new file mode 100644
--- /dev/null
+++ b/testing/mozharness/configs/taskcluster_nightly.py
@@ -0,0 +1,5 @@
+config = {
+    'nightly_build': True,
+    'taskcluster_nightly': True,
+}
+

--- a/testing/mozharness/mozharness/mozilla/building/buildbase.py
+++ b/testing/mozharness/mozharness/mozilla/building/buildbase.py
@@ -913,16 +913,24 @@ or run without that action (ie: --no-{ac
                     'stage_ssh_key': c['stage_ssh_key']
                 }
 
         if self.query_is_nightly():
             mach_env['LATEST_MAR_DIR'] = c['latest_mar_dir'] % {
                 'branch': self.branch
             }
 
+        # this prevents taskcluster from overwriting the target files with
+        # the multilocale files. Put everything from the en-US build in a
+        # separate folder.
+        if multiLocale and self.config.get('taskcluster_nightly'):
+            if 'UPLOAD_PATH' in mach_env:
+                mach_env['UPLOAD_PATH'] = os.path.join(mach_env['UPLOAD_PATH'],
+                                                       'en-US')
+
         # _query_post_upload_cmd returns a list (a cmd list), for env sake here
         # let's make it a string
         if c.get('is_automation'):
             pst_up_cmd = ' '.join([str(i) for i in self._query_post_upload_cmd(multiLocale)])
             mach_env['POST_UPLOAD_CMD'] = pst_up_cmd
 
         return mach_env
 
@@ -1630,27 +1638,38 @@ or run without that action (ie: --no-{ac
         if not self.query_is_nightly():
             self.info("Not a nightly build, skipping multi l10n.")
             return
         self._initialize_taskcluster()
 
         dirs = self.query_abs_dirs()
         base_work_dir = dirs['base_work_dir']
         objdir = dirs['abs_obj_dir']
-        branch = self.buildbot_config['properties']['branch']
+        branch = self.branch
 
         # Some android versions share the same .json config - if
         # multi_locale_config_platform is set, use that the .json name;
         # otherwise, use the buildbot platform.
+        default_platform = self.buildbot_config['properties'].get('platform',
+                                                                  'android')
+
         multi_config_pf = self.config.get('multi_locale_config_platform',
-                                          self.buildbot_config['properties']['platform'])
+                                          default_platform)
+
+        # The l10n script location differs on buildbot and taskcluster
+        if self.config.get('taskcluster_nightly'):
+            multil10n_path = \
+                'build/src/testing/mozharness/scripts/multil10n.py'
+            base_work_dir = os.path.join(base_work_dir, 'workspace')
+        else:
+            multil10n_path = '%s/scripts/scripts/multil10n.py' % base_work_dir,
 
         cmd = [
             self.query_exe('python'),
-            '%s/scripts/scripts/multil10n.py' % base_work_dir,
+            multil10n_path,
             '--config-file',
             'multi_locale/%s_%s.json' % (branch, multi_config_pf),
             '--config-file',
             'multi_locale/android-mozharness-build.json',
             '--merge-locales',
             '--pull-locale-source',
             '--add-locales',
             '--package-multi',