diff --git a/local-cli/bundle/output/bundle.js b/local-cli/bundle/output/bundle.js
index e4247982f5..2cbb7be08e 100644
--- a/local-cli/bundle/output/bundle.js
+++ b/local-cli/bundle/output/bundle.js
@@ -9,7 +9,7 @@
 'use strict';
 
 const Promise = require('promise');
-const sign = require('../sign');
+const hash = require('./hash');
 const writeFile = require('./writeFile');
 
 function buildBundle(packagerClient, requestOptions) {
@@ -36,7 +36,9 @@ function saveBundleAndMap(bundle, options, log) {
   log('finish');
 
   log('Writing bundle output to:', bundleOutput);
-  const writeBundle = writeFile(bundleOutput, sign(codeWithMap.code), encoding);
+
+  const code = hash.appendToString(codeWithMap.code, encoding);
+  const writeBundle = writeFile(bundleOutput, code, encoding);
   writeBundle.then(() => log('Done writing bundle output'));
 
   if (sourcemapOutput) {
diff --git a/local-cli/bundle/output/hash.js b/local-cli/bundle/output/hash.js
new file mode 100644
index 0000000000..c02c957461
--- /dev/null
+++ b/local-cli/bundle/output/hash.js
@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+'use strict';
+
+const crypto = require('crypto');
+
+const createHash = () => crypto.createHash('sha1');
+const isUTF8 = encoding => /^utf-?8$/i.test(encoding);
+
+exports.appendToString = (string, encoding) => {
+  const hash = createHash();
+  hash.update(string, encoding);
+  encoding = tryAsciiPromotion(string, encoding);
+  return string + formatSignature(encoding, hash);
+};
+
+function tryAsciiPromotion(string, encoding) {
+  if (!isUTF8(encoding)) { return encoding; }
+  for (let i = 0, n = string.length; i < n; i++) {
+    if (string.charCodeAt(i) > 0x7f) { return encoding; }
+  }
+  return 'ascii';
+}
+
+function formatSignature(encoding, hash) {
+  return `/*${encoding}:${hash.digest('hex')}*/`;
+}