diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/installer/l10n-repack.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/installer/l10n-repack.py	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,48 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+'''
+Replace localized parts of a packaged directory with data from a langpack
+directory.
+'''
+
+from mozpack.packager import l10n
+from argparse import ArgumentParser
+import buildconfig
+
+# Set of files or directories not listed in a chrome.manifest but that are
+# localized.
+NON_CHROME = set([
+    '**/crashreporter*.ini',
+    'searchplugins',
+    'dictionaries',
+    'hyphenation',
+    'defaults/profile',
+    'defaults/pref*/*-l10n.js',
+    'update.locale',
+    'updater.ini',
+    'extensions/langpack-*@*',
+    'distribution/extensions/langpack-*@*',
+    'chrome/**/searchplugins/*.xml',
+])
+
+
+def main():
+    parser = ArgumentParser()
+    parser.add_argument('build',
+                        help='Directory containing the build to repack')
+    parser.add_argument('l10n',
+                        help='Directory containing the staged langpack')
+    parser.add_argument('--non-resource', nargs='+', metavar='PATTERN',
+                        default=[],
+                        help='Extra files not to be considered as resources')
+    args = parser.parse_args()
+
+    buildconfig.substs['USE_ELF_HACK'] = False
+    buildconfig.substs['PKG_SKIP_STRIP'] = True
+    l10n.repack(args.build, args.l10n, args.non_resource, NON_CHROME)
+
+
+if __name__ == "__main__":
+    main()