPlistsFromRule,
           families,
-          artifactPrefix);
+          intermediateArtifacts,
+          artifactPrefix,
+          entitlements,
+          extraEntitlements);
     }
   }
 
@@ -203,6 +225,10 @@ final class ReleaseBundling {
         .setProvisioningProfile(provisioningProfile)
         .setProvisioningProfileAttributeName(PROVISIONING_PROFILE_ATTR)
         .setTargetDeviceFamilies(families)
+        .setIntermediateArtifacts(ObjcRuleClasses.intermediateArtifacts(ruleContext))
+        .setEntitlements(ruleContext.getPrerequisiteArtifact("entitlements", Mode.TARGET))
+        .setExtraEntitlements(
+            ruleContext.getPrerequisiteArtifact(":extra_entitlements", Mode.TARGET))
         .build();
   }
 
@@ -220,8 +246,11 @@ final class ReleaseBundling {
   private final String provisioningProfileAttributeName;
   private final NestedSet<Artifact> infoplistInputs;
   private final ImmutableSet<TargetDeviceFamily> families;
+  private final IntermediateArtifacts intermediateArtifacts;
   private final Iterable<Artifact> infoPlistsFromRule;
   private final String artifactPrefix;
+  private final Artifact entitlements;
+  private final Artifact extraEntitlements;
 
   private ReleaseBundling(
       Artifact ipaArtifact,
@@ -236,7 +265,10 @@ final class ReleaseBundling {
       NestedSet<Artifact> infoplistInputs,
       Iterable<Artifact> infoPlistsFromRule,
       ImmutableSet<TargetDeviceFamily> families,
-      String artifactPrefix) {
+      IntermediateArtifacts intermediateArtifacts,
+      String artifactPrefix,
+      Artifact entitlements,
+      Artifact extraEntitlements) {
     this.ipaArtifact = Preconditions.checkNotNull(ipaArtifact);
     this.bundleId = bundleId;
     this.primaryBundleId = primaryBundleId;
@@ -250,7 +282,10 @@ final class ReleaseBundling {
     this.infoplistInputs = Preconditions.checkNotNull(infoplistInputs);
     this.infoPlistsFromRule = infoPlistsFromRule;
     this.families = Preconditions.checkNotNull(families);
+    this.intermediateArtifacts = Preconditions.checkNotNull(intermediateArtifacts);
     this.artifactPrefix = artifactPrefix;
+    this.entitlements = entitlements;
+    this.extraEntitlements = extraEntitlements;
   }
 
   /**
@@ -326,6 +361,13 @@ final class ReleaseBundling {
   }
 
   /**
+   * Returns {@link IntermediateArtifacts} used to create this bundle.
+   */
+  public IntermediateArtifacts getIntermediateArtifacts() {
+    return intermediateArtifacts;
+  }
+
+  /**
    * Returns the name of the attribute which is used to specifiy the provisioning profile.
    */
   public String getProvisioningProfileAttrName() {
@@ -348,4 +390,20 @@ final class ReleaseBundling {
   public String getArtifactPrefix() {
     return artifactPrefix;
   }
+
+  /**
+   * Returns an {@link Artifact} containing the entitlements used to sign this bundle for
+   * non-simulator builds; can be null.
+   */
+  public Artifact getEntitlements() {
+    return entitlements;
+  }
+
+  /**
+   * Returns an {@link Artifact} containing the extra entitlements passed via command line that is
+   * used to sign this bundle for non-simulator builds; can be null.
+   */
+  public Artifact getExtraEntitlements() {
+    return extraEntitlements;
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
index 617300ecab..8b15f7ac6a 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingSupport.java
@@ -18,8 +18,6 @@ import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.devtools.build.lib.packages.ImplicitOutputsFunction.fromTemplates;
 import static com.google.devtools.build.lib.rules.objc.ObjcProvider.Flag.USES_SWIFT;
 import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.ReleaseBundlingRule.APP_ICON_ATTR;
-import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.ReleaseBundlingRule.ENTITLEMENTS_ATTR;
-import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.ReleaseBundlingRule.EXTRA_ENTITLEMENTS_ATTR;
 import static com.google.devtools.build.lib.rules.objc.TargetDeviceFamily.UI_DEVICE_FAMILY_VALUES;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -172,7 +170,7 @@ public final class ReleaseBundlingSupport {
     this.ruleContext = ruleContext;
     this.objcProvider = objcProvider;
     this.releaseBundling = releaseBundling;
-    this.intermediateArtifacts = ObjcRuleClasses.intermediateArtifacts(ruleContext);
+    this.intermediateArtifacts = releaseBundling.getIntermediateArtifacts();
     this.bundling = bundling(ruleContext, objcProvider, bundleDirFormat, bundleName,
         bundleMinimumOsVersion);
     bundleSupport = new BundleSupport(ruleContext, bundling, extraActoolArgs());
@@ -520,12 +518,12 @@ public final class ReleaseBundlingSupport {
    * <p>Finally, if an entitlements file was provided via {@code --extra_entitlements} it is merged
    * into the substituted entitlements.
    */
-  private void registerEntitlementsActions() throws InterruptedException {
+  private void registerEntitlementsActions() {
     Artifact teamPrefixFile =
         intermediateArtifacts.appendExtensionForEntitlementArtifact(".team_prefix_file");
     registerExtractTeamPrefixAction(teamPrefixFile);
 
-    Artifact entitlementsNeedingSubstitution = attributes.entitlements();
+    Artifact entitlementsNeedingSubstitution = releaseBundling.getEntitlements();
     if (entitlementsNeedingSubstitution == null) {
       entitlementsNeedingSubstitution =
           intermediateArtifacts.appendExtensionForEntitlementArtifact(
@@ -534,10 +532,11 @@ public final class ReleaseBundlingSupport {
     }
 
     Artifact substitutedEntitlements = intermediateArtifacts.entitlements();
-    if (attributes.extraEntitlements() != null) {
+    if (releaseBundling.getExtraEntitlements() != null) {
       substitutedEntitlements =
           intermediateArtifacts.appendExtensionForEntitlementArtifact(".substituted");
-      registerMergeEntitlementsAction(substitutedEntitlements, attributes.extraEntitlements());
+      registerMergeEntitlementsAction(substitutedEntitlements,
+          releaseBundling.getExtraEntitlements());
     }
 
     registerEntitlementsVariableSubstitutionAction(
@@ -760,6 +759,12 @@ public final class ReleaseBundlingSupport {
   }
 
   private void registerCombineArchitecturesAction() {
+    // Skip combining binaries when building for watch as there is only one stub binary and it
+    // it should not be corrupted when combining.
+    if (bundleSupport.isBuildingForWatch()) {
+      return;
+    }
+
     Artifact resultingLinkedBinary = intermediateArtifacts.combinedArchitectureBinary();
     NestedSet<Artifact> linkedBinaries = linkedBinaries();
 
