--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -1370,55 +1370,68 @@ toolbar#nav-bar {
                 exists=False, disabled=disabled, filters=filters, **info)
 
             if len(tests) == 0:
                 self.log.error("no tests to run using specified "
                                "combination of filters: {}".format(
                                    manifest.fmt_filters()))
 
         paths = []
+
+        # When running mochitest locally the manifest is based on topsrcdir,
+        # but when running in automation it is based on the test root.
+        manifest_root = build_obj.topsrcdir if build_obj else self.testRootAbs
+        manifests = set()
         for test in tests:
             if len(tests) == 1 and 'disabled' in test:
                 del test['disabled']
 
             pathAbs = os.path.abspath(test['path'])
             assert pathAbs.startswith(self.testRootAbs)
             tp = pathAbs[len(self.testRootAbs):].replace('\\', '/').strip('/')
 
             if not self.isTest(options, tp):
                 self.log.warning(
                     'Warning: %s from manifest %s is not a valid test' %
                     (test['name'], test['manifest']))
                 continue
 
+            manifests.add(os.path.relpath(test['manifest'], manifest_root))
+
             testob = {'path': tp}
             if 'disabled' in test:
                 testob['disabled'] = test['disabled']
             if 'expected' in test:
                 testob['expected'] = test['expected']
             if 'scheme' in test:
                 testob['scheme'] = test['scheme']
             paths.append(testob)
 
         def path_sort(ob1, ob2):
             path1 = ob1['path'].split('/')
             path2 = ob2['path'].split('/')
             return cmp(path1, path2)
 
         paths.sort(path_sort)
-        self._active_tests = paths
         if options.dump_tests:
             options.dump_tests = os.path.expanduser(options.dump_tests)
             assert os.path.exists(os.path.dirname(options.dump_tests))
             with open(options.dump_tests, 'w') as dumpFile:
-                dumpFile.write(json.dumps({'active_tests': self._active_tests}))
+                dumpFile.write(json.dumps({'active_tests': paths}))
 
             self.log.info("Dumping active_tests to %s file." % options.dump_tests)
             sys.exit()
 
+        # Upload a list of test manifests that were executed in this run.
+        if 'MOZ_UPLOAD_DIR' in os.environ:
+            artifact = os.path.join(os.environ['MOZ_UPLOAD_DIR'], 'manifests.list')
+            with open(artifact, 'a') as fh:
+                fh.write('\n'.join(sorted(manifests)))
+
+        self._active_tests = paths
         return self._active_tests
 
     def getTestManifest(self, options):
         if isinstance(options.manifestFile, TestManifest):
             manifest = options.manifestFile
         elif options.manifestFile and os.path.isfile(options.manifestFile):
             manifestFileAbs = os.path.abspath(options.manifestFile)
             assert manifestFileAbs.startswith(SCRIPT_DIR)