--- a/testing/mochitest/mach_commands.py
+++ b/testing/mochitest/mach_commands.py
@@ -193,17 +193,17 @@ class MochitestRunner(MozbuildObject):
         return mochitest.run_remote_mochitests(parser, options)
 
     def run_desktop_test(self, suite=None, test_file=None, debugger=None,
         debugger_args=None, shuffle=False, keep_open=False, rerun_failures=False,
         no_autorun=False, repeat=0, run_until_failure=False, slow=False,
         chunk_by_dir=0, total_chunks=None, this_chunk=None, jsdebugger=False,
         debug_on_failure=False, start_at=None, end_at=None, e10s=False,
         dmd=False, dump_output_directory=None, dump_about_memory_after_test=False,
-        dump_dmd_after_test=False, install_extension=None):
+        dump_dmd_after_test=False, install_extension=None, **kwargs):
         """Runs a mochitest.
 
         test_file is a path to a test file. It can be a relative path from the
         top source directory, an absolute filename, or a directory containing
         test files.
 
         suite is the type of mochitest to run. It can be one of ('plain',
         'chrome', 'browser', 'metro', 'a11y').
@@ -310,16 +310,19 @@ class MochitestRunner(MozbuildObject):
         options.dumpDMDAfterTest = dump_dmd_after_test
         options.dumpOutputDirectory = dump_output_directory
         mozinfo.update({"e10s": e10s}) # for test manifest parsing.
 
         options.failureFile = failure_file_path
         if install_extension != None:
             options.extensionsToInstall = [os.path.join(self.topsrcdir,install_extension)]
 
+        for k, v in kwargs.iteritems():
+            setattr(options, k, v)
+
         if test_path:
             test_root = runner.getTestRoot(options)
             test_root_file = mozpack.path.join(self.mochitest_dir, test_root, test_path)
             if not os.path.exists(test_root_file):
                 print('Specified test path does not exist: %s' % test_root_file)
                 print('You may need to run |mach build| to build the test files.')
                 return 1