@@ -802,7 +807,12 @@ public final class ReleaseBundlingSupport {
     }
 
     // Convert names to a sequence containing "1" and/or "2" for iPhone and iPad, respectively.
-    ImmutableSet<TargetDeviceFamily> families = bundleSupport.targetDeviceFamilies();
+    ImmutableSet<TargetDeviceFamily> families;
+    if (bundleSupport.isBuildingForWatch()) {
+      families = ImmutableSet.of(TargetDeviceFamily.WATCH);
+    } else {
+      families = bundleSupport.targetDeviceFamilies();
+    }
     Iterable<Integer> familyIndexes =
         families.isEmpty() ? ImmutableList.<Integer>of() : UI_DEVICE_FAMILY_VALUES.get(families);
     buildSettings.add(XcodeprojBuildSetting.newBuilder()
@@ -810,7 +820,7 @@ public final class ReleaseBundlingSupport {
         .setValue(Joiner.on(',').join(familyIndexes))
         .build());
 
-    Artifact entitlements = attributes.entitlements();
+    Artifact entitlements = releaseBundling.getEntitlements();
     if (entitlements != null) {
       buildSettings.add(XcodeprojBuildSetting.newBuilder()
           .setName("CODE_SIGN_ENTITLEMENTS")
@@ -1163,16 +1173,6 @@ public final class ReleaseBundlingSupport {
       return ruleContext.getExecutablePrerequisite("ipa_post_processor", Mode.TARGET);
     }
 
-    @Nullable
-    Artifact entitlements() {
-      return ruleContext.getPrerequisiteArtifact(ENTITLEMENTS_ATTR, Mode.TARGET);
-    }
-
-    @Nullable
-    Artifact extraEntitlements() {
-      return ruleContext.getPrerequisiteArtifact(EXTRA_ENTITLEMENTS_ATTR, Mode.TARGET);
-    }
-
     NestedSet<? extends Artifact> dependentLinkedBinaries() {
       if (ruleContext.attributes().getAttributeDefinition("binary") == null) {
         return NestedSetBuilder.emptySet(Order.STABLE_ORDER);
@@ -1330,7 +1330,7 @@ public final class ReleaseBundlingSupport {
      * transition may exist with the same value in a single Bazel invocation.
      */
     enum ConfigurationDistinguisher {
-      IOS_EXTENSION, IOS_APPLICATION, FRAMEWORK, UNKNOWN
+      IOS_EXTENSION, IOS_APPLICATION, FRAMEWORK, UNKNOWN, WATCH_OS1_EXTENSION
     }
   }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
index 373271a163..4a53915177 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/ReleaseBundlingTargetFactory.java
@@ -62,6 +62,7 @@ public abstract class ReleaseBundlingTargetFactory implements RuleConfiguredTarg
 
   @Override
   public ConfiguredTarget create(RuleContext ruleContext) throws InterruptedException {
+    validateAttributes(ruleContext);
     ObjcCommon common = common(ruleContext);
 
     XcodeProvider.Builder xcodeProviderBuilder = new XcodeProvider.Builder();
@@ -108,6 +109,12 @@ public abstract class ReleaseBundlingTargetFactory implements RuleConfiguredTarg
   }
 
   /**
+   * Validates application-related attributes set on this rule and registers any errors with the
+   * rule context. Default implemenation does nothing; subclasses may override it.
+   */
+  protected void validateAttributes(RuleContext ruleContext) {}
+
+  /**
    * Returns the minimum OS version this bundle's plist and resources should be generated for
    * (<b>not</b> the minimum OS version its binary is compiled with, that needs to be set in the
    * configuration).
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/TargetDeviceFamily.java b/src/main/java/com/google/devtools/build/lib/rules/objc/TargetDeviceFamily.java
index 511adbd3f4..5074a6ee64 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/TargetDeviceFamily.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/TargetDeviceFamily.java
@@ -29,7 +29,7 @@ import java.util.Set;
  * Possible values in the {@code TARGETED_DEVICE_FAMILY} build setting.
  */
 public enum TargetDeviceFamily {
-  IPAD, IPHONE;
+  IPAD, IPHONE, WATCH;
 
   /**
    * An exception that indicates the name of a device family was not recognized or is somehow
@@ -59,8 +59,11 @@ public enum TargetDeviceFamily {
       ImmutableMap.<Set<TargetDeviceFamily>, List<Integer>>builder()
           .put(ImmutableSet.of(TargetDeviceFamily.IPHONE), ImmutableList.of(1))
           .put(ImmutableSet.of(TargetDeviceFamily.IPAD), ImmutableList.of(2))
+          .put(ImmutableSet.of(TargetDeviceFamily.WATCH), ImmutableList.of(4))
           .put(ImmutableSet.of(TargetDeviceFamily.IPHONE, TargetDeviceFamily.IPAD),
               ImmutableList.of(1, 2))
+          .put(ImmutableSet.of(TargetDeviceFamily.IPHONE, TargetDeviceFamily.WATCH),
+              ImmutableList.of(1, 4))
           .build();
 
   /**
@@ -71,7 +74,7 @@ public enum TargetDeviceFamily {
   }
 
   private static final ImmutableBiMap<TargetDeviceFamily, String> BY_NAME_IN_RULE =
-      ImmutableBiMap.of(IPAD, "ipad", IPHONE, "iphone");
+      ImmutableBiMap.of(IPAD, "ipad", IPHONE, "iphone", WATCH, "watch");
 
