diff --git a/packages/metro-bundler/src/Bundler/Bundle.js b/packages/metro-bundler/src/Bundler/Bundle.js
index 3db9bf58..e9a58550 100644
--- a/packages/metro-bundler/src/Bundler/Bundle.js
+++ b/packages/metro-bundler/src/Bundler/Bundle.js
@@ -26,6 +26,8 @@ const {isMappingsMap} = require('../lib/SourceMap');
 import type {IndexMap, MappingsMap, SourceMap} from '../lib/SourceMap';
 import type {GetSourceOptions, FinalizeOptions} from './BundleBase';
 
+import type {PostProcessBundleSourcemap} from './index.js';
+
 export type Unbundle = {
   startupModules: Array<*>,
   lazyModules: Array<*>,
@@ -47,12 +49,14 @@ class Bundle extends BundleBase {
   _sourceMap: string | null;
   _sourceMapFormat: SourceMapFormat;
   _sourceMapUrl: ?string;
+  postProcessBundleSourcemap: ?PostProcessBundleSourcemap;
 
-  constructor({sourceMapUrl, dev, minify, ramGroups}: {
+  constructor({sourceMapUrl, dev, minify, ramGroups, postProcessBundleSourcemap}: {
     sourceMapUrl: ?string,
     dev?: boolean,
     minify?: boolean,
     ramGroups?: Array<string>,
+    postProcessBundleSourcemap?: PostProcessBundleSourcemap,
   } = {}) {
     super();
     this._sourceMap = null;
@@ -64,6 +68,7 @@ class Bundle extends BundleBase {
 
     this._ramGroups = ramGroups;
     this._ramBundle = null; // cached RAM Bundle
+    this.postProcessBundleSourcemap = postProcessBundleSourcemap;
   }
 
   addModule(
diff --git a/packages/metro-bundler/src/Bundler/index.js b/packages/metro-bundler/src/Bundler/index.js
index f0fc65af..efd0baaa 100644
--- a/packages/metro-bundler/src/Bundler/index.js
+++ b/packages/metro-bundler/src/Bundler/index.js
@@ -112,6 +112,12 @@ export type PostMinifyProcess = ({
   map: MappingsMap,
 }) => {code: string, map: MappingsMap};
 
+export type PostProcessBundleSourcemap = ({
+  code: string,
+  map: string,
+  outFileName: string,
+}) => {code: string, map: string};
+
 type Options = {|
   +allowBundleUpdates: boolean,
   +assetExts: Array<string>,
@@ -126,6 +132,7 @@ type Options = {|
   +platforms: Array<string>,
   +polyfillModuleNames: Array<string>,
   +postMinifyProcess: PostMinifyProcess,
+  +postProcessBundleSourcemap?: PostProcessBundleSourcemap,
   +postProcessModules?: PostProcessModules,
   +projectRoots: $ReadOnlyArray<string>,
   +providesModuleNodeModules?: Array<string>,
@@ -251,11 +258,17 @@ class Bundler {
     sourceMapUrl: ?string,
   }): Promise<Bundle> {
     const {dev, minify, unbundle} = options;
+    const postProcessBundleSourcemap = this._opts.postProcessBundleSourcemap;
     return this._resolverPromise.then(
       resolver => resolver.getModuleSystemDependencies({dev, unbundle}),
     ).then(moduleSystemDeps => this._bundle({
       ...options,
-      bundle: new Bundle({dev, minify, sourceMapUrl: options.sourceMapUrl}),
+      bundle: new Bundle({
+        dev,
+        minify,
+        sourceMapUrl: options.sourceMapUrl,
+        postProcessBundleSourcemap,
+      }),
       moduleSystemDeps,
     }));
   }
diff --git a/packages/metro-bundler/src/Server/index.js b/packages/metro-bundler/src/Server/index.js
index e5263769..18948dc5 100644
--- a/packages/metro-bundler/src/Server/index.js
+++ b/packages/metro-bundler/src/Server/index.js
@@ -37,6 +37,7 @@ import type {
   GetTransformOptions,
   PostProcessModules,
   PostMinifyProcess,
+  PostProcessBundleSourcemap,
 } from '../Bundler';
 import type {TransformCache} from '../lib/TransformCaching';
 import type {GlobalTransformCache} from '../lib/GlobalTransformCache';
@@ -76,6 +77,7 @@ type Options = {
   polyfillModuleNames?: Array<string>,
   postProcessModules?: PostProcessModules,
   postMinifyProcess: PostMinifyProcess,
+  postProcessBundleSourcemap: PostProcessBundleSourcemap,
   projectRoots: $ReadOnlyArray<string>,
   providesModuleNodeModules?: Array<string>,
   reporter: Reporter,
@@ -134,6 +136,7 @@ class Server {
     polyfillModuleNames: Array<string>,
     postProcessModules?: PostProcessModules,
     postMinifyProcess: PostMinifyProcess,
+    postProcessBundleSourcemap: PostProcessBundleSourcemap,
     projectRoots: $ReadOnlyArray<string>,
     providesModuleNodeModules?: Array<string>,
     reporter: Reporter,
@@ -180,6 +183,7 @@ class Server {
       polyfillModuleNames: options.polyfillModuleNames || [],
       postProcessModules: options.postProcessModules,
       postMinifyProcess: options.postMinifyProcess,
+      postProcessBundleSourcemap: options.postProcessBundleSourcemap,
       projectRoots: options.projectRoots,
       providesModuleNodeModules: options.providesModuleNodeModules,
       reporter: options.reporter,
diff --git a/packages/metro-bundler/src/index.js b/packages/metro-bundler/src/index.js
index bf189aa6..bced6330 100644
--- a/packages/metro-bundler/src/index.js
+++ b/packages/metro-bundler/src/index.js
@@ -20,7 +20,7 @@ const invariant = require('fbjs/lib/invariant');
 