   /**
    * Converts a sequence containing the strings returned by {@link #getNameInRule()} to a set of
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/WatchApplicationSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchApplicationSupport.java
new file mode 100644
index 0000000000..1bfb602e2a
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchApplicationSupport.java
@@ -0,0 +1,352 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.ASSET_CATALOG;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.BUNDLE_FILE;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.GENERAL_RESOURCE_DIR;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.GENERAL_RESOURCE_FILE;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STORYBOARD;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STRINGS;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.XCASSETS_DIR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_ASSET_CATALOGS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_BUNDLE_ID_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_DEFAULT_PROVISIONING_PROFILE_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_ENTITLEMENTS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_ICON_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_INFOPLISTS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_PROVISIONING_PROFILE_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_RESOURCES_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_STORYBOARDS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_STRINGS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchApplicationBundleRule.WATCH_APP_STRUCTURED_RESOURCES_ATTR;
+
+import com.google.common.base.Joiner;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.LabelSyntaxException;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+import com.google.devtools.build.lib.rules.apple.Platform;
+import com.google.devtools.build.lib.rules.objc.ObjcProvider.Builder;
+import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.LinkedBinary;
+import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition.ConfigurationDistinguisher;
+import com.google.devtools.build.lib.rules.objc.WatchUtils.WatchOSVersion;
+import com.google.devtools.build.lib.syntax.Type;
+import com.google.devtools.build.xcode.xcodegen.proto.XcodeGenProtos.XcodeprojBuildSetting;
+
+import javax.annotation.Nullable;
+
+/**
+ * Contains support methods to build watch application bundle - does normal bundle processing -
+ * resources, plists and creates a final (signed if necessary) bundle.
+ */
+final class WatchApplicationSupport {
+
+  private final RuleContext ruleContext;
+  private final WatchOSVersion watchOSVersion;
+  private final ImmutableSet<Attribute> dependencyAttributes;
+  private final String bundleName;
+  private final IntermediateArtifacts intermediateArtifacts;
+  private final Attributes attributes;
+  private final Artifact ipaArtifact;
+  private final String artifactPrefix;
+  private final ConfigurationDistinguisher configurationDistinguisher;
+
+  WatchApplicationSupport(RuleContext ruleContext, WatchOSVersion watchOSVersion,
+      ImmutableSet<Attribute> dependencyAttributes, IntermediateArtifacts intermediateArtifacts,
+      String bundleName, Artifact ipaArtifact, String artifactPrefix,
+      ConfigurationDistinguisher configurationDistinguisher) {
+    this.ruleContext = ruleContext;
+    this.watchOSVersion = watchOSVersion;
+    this.dependencyAttributes = dependencyAttributes;
+    this.intermediateArtifacts = intermediateArtifacts;
+    this.bundleName = bundleName;
+    this.ipaArtifact = ipaArtifact;
+    this.artifactPrefix = artifactPrefix;
+    this.attributes = new Attributes(ruleContext);
+    this.configurationDistinguisher = configurationDistinguisher;
+  }
+
+  void createBundle(XcodeProvider.Builder xcodeProviderBuilder,
+      ObjcProvider.Builder objcProviderBuilder, NestedSetBuilder<Artifact> filesToBuild)
+          throws InterruptedException {
+    // Add common watch settings.
+    WatchUtils.addXcodeSettings(ruleContext, xcodeProviderBuilder);
+
+    // Add watch application specific xcode settings.
+    addXcodeSettings(xcodeProviderBuilder);
+
+    registerActions();
+
+    ObjcProvider objcProvider = objcProvider(objcProviderBuilder);
+    ReleaseBundling.Builder releaseBundling = new ReleaseBundling.Builder()
+        .setIpaArtifact(ipaArtifact)
+        .setBundleId(attributes.bundleId())
+        .setAppIcon(attributes.appIcon())
+        .setProvisioningProfile(attributes.provisioningProfile())
+        .setProvisioningProfileAttributeName(WATCH_APP_PROVISIONING_PROFILE_ATTR)
+        .setTargetDeviceFamilies(families())
+        .setIntermediateArtifacts(intermediateArtifacts)
+        .setInfoPlistsFromRule(attributes.infoPlists())
+        .setArtifactPrefix(artifactPrefix)
+        .setEntitlements(attributes.entitlements());
+
+    if (attributes.isBundleIdExplicitySpecified()) {
+      releaseBundling.setPrimaryBundleId(attributes.bundleId());
+    } else {
+      releaseBundling.setFallbackBundleId(attributes.bundleId());
+    }
+
+    new ReleaseBundlingSupport(
+            ruleContext,
+            objcProvider,
+            LinkedBinary.DEPENDENCIES_ONLY,
+            ReleaseBundlingSupport.APP_BUNDLE_DIR_FORMAT,
+            bundleName,
+            WatchUtils.determineMinimumOsVersion(
+                ObjcRuleClasses.objcConfiguration(ruleContext).getMinimumOs()),
+            releaseBundling.build())
+        .registerActions(DsymOutputType.APP)
+        .addXcodeSettings(xcodeProviderBuilder)
+        .addFilesToBuild(filesToBuild, DsymOutputType.APP)
+        .validateResources()
+        .validateAttributes();
+
+    XcodeSupport xcodeSupport = new XcodeSupport(ruleContext, intermediateArtifacts,
+        labelForWatchApplication())
+        .addXcodeSettings(xcodeProviderBuilder, objcProvider,
+            watchOSVersion.getApplicationXcodeProductType(),
+            ruleContext.getFragment(AppleConfiguration.class).getIosCpu(),
+            configurationDistinguisher);
+
+    for (Attribute attribute : dependencyAttributes) {
+      xcodeSupport.addDependencies(xcodeProviderBuilder, attribute);
+    }
+  }
+
+  /**
+   * Returns the {@link TargetDeviceFamily} that the watch application bundle is targeting.
+   * For simulator builds, this returns a set of {@code TargetDeviceFamily.IPHONE} and
+   * {@code TargetDeviceFamily.WATCH} and for non-simulator builds, this returns
+   * {@code TargetDeviceFamily.WATCH}.
+   */
+  private ImmutableSet<TargetDeviceFamily> families() {
+    Platform platform = ruleContext.getFragment(AppleConfiguration.class).getBundlingPlatform();
+    if (platform == Platform.IOS_DEVICE) {
+      return ImmutableSet.of(TargetDeviceFamily.WATCH);
+    } else {
+      return ImmutableSet.of(TargetDeviceFamily.IPHONE, TargetDeviceFamily.WATCH);
+    }
+  }
+
+  /**
+   * Adds watch application specific xcode settings - TARGETED_DEVICE_FAMILY is set to "1, 4"
+   * for enabling building for simulator.
+   */
+  private void addXcodeSettings(XcodeProvider.Builder xcodeProviderBuilder) {
+    xcodeProviderBuilder.addMainTargetXcodeprojBuildSettings(ImmutableList.of(
+        XcodeprojBuildSetting.newBuilder()
+        .setName("TARGETED_DEVICE_FAMILY[sdk=iphonesimulator*]")
+        .setValue(Joiner.on(',').join(TargetDeviceFamily.UI_DEVICE_FAMILY_VALUES.get(
+            families())))
+        .build()));
+  }
+
+  /**
+   * Registers actions to copy WatchKit stub binary at
+   * $(SDK_ROOT)/Library/Application Support/WatchKit/WK as bundle binary and as stub resource.
+   *
+   * For example, for a bundle named "Foo.app", the contents will be,
+   *    - Foo.app/Foo (WK stub as binary)
+   *    - Foo.app/_WatchKitStub/WK  (WK stub as resource)
+   */
+  private void registerActions() {
+    Artifact watchKitStubZip = watchKitStubZip();
+    String workingDirectory = watchKitStubZip.getExecPathString()
+        .substring(0, watchKitStubZip.getExecPathString().lastIndexOf('/'));
+    String watchKitStubBinaryPath = workingDirectory + "/" + bundleName;
+    String watchKitStubResourcePath = workingDirectory + "/_WatchKitStub";
+
+    ImmutableList<String> command = ImmutableList.of(
+        // 1. Copy WK stub as binary
+        String.format("cp %s %s", WatchUtils.WATCH_KIT_STUB_PATH, watchKitStubBinaryPath),
+        "&&",
+        // 2. Copy WK stub as bundle resource.
+        "mkdir -p " + watchKitStubResourcePath,
+        "&&",
+        String.format("cp %s %s", WatchUtils.WATCH_KIT_STUB_PATH, watchKitStubResourcePath),
+         // 3. Zip them.
+        "&&",
+        "cd " + workingDirectory,
+        "&&",
+        String.format(
+            "/usr/bin/zip -q -r -0 %s %s",
+            watchKitStubZip.getFilename(),
+            Joiner.on(" ").join(ImmutableList.of("_WatchKitStub", bundleName))));
+
+    ruleContext.registerAction(ObjcRuleClasses.spawnAppleEnvActionBuilder(ruleContext,
+        ruleContext.getFragment(AppleConfiguration.class).getBundlingPlatform())
+        .setProgressMessage(
+            "Copying WatchKit binary and stub resource: " + ruleContext.getLabel())
+        .setShellCommand(ImmutableList.of("/bin/bash", "-c", Joiner.on(" ").join(command)))
+        .addOutput(watchKitStubZip)
+        .build(ruleContext));
+  }
+
+  private ObjcProvider objcProvider(Builder objcProviderBuilder) {
+    // Add all resource files applicable to watch application from dependency providers.
+    for (Attribute attribute : dependencyAttributes) {
+      Iterable<ObjcProvider> dependencyObjcProviders = ruleContext.getPrerequisites(
+          attribute.getName(), attribute.getAccessMode(), ObjcProvider.class);
+      for (ObjcProvider dependencyObjcProvider : dependencyObjcProviders) {
+        objcProviderBuilder.addTransitiveAndPropagate(GENERAL_RESOURCE_FILE,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(GENERAL_RESOURCE_DIR,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(BUNDLE_FILE,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(XCASSETS_DIR,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(ASSET_CATALOG,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(STRINGS,
+            dependencyObjcProvider);
+        objcProviderBuilder.addTransitiveAndPropagate(STORYBOARD,
+            dependencyObjcProvider);
+      }
+    }
+    // Add zip containing WatchKit stubs.
+    objcProviderBuilder.add(ObjcProvider.MERGE_ZIP, watchKitStubZip());
+
+    // Add resource files.
+    objcProviderBuilder.addAll(GENERAL_RESOURCE_FILE, attributes.storyboards())
+      .addAll(GENERAL_RESOURCE_FILE, attributes.resources())
+      .addAll(GENERAL_RESOURCE_FILE, attributes.strings())
+      .addAll(GENERAL_RESOURCE_DIR,
+          ObjcCommon.xcodeStructuredResourceDirs(attributes.structuredResources()))
+      .addAll(BUNDLE_FILE, BundleableFile.flattenedRawResourceFiles(attributes.resources()))
+      .addAll(
+          BUNDLE_FILE,
+          BundleableFile.structuredRawResourceFiles(attributes.structuredResources()))
+      .addAll(XCASSETS_DIR, ObjcCommon.uniqueContainers(attributes.assetCatalogs(),
+          ObjcCommon.ASSET_CATALOG_CONTAINER_TYPE))
+      .addAll(ASSET_CATALOG, attributes.assetCatalogs())
+      .addAll(STRINGS, attributes.strings())
+      .addAll(STORYBOARD, attributes.storyboards());
+
+    return objcProviderBuilder.build();
+  }
+
+  private Label labelForWatchApplication()
+      throws InterruptedException {
+    try {
+      return Label.create(ruleContext.getLabel().getPackageName(), bundleName);
+    } catch (LabelSyntaxException labelSyntaxException) {
+        throw new InterruptedException("Exception while creating target label for watch "
+            + "appplication " + labelSyntaxException);
+    }
+  }
+
+  /**
+   * Returns a zip {@link Artifact} containing stub binary and stub resource that are to be added
+   * to the bundle.
+   */
+  private Artifact watchKitStubZip() {
+    return ruleContext.getRelatedArtifact(
+        ruleContext.getUniqueDirectory("_watch"), "/WatchKitStub.zip");
+  }
+
+  /**
+   * Rule attributes used for creating watch application bundle.
+   */
+  private static class Attributes {
+    private final RuleContext ruleContext;
+
+    private Attributes(RuleContext ruleContext) {
+      this.ruleContext = ruleContext;
+    }
+
+    @Nullable
+    String appIcon() {
+      return Strings.emptyToNull(ruleContext.attributes().get(WATCH_APP_ICON_ATTR, Type.STRING));
+    }
+
+    @Nullable
+    Artifact provisioningProfile() {
+      Artifact explicitProvisioningProfile =
+          getPrerequisiteArtifact(WATCH_APP_PROVISIONING_PROFILE_ATTR);
+      if (explicitProvisioningProfile != null) {
+        return explicitProvisioningProfile;
+      }
+      return getPrerequisiteArtifact(WATCH_APP_DEFAULT_PROVISIONING_PROFILE_ATTR);
+    }
+
+    String bundleId() {
+      Preconditions.checkState(!Strings.isNullOrEmpty(
+          ruleContext.attributes().get(WATCH_APP_BUNDLE_ID_ATTR, Type.STRING)),
+          "requires a bundle_id value");
+      return ruleContext.attributes().get(WATCH_APP_BUNDLE_ID_ATTR, Type.STRING);
+    }
+
+    ImmutableList<Artifact> infoPlists() {
+      return getPrerequisiteArtifacts(WATCH_APP_INFOPLISTS_ATTR);
+    }
+
+    ImmutableList<Artifact> assetCatalogs() {
+      return getPrerequisiteArtifacts(WATCH_APP_ASSET_CATALOGS_ATTR);
+    }
+
+    ImmutableList<Artifact> strings() {
+      return getPrerequisiteArtifacts(WATCH_APP_STRINGS_ATTR);
+    }
+
+    ImmutableList<Artifact> storyboards() {
+      return getPrerequisiteArtifacts(WATCH_APP_STORYBOARDS_ATTR);
+    }
+
+    ImmutableList<Artifact> resources() {
+      return getPrerequisiteArtifacts(WATCH_APP_RESOURCES_ATTR);
+    }
+
+    ImmutableList<Artifact> structuredResources() {
+      return getPrerequisiteArtifacts(WATCH_APP_STRUCTURED_RESOURCES_ATTR);
+    }
+
+    @Nullable
+    Artifact entitlements() {
+      return getPrerequisiteArtifact(WATCH_APP_ENTITLEMENTS_ATTR);
+    }
+
+    private boolean isBundleIdExplicitySpecified() {
+      return ruleContext.attributes().isAttributeValueExplicitlySpecified(WATCH_APP_BUNDLE_ID_ATTR);
+    }
+
+    private ImmutableList<Artifact> getPrerequisiteArtifacts(String attribute) {
+      return ruleContext.getPrerequisiteArtifacts(attribute, Mode.TARGET).list();
+    }
+
+    @Nullable
+    private Artifact getPrerequisiteArtifact(String attribute) {
+      return ruleContext.getPrerequisiteArtifact(attribute, Mode.TARGET);
+    }
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/WatchExtensionSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchExtensionSupport.java
new file mode 100644
index 0000000000..1aa561ffe7
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchExtensionSupport.java
@@ -0,0 +1,301 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.BUNDLE_FILE;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.GENERAL_RESOURCE_DIR;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.GENERAL_RESOURCE_FILE;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.MERGE_ZIP;
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.STRINGS;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.BundlingRule.FAMILIES_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_BUNDLE_ID_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_DEFAULT_PROVISIONING_PROFILE_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_ENTITLEMENTS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_FAMILIES_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_INFOPLISTS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_PROVISIONING_PROFILE_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_RESOURCES_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_STRINGS_ATTR;
+import static com.google.devtools.build.lib.rules.objc.ObjcRuleClasses.WatchExtensionBundleRule.WATCH_EXT_STRUCTURED_RESOURCES_ATTR;
+
+import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.RuleConfiguredTarget.Mode;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.analysis.actions.FileWriteAction;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+import com.google.devtools.build.lib.rules.objc.ObjcProvider.Builder;
+import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.LinkedBinary;
+import com.google.devtools.build.lib.rules.objc.ReleaseBundlingSupport.SplitArchTransition.ConfigurationDistinguisher;
+import com.google.devtools.build.lib.rules.objc.TargetDeviceFamily.InvalidFamilyNameException;
+import com.google.devtools.build.lib.rules.objc.TargetDeviceFamily.RepeatedFamilyNameException;
+import com.google.devtools.build.lib.rules.objc.WatchUtils.WatchOSVersion;
+import com.google.devtools.build.lib.syntax.Type;
+
+import com.dd.plist.NSDictionary;
+import com.dd.plist.NSObject;
+
+import java.util.List;
+
+import javax.annotation.Nullable;
+
+/**
+ * Contains support methods to build watch extension bundle - does normal bundle processing -
+ * compiling and linking the binary, resources, plists and creates a final
+ * (signed if necessary) bundle.
+ */
+public class WatchExtensionSupport {
+
+  private final RuleContext ruleContext;
+  private final WatchOSVersion watchOSVersion;
+  private final ImmutableSet<Attribute> dependencyAttributes;
+  private final IntermediateArtifacts intermediateArtifacts;
+  private final String bundleName;
+  private final Artifact ipaArtifact;
+  private final Artifact watchApplicationBundle;
+  private final Attributes attributes;
+  private final XcodeProvider watchApplicationXcodeProvider;
+  private final ConfigurationDistinguisher configurationDistinguisher;
+
+  WatchExtensionSupport(RuleContext ruleContext,
+      WatchOSVersion watchOSVersion,
+      ImmutableSet<Attribute> dependencyAttributes,
+      IntermediateArtifacts intermediateArtifacts,
+      String bundleName,
+      Artifact ipaArtifact,
+      Artifact watchApplicationBundle,
+      XcodeProvider watchApplicationXcodeProvider,
+      ConfigurationDistinguisher configurationDistinguisher) {
+    this.ruleContext = ruleContext;
+    this.watchOSVersion = watchOSVersion;
+    this.dependencyAttributes = dependencyAttributes;
+    this.intermediateArtifacts = intermediateArtifacts;
+    this.bundleName = bundleName;
+    this.ipaArtifact = ipaArtifact;
+    this.attributes = new Attributes(ruleContext);
+    if (WatchUtils.isBuildingForWatchOS1Version(watchOSVersion)) {
+      checkNotNull(watchApplicationXcodeProvider);
+      checkNotNull(watchApplicationBundle);
+    }
+    this.watchApplicationXcodeProvider = watchApplicationXcodeProvider;
+    this.watchApplicationBundle = watchApplicationBundle;
+    this.configurationDistinguisher = configurationDistinguisher;
+  }
+
+  void createBundle(NestedSetBuilder<Artifact> filesToBuild,
+      ObjcProvider.Builder objcProviderBuilder, XcodeProvider.Builder xcodeProviderBuilder)
+          throws InterruptedException {
+    WatchUtils.addXcodeSettings(ruleContext, xcodeProviderBuilder);
+
+    registerWatchExtensionAutomaticPlistAction();
+
+    ObjcProvider objcProvider = objcProvider(objcProviderBuilder);
+
+    ImmutableSet<TargetDeviceFamily> families = attributes.families();
+
+    if (families.isEmpty()) {
+      ruleContext.attributeError(FAMILIES_ATTR, ReleaseBundling.INVALID_FAMILIES_ERROR);
+    }
+
+    ReleaseBundling.Builder releaseBundling = new ReleaseBundling.Builder()
+        .setIpaArtifact(ipaArtifact)
+        .setBundleId(attributes.bundleId())
+        .setProvisioningProfile(attributes.provisioningProfile())
+        .setProvisioningProfileAttributeName(WATCH_EXT_PROVISIONING_PROFILE_ATTR)
+        .setTargetDeviceFamilies(families)
+        .setIntermediateArtifacts(intermediateArtifacts)
+        .setInfoPlistsFromRule(attributes.infoPlists())
+        .addInfoplistInput(watchExtensionAutomaticPlist())
+        .setEntitlements(attributes.entitlements());
+
+    if (attributes.isBundleIdExplicitySpecified()) {
+      releaseBundling.setPrimaryBundleId(attributes.bundleId());
+    } else {
+      releaseBundling.setFallbackBundleId(attributes.bundleId());
+    }
+
+    ReleaseBundlingSupport releaseBundlingSupport =
+        new ReleaseBundlingSupport(
+            ruleContext,
+            objcProvider,
+            LinkedBinary.DEPENDENCIES_ONLY,
+            ReleaseBundlingSupport.EXTENSION_BUNDLE_DIR_FORMAT,
+            bundleName,
+            WatchUtils.determineMinimumOsVersion(
+                ObjcRuleClasses.objcConfiguration(ruleContext).getMinimumOs()),
+            releaseBundling.build());
+
+    releaseBundlingSupport
+        .registerActions(DsymOutputType.APP)
+        .addXcodeSettings(xcodeProviderBuilder)
+        .addFilesToBuild(filesToBuild, DsymOutputType.APP)
+        .validateResources()
+        .validateAttributes();
+
+    XcodeSupport xcodeSupport = new XcodeSupport(ruleContext)
+        .addFilesToBuild(filesToBuild)
+        .addXcodeSettings(xcodeProviderBuilder, objcProvider,
+            watchOSVersion.getExtensionXcodeProductType(),
+            ruleContext.getFragment(AppleConfiguration.class).getDependencySingleArchitecture(),
+            configurationDistinguisher)
+        .addDummySource(xcodeProviderBuilder);
+
+    for (Attribute attribute : dependencyAttributes) {
+      xcodeSupport.addDependencies(xcodeProviderBuilder, attribute);
+    }
+
+    if (WatchUtils.isBuildingForWatchOS1Version(watchOSVersion)) {
+      // Generate xcodeproj for watch OS 1 extension as the main target with watch application
+      // target as the dependency.
+      xcodeProviderBuilder.addPropagatedDependencies(
+          ImmutableList.of(watchApplicationXcodeProvider));
+      xcodeSupport.registerActions(xcodeProviderBuilder.build());
+    }
+  }
+
+  /**
+   * Registers an action to generate a plist containing entries required for watch extension that
+   * should be added to the merged plist.
+   */
+  private void registerWatchExtensionAutomaticPlistAction() {
+    List<String> uiRequiredDeviceCapabilities = ImmutableList.of("watch-companion");
+    NSDictionary watchExtensionAutomaticEntries = new NSDictionary();
+    watchExtensionAutomaticEntries.put("UIRequiredDeviceCapabilities",
+        NSObject.wrap(uiRequiredDeviceCapabilities.toArray()));
+
+    ruleContext.registerAction(
+        new FileWriteAction(
+            ruleContext.getActionOwner(),
+            watchExtensionAutomaticPlist(),
+            watchExtensionAutomaticEntries.toGnuStepASCIIPropertyList(),
+            /*makeExecutable=*/ false));
+  }
+
+  private Artifact watchExtensionAutomaticPlist() {
+    return ruleContext.getRelatedArtifact(