 const {fromRawMappings, compactMapping} = require('./Bundler/source-map');
 
-import type {PostProcessModules, PostMinifyProcess} from './Bundler';
+import type {PostProcessModules, PostMinifyProcess, PostProcessBundleSourcemap} from './Bundler';
 import type Server from './Server';
 import type {GlobalTransformCache} from './lib/GlobalTransformCache';
 import type {TransformCache} from './lib/TransformCaching';
@@ -41,6 +41,7 @@ type Options = {
   +maxWorkers?: number,
   nonPersistent?: boolean,
   postMinifyProcess?: PostMinifyProcess,
+  postProcessBundleSourcemap?: PostProcessBundleSourcemap,
   postProcessModules?: PostProcessModules,
   projectRoots: $ReadOnlyArray<string>,
   reporter?: Reporter,
diff --git a/packages/metro-bundler/src/shared/output/bundle.js b/packages/metro-bundler/src/shared/output/bundle.js
index bf5eb73e..81ac4c1b 100644
--- a/packages/metro-bundler/src/shared/output/bundle.js
+++ b/packages/metro-bundler/src/shared/output/bundle.js
@@ -54,7 +54,10 @@ function saveBundleAndMap(
   } = options;
 
   log('start');
-  const codeWithMap = createCodeWithMap(bundle, !!dev, sourcemapSourcesRoot);
+  const origCodeWithMap = createCodeWithMap(bundle, !!dev, sourcemapSourcesRoot);
+  const codeWithMap = bundle.postProcessBundleSourcemap ?
+    bundle.postProcessBundleSourcemap({...origCodeWithMap, outFileName: bundleOutput}) :
+    origCodeWithMap;
   log('finish');
 
   log('Writing bundle output to:', bundleOutput);
diff --git a/yarn.lock b/yarn.lock
index f8e28fcd..f87a15a4 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -206,7 +206,7 @@ babel-code-frame@6.22.0, babel-code-frame@^6.16.0, babel-code-frame@^6.22.0:
     esutils "^2.0.2"
     js-tokens "^3.0.0"
 
-babel-core@^6.0.0, babel-core@^6.23.1, babel-core@^6.24.1:
+babel-core@^6.0.0, babel-core@^6.23.1, babel-core@^6.24.1, babel-core@^6.8.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-core/-/babel-core-6.24.1.tgz#8c428564dce1e1f41fb337ec34f4c3b022b5ad83"
   dependencies:
@@ -239,7 +239,7 @@ babel-eslint@^7.1.1:
     babel-types "^6.23.0"
     babylon "^6.17.0"
 
-babel-generator@^6.18.0, babel-generator@^6.24.1:
+babel-generator@^6.18.0, babel-generator@^6.24.1, babel-generator@^6.8.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-generator/-/babel-generator-6.24.1.tgz#e715f486c58ded25649d888944d52aa07c5d9497"
   dependencies:
@@ -668,7 +668,7 @@ babel-runtime@^6.22.0:
     core-js "^2.4.0"
     regenerator-runtime "^0.10.0"
 