+        ruleContext.getUniqueDirectory("plists"), "-automatic-watchExtensionInfo.plist");
+  }
+
+  private ObjcProvider objcProvider(Builder objcProviderBuilder) {
+    // Add dependency providers.
+    for (Attribute attribute : dependencyAttributes) {
+      objcProviderBuilder.addTransitiveAndPropagate(
+            ruleContext.getPrerequisites(
+                attribute.getName(), attribute.getAccessMode(), ObjcProvider.class));
+      }
+
+    if (WatchUtils.isBuildingForWatchOS1Version(watchOSVersion)) {
+      // Expose the generated watch application bundle to the extension bundle.
+      objcProviderBuilder.add(MERGE_ZIP, watchApplicationBundle);
+    }
+
+    // Add resource files.
+    objcProviderBuilder.addAll(GENERAL_RESOURCE_FILE, attributes.resources())
+        .addAll(GENERAL_RESOURCE_FILE, attributes.strings())
+        .addAll(GENERAL_RESOURCE_DIR, ObjcCommon.xcodeStructuredResourceDirs(
+            attributes.structuredResources()))
+        .addAll(BUNDLE_FILE, BundleableFile.flattenedRawResourceFiles(attributes.resources()))
+        .addAll(
+            BUNDLE_FILE,
+            BundleableFile.structuredRawResourceFiles(attributes.structuredResources()))
+        .addAll(STRINGS, attributes.strings());
+
+    return objcProviderBuilder.build();
+  }
+
+  /**
+   * Rule attributes used for creating watch application bundle.
+   */
+  private static class Attributes {
+    private final RuleContext ruleContext;
+
+    private Attributes(RuleContext ruleContext) {
+      this.ruleContext = ruleContext;
+    }
+
+    /**
+     * Returns the value of the {@code families} attribute in a form
+     * that is more useful than a list of strings. Returns an empty
+     * set for any invalid {@code families} attribute value, including
+     * an empty list.
+     */
+    ImmutableSet<TargetDeviceFamily> families() {
+      List<String> rawFamilies = ruleContext.attributes().get(WATCH_EXT_FAMILIES_ATTR,
+          Type.STRING_LIST);
+      try {
+        return ImmutableSet.copyOf(TargetDeviceFamily.fromNamesInRule(rawFamilies));
+      } catch (InvalidFamilyNameException | RepeatedFamilyNameException e) {
+        return ImmutableSet.of();
+      }
+    }
+
+    @Nullable
+    Artifact provisioningProfile() {
+      Artifact explicitProvisioningProfile =
+          getPrerequisiteArtifact(WATCH_EXT_PROVISIONING_PROFILE_ATTR);
+      if (explicitProvisioningProfile != null) {
+        return explicitProvisioningProfile;
+      }
+      return getPrerequisiteArtifact(WATCH_EXT_DEFAULT_PROVISIONING_PROFILE_ATTR);
+    }
+
+    String bundleId() {
+      Preconditions.checkState(!Strings.isNullOrEmpty(
+          ruleContext.attributes().get(WATCH_EXT_BUNDLE_ID_ATTR, Type.STRING)),
+          "requires a bundle_id value");
+      return ruleContext.attributes().get(WATCH_EXT_BUNDLE_ID_ATTR, Type.STRING);
+    }
+
+    ImmutableList<Artifact> infoPlists() {
+      return getPrerequisiteArtifacts(WATCH_EXT_INFOPLISTS_ATTR);
+    }
+
+    ImmutableList<Artifact> strings() {
+      return getPrerequisiteArtifacts(WATCH_EXT_STRINGS_ATTR);
+    }
+
+    ImmutableList<Artifact> resources() {
+      return getPrerequisiteArtifacts(WATCH_EXT_RESOURCES_ATTR);
+    }
+
+    ImmutableList<Artifact> structuredResources() {
+      return getPrerequisiteArtifacts(WATCH_EXT_STRUCTURED_RESOURCES_ATTR);
+    }
+
+    @Nullable
+    Artifact entitlements() {
+      return getPrerequisiteArtifact(WATCH_EXT_ENTITLEMENTS_ATTR);
+    }
+
+    private boolean isBundleIdExplicitySpecified() {
+      return ruleContext.attributes().isAttributeValueExplicitlySpecified(WATCH_EXT_BUNDLE_ID_ATTR);
+    }
+
+    private ImmutableList<Artifact> getPrerequisiteArtifacts(String attribute) {
+      return ruleContext.getPrerequisiteArtifacts(attribute, Mode.TARGET).list();
+    }
+
+    @Nullable
+    private Artifact getPrerequisiteArtifact(String attribute) {
+      return ruleContext.getPrerequisiteArtifact(attribute, Mode.TARGET);
+    }
+  }
+
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/WatchUtils.java b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchUtils.java
new file mode 100644
index 0000000000..cc3492f997
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/WatchUtils.java
@@ -0,0 +1,172 @@
+// Copyright 2016 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.devtools.build.lib.rules.objc;
+
+import static com.google.devtools.build.lib.rules.objc.ObjcProvider.ROOT_MERGE_ZIP;
+
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Joiner;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Ordering;
+import com.google.devtools.build.lib.actions.Artifact;
+import com.google.devtools.build.lib.analysis.RuleContext;
+import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
+import com.google.devtools.build.lib.rules.apple.DottedVersion;
+import com.google.devtools.build.xcode.xcodegen.proto.XcodeGenProtos.XcodeprojBuildSetting;
+
+/**
+ * Contains support methods for common processing and generating of watch extension and
+ * application bundles.
+ */
+final class WatchUtils {
+
+  /**
+   * Supported Apple watch OS versions.
+   */
+  enum WatchOSVersion {
+    OS1(XcodeProductType.WATCH_OS1_APPLICATION, XcodeProductType.WATCH_OS1_EXTENSION,
+        "WatchKitSupport");
+
+    private final XcodeProductType applicationXcodeProductType;
+    private final XcodeProductType extensionXcodeProductType;
+    private final String watchKitSupportDirName;
+
+    WatchOSVersion(XcodeProductType applicationXcodeProductType,
+        XcodeProductType extensionXcodeProductType,
+        String watchKitSupportDirName) {
+      this.applicationXcodeProductType = applicationXcodeProductType;
+      this.extensionXcodeProductType = extensionXcodeProductType;
+      this.watchKitSupportDirName = watchKitSupportDirName;
+    }
+    
+    /**
+     * Returns the {@link XcodeProductType} to be used for the watch application's Xcode target.
+     */
+    XcodeProductType getApplicationXcodeProductType() {
+      return applicationXcodeProductType;
+    }
+
+    /**
+     * Returns the {@link XcodeProductType} to be used for the watch extension's Xcode target.
+     */
+    XcodeProductType getExtensionXcodeProductType() {
+      return extensionXcodeProductType;
+    }
+
+    /**
+     * Returns the name of the directory in the final iOS bundle which should contain the WatchKit
+     * support stub.
+     */
+    String getWatchKitSupportDirName() {
+      return watchKitSupportDirName;
+    }
+  }
+
+  @VisibleForTesting
+  static final String WATCH_KIT_STUB_PATH =
+      "${SDKROOT}/Library/Application\\ Support/WatchKit/WK";
+
+  // Apple only accepts watch extension and application starting at 8.2.
+  @VisibleForTesting
+  static final DottedVersion MINIMUM_OS_VERSION = DottedVersion.fromString("8.2");
+
+  /**
+   * Adds common xcode build settings required for watch bundles to the given xcode provider
+   * builder.
+   */
+  static void addXcodeSettings(RuleContext ruleContext,
+      XcodeProvider.Builder xcodeProviderBuilder) {
+    xcodeProviderBuilder.addMainTargetXcodeprojBuildSettings(xcodeSettings(ruleContext));
+  }
+
+  /**
+   * Watch Extension are not accepted by Apple below version 8.2. While applications built with a
+   * minimum iOS version of less than 8.2 may contain watch extension in their bundle, the
+   * extension itself needs to be built with 8.2 or higher. This logic overrides (if necessary)
+   * any flag-set minimum iOS version for extensions only so that this requirement is not
+   * violated.
+   */
+  static DottedVersion determineMinimumOsVersion(DottedVersion fromFlag) {
+    return Ordering.natural().max(fromFlag, MINIMUM_OS_VERSION);
+  }
+
+  static boolean isBuildingForWatchOS1Version(WatchOSVersion watchOSVersion) {
+    return watchOSVersion == WatchOSVersion.OS1;
+  }
+ 
+  /**
+   * Adds WatchKitSupport stub to the final ipa and exposes it to given @{link ObjcProvider.Builder}
+   * based on watch OS version.
+   *
+   * For example, for watch OS 1, the resulting ipa will have:
+   *   Payload/TestApp.app
+   *   WatchKitSupport
+   *   WatchKitSupport/WK
+   */
+  static void registerActionsToAddWatchSupport(
+      RuleContext ruleContext, ObjcProvider.Builder objcProviderBuilder,
+      WatchOSVersion watchOSVersion) {
+    Artifact watchSupportZip = watchSupportZip(ruleContext);
+    String workingDirectory = watchSupportZip.getExecPathString()
+        .substring(0, watchSupportZip.getExecPathString().lastIndexOf('/'));
+    String watchKitSupportDirName = watchOSVersion.getWatchKitSupportDirName();
+    String watchKitSupportPath = workingDirectory + "/" + watchKitSupportDirName;
+
+    ImmutableList<String> command = ImmutableList.of(
+        // 1. Copy WK stub binary to watchKitSupportPath.
+        "mkdir -p " + watchKitSupportPath,
+        "&&",
+        String.format("cp %s %s", WATCH_KIT_STUB_PATH, watchKitSupportPath),
+        // 2. cd to working directory.
+        "&&",
+        "cd " + workingDirectory,
+        // 3. Zip watchSupport.
+        "&&",
+        String.format(
+            "/usr/bin/zip -q -r -0 %s %s",
+            watchSupportZip.getFilename(),
+            watchKitSupportDirName));
+
+    ruleContext.registerAction(ObjcRuleClasses.spawnAppleEnvActionBuilder(ruleContext,
+        ruleContext.getFragment(AppleConfiguration.class).getBundlingPlatform())
+        .setProgressMessage("Copying Watchkit support to app bundle")
+        .setShellCommand(ImmutableList.of("/bin/bash", "-c", Joiner.on(" ").join(command)))
+        .addOutput(watchSupportZip)
+        .build(ruleContext));
+
+    objcProviderBuilder.add(ROOT_MERGE_ZIP, watchSupportZip(ruleContext));
+  }
+
+  private static Artifact watchSupportZip(RuleContext ruleContext) {
+    return ruleContext.getRelatedArtifact(
+        ruleContext.getUniqueDirectory("_watch"), "/WatchKitSupport.zip");
+  }
+
+  private static Iterable<XcodeprojBuildSetting> xcodeSettings(RuleContext ruleContext) {
+    ImmutableList.Builder<XcodeprojBuildSetting> xcodeSettings = new ImmutableList.Builder<>();
+    xcodeSettings.add(
+        XcodeprojBuildSetting.newBuilder()
+            .setName("RESOURCES_TARGETED_DEVICE_FAMILY")
+            .setValue(TargetDeviceFamily.WATCH.getNameInRule())
+            .build());
+    xcodeSettings.add(
+        XcodeprojBuildSetting.newBuilder()
+            .setName("IPHONEOS_DEPLOYMENT_TARGET")
+            .setValue(determineMinimumOsVersion(
+                ObjcRuleClasses.objcConfiguration(ruleContext).getMinimumOs()).toString())
+            .build());
+    return xcodeSettings.build();
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProductType.java b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProductType.java
index 61e87c0a7d..df912c3df3 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProductType.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProductType.java
@@ -24,7 +24,9 @@ enum XcodeProductType {
   APPLICATION("com.apple.product-type.application"),
   UNIT_TEST("com.apple.product-type.bundle.unit-test"),
   EXTENSION("com.apple.product-type.app-extension"),
-  FRAMEWORK("com.apple.product-type.framework");
+  FRAMEWORK("com.apple.product-type.framework"),
+  WATCH_OS1_APPLICATION("com.apple.product-type.application.watchapp"),
+  WATCH_OS1_EXTENSION("com.apple.product-type.watchkit-extension");
 
   private final String identifier;
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProvider.java b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProvider.java
index baae5551e1..45ba704c3e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeProvider.java
@@ -183,7 +183,8 @@ public final class XcodeProvider implements TransitiveInfoProvider {
         // TODO(bazel-team): This is messy. Maybe we should make XcodeProvider be able to specify
         // how to depend on it rather than require this method to choose based on the dependency's
         // type.
-        if (dependency.productType == XcodeProductType.EXTENSION) {
+        if (dependency.productType == XcodeProductType.EXTENSION
+            || dependency.productType == XcodeProductType.WATCH_OS1_EXTENSION) {
           this.extensions.add(dependency);
           this.inputsToXcodegen.addTransitive(dependency.inputsToXcodegen);
           this.additionalSources.addTransitive(dependency.additionalSources);
@@ -489,7 +490,8 @@ public final class XcodeProvider implements TransitiveInfoProvider {
   @VisibleForTesting
   static final EnumSet<XcodeProductType> CAN_LINK_PRODUCT_TYPES = EnumSet.of(
       XcodeProductType.APPLICATION, XcodeProductType.BUNDLE, XcodeProductType.UNIT_TEST,
-      XcodeProductType.EXTENSION, XcodeProductType.FRAMEWORK);
+      XcodeProductType.EXTENSION, XcodeProductType.FRAMEWORK, XcodeProductType.WATCH_OS1_EXTENSION,
+      XcodeProductType.WATCH_OS1_APPLICATION);
 