-babel-template@^6.16.0, babel-template@^6.24.1:
+babel-template@^6.16.0, babel-template@^6.24.1, babel-template@^6.9.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-template/-/babel-template-6.24.1.tgz#04ae514f1f93b3a2537f2a0f60a5a45fb8308333"
   dependencies:
@@ -678,7 +678,7 @@ babel-template@^6.16.0, babel-template@^6.24.1:
     babylon "^6.11.0"
     lodash "^4.2.0"
 
-babel-traverse@^6.18.0, babel-traverse@^6.23.1, babel-traverse@^6.24.1:
+babel-traverse@^6.18.0, babel-traverse@^6.23.1, babel-traverse@^6.24.1, babel-traverse@^6.9.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-traverse/-/babel-traverse-6.24.1.tgz#ab36673fd356f9a0948659e7b338d5feadb31695"
   dependencies:
@@ -692,7 +692,7 @@ babel-traverse@^6.18.0, babel-traverse@^6.23.1, babel-traverse@^6.24.1:
     invariant "^2.2.0"
     lodash "^4.2.0"
 
-babel-types@^6.18.0, babel-types@^6.23.0, babel-types@^6.24.1:
+babel-types@^6.18.0, babel-types@^6.23.0, babel-types@^6.24.1, babel-types@^6.9.0:
   version "6.24.1"
   resolved "https://registry.yarnpkg.com/babel-types/-/babel-types-6.24.1.tgz#a136879dc15b3606bda0d90c1fc74304c2ff0975"
   dependencies:
@@ -705,7 +705,7 @@ babylon@7.0.0-beta.8:
   version "7.0.0-beta.8"
   resolved "https://registry.yarnpkg.com/babylon/-/babylon-7.0.0-beta.8.tgz#2bdc5ae366041442c27e068cce6f0d7c06ea9949"
 
-babylon@^6.11.0, babylon@^6.13.0, babylon@^6.15.0, babylon@^6.17.0:
+babylon@^6.11.0, babylon@^6.13.0, babylon@^6.15.0, babylon@^6.17.0, babylon@^6.5.2:
   version "6.17.1"
   resolved "https://registry.yarnpkg.com/babylon/-/babylon-6.17.1.tgz#17f14fddf361b695981fe679385e4f1c01ebd86f"
 
@@ -713,6 +713,10 @@ balanced-match@^0.4.1:
   version "0.4.2"
   resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-0.4.2.tgz#cb3f3e3c732dc0f01ee70b403f302e61d7709838"
 
+base62@^1.1.2:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/base62/-/base62-1.2.0.tgz#31e7e560dc846c9f44c1a531df6514da35474157"
+
 bcrypt-pbkdf@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/bcrypt-pbkdf/-/bcrypt-pbkdf-1.0.1.tgz#63bc5dcb61331b92bc05fd528953c33462a06f8d"
@@ -3055,6 +3059,20 @@ prelude-ls@~1.1.2:
   version "1.1.2"
   resolved "https://registry.yarnpkg.com/prelude-ls/-/prelude-ls-1.1.2.tgz#21932a549f5e52ffd9a827f570e04be62a97da54"
 
+prepack@^0.2.4:
+  version "0.2.4"
+  resolved "https://registry.yarnpkg.com/prepack/-/prepack-0.2.4.tgz#6b541b086cf7d67577dbc0bc2e941bdc14d989ca"
+  dependencies:
+    babel-core "^6.8.0"
+    babel-generator "^6.8.0"
+    babel-template "^6.9.0"
+    babel-traverse "^6.9.0"
+    babel-types "^6.9.0"
+    babylon "^6.5.2"
+    base62 "^1.1.2"
+    seedrandom "^2.4.2"
+    source-map "^0.5.6"
+
 preserve@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/preserve/-/preserve-0.2.0.tgz#815ed1f6ebc65926f865b310c0713bcb3315ce4b"
@@ -3373,6 +3391,10 @@ sax@^1.2.1:
   version "1.2.2"
   resolved "https://registry.yarnpkg.com/sax/-/sax-1.2.2.tgz#fd8631a23bc7826bef5d871bdb87378c95647828"
 
+seedrandom@^2.4.2:
+  version "2.4.3"
+  resolved "https://registry.yarnpkg.com/seedrandom/-/seedrandom-2.4.3.tgz#2438504dad33917314bff18ac4d794f16d6aaecc"
+
 "semver@2 || 3 || 4 || 5", semver@5.x, semver@^5.0.1, semver@^5.1.0, semver@^5.3.0:
   version "5.3.0"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.3.0.tgz#9b2ce5d3de02d17c6012ad326aa6b4d0cf54f94f"