   /**
    * Returns the name of the Xcode target that corresponds to a build target with the given name.
@@ -606,11 +608,12 @@ public final class XcodeProvider implements TransitiveInfoProvider {
         // but do have a dummy source file to make Xcode happy.
         boolean hasSources = dependency.compilationArtifacts.isPresent()
             && dependency.compilationArtifacts.get().getArchive().isPresent();
-        if (hasSources || (dependency.productType == XcodeProductType.BUNDLE)) {
+        if (hasSources || (dependency.productType == XcodeProductType.BUNDLE
+            || (dependency.productType == XcodeProductType.WATCH_OS1_APPLICATION))) {
           String dependencyXcodeTargetName = dependency.dependencyXcodeTargetName();
           dependencySet.add(DependencyControl.newBuilder()
-                .setTargetLabel(dependencyXcodeTargetName)
-                .build());
+              .setTargetLabel(dependencyXcodeTargetName)
+              .build());
         }
       }
 
diff --git a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeSupport.java b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeSupport.java
index 4c1dcac8d8..e50f2da56e 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeSupport.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/objc/XcodeSupport.java
@@ -25,6 +25,7 @@ import com.google.devtools.build.lib.analysis.RuleContext;
 import com.google.devtools.build.lib.analysis.actions.BinaryFileWriteAction;
 import com.google.devtools.build.lib.analysis.actions.SpawnAction;
 import com.google.devtools.build.lib.analysis.actions.SymlinkAction;
+import com.google.devtools.build.lib.cmdline.Label;
 import com.google.devtools.build.lib.collect.nestedset.NestedSetBuilder;
 import com.google.devtools.build.lib.packages.ImplicitOutputsFunction.SafeImplicitOutputsFunction;
 import com.google.devtools.build.lib.rules.apple.AppleConfiguration;
@@ -56,12 +57,26 @@ public final class XcodeSupport {
       fromTemplates("%{name}.xcodeproj/project.pbxproj");
 
   private final RuleContext ruleContext;
+  private final IntermediateArtifacts intermediateArtifacts;
+  private final Label xcodeTargetLabel;
 
   /**
    * Creates a new xcode support for the given context.
    */
-  XcodeSupport(RuleContext ruleContext) {
+  XcodeSupport(RuleContext ruleContext)  {
+    this(ruleContext, ObjcRuleClasses.intermediateArtifacts(ruleContext), ruleContext.getLabel());
+  }
+
+  /**
+   * Creates a new xcode support for the given context and {@link IntermediateArtifacts} with given
+   * target label.
+   */
+  public XcodeSupport(
+      RuleContext ruleContext, IntermediateArtifacts intermediateArtifacts,
+      Label xcodeTargetLabel) {
     this.ruleContext = ruleContext;
+    this.intermediateArtifacts = intermediateArtifacts;
+    this.xcodeTargetLabel = xcodeTargetLabel;
   }
 
   /**
@@ -83,9 +98,6 @@ public final class XcodeSupport {
    * @return this xcode support
    */
   XcodeSupport addDummySource(XcodeProvider.Builder xcodeProviderBuilder) {
-    IntermediateArtifacts intermediateArtifacts =
-        ObjcRuleClasses.intermediateArtifacts(ruleContext);
-
     ruleContext.registerAction(new SymlinkAction(
         ruleContext.getActionOwner(),
         ruleContext.getPrerequisiteArtifact("$dummy_source", Mode.TARGET),
@@ -154,7 +166,7 @@ public final class XcodeSupport {
       ObjcProvider objcProvider, XcodeProductType productType, String architecture,
       ConfigurationDistinguisher configurationDistinguisher) {
     xcodeProviderBuilder
-        .setLabel(ruleContext.getLabel())
+        .setLabel(xcodeTargetLabel)
         .setArchitecture(architecture)
         .setConfigurationDistinguisher(configurationDistinguisher)
         .setObjcProvider(objcProvider)
@@ -210,8 +222,7 @@ public final class XcodeSupport {
   }
 
   private void registerXcodegenActions(XcodeProvider.Project project) throws InterruptedException {
-    Artifact controlFile =
-        ObjcRuleClasses.intermediateArtifacts(ruleContext).pbxprojControlArtifact();
+    Artifact controlFile = intermediateArtifacts.pbxprojControlArtifact();
 
     ruleContext.registerAction(new BinaryFileWriteAction(
         ruleContext.getActionOwner(),