--- a/layout/tools/reftest/reftestcommandline.py
+++ b/layout/tools/reftest/reftestcommandline.py
@@ -139,16 +139,20 @@ class ReftestArgumentsParser(argparse.Ar
         self.add_argument("--marionette-port-timeout",
                           default=None,
                           help=argparse.SUPPRESS)
 
         self.add_argument("--marionette-socket-timeout",
                           default=None,
                           help=argparse.SUPPRESS)
 
+        self.add_argument("--marionette-startup-timeout",
+                          default=None,
+                          help=argparse.SUPPRESS)
+
         self.add_argument("--setenv",
                           action="append",
                           type=str,
                           default=[],
                           dest="environment",
                           metavar="NAME=VALUE",
                           help="sets the given variable in the application's "
                           "environment")

--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -614,16 +614,17 @@ class RefTest(object):
         runner.start(debug_args=debug_args,
                      interactive=interactive,
                      outputTimeout=timeout)
         proc = runner.process_handler
 
         if self.use_marionette:
             marionette_args = {
                 'socket_timeout': options.marionette_socket_timeout,
+                'startup_timeout': options.marionette_startup_timeout,
                 'symbols_path': options.symbolsPath,
             }
             if options.marionette:
                 host, port = options.marionette.split(':')
                 marionette_args['host'] = host
                 marionette_args['port'] = int(port)
 
             marionette = Marionette(**marionette_args)

--- a/testing/marionette/client/marionette_driver/marionette.py
+++ b/testing/marionette/client/marionette_driver/marionette.py
@@ -594,26 +594,26 @@ class Marionette(object):
         self.profile = None
         self.window = None
         self.chrome_window = None
         self.baseurl = baseurl
         self._test_name = None
         self.socket_timeout = socket_timeout
         self.crashed = 0
 
-        startup_timeout = startup_timeout or self.DEFAULT_STARTUP_TIMEOUT
+        self.startup_timeout = int(startup_timeout or self.DEFAULT_STARTUP_TIMEOUT)
         if self.bin:
             if not Marionette.is_port_available(self.port, host=self.host):
                 ex_msg = "{0}:{1} is unavailable.".format(self.host, self.port)
                 raise errors.MarionetteException(message=ex_msg)
 
             self.instance = GeckoInstance.create(
                 app, host=self.host, port=self.port, bin=self.bin, **instance_args)
             self.instance.start()
-            self.raise_for_port(timeout=startup_timeout)
+            self.raise_for_port(timeout=self.startup_timeout)
 
         self.timeout = Timeouts(self)
 
     @property
     def profile_path(self):
         if self.instance and self.instance.profile:
             return self.instance.profile.profile
 
@@ -1309,16 +1309,17 @@ class Marionette(object):
 
         self.client = transport.TcpTransport(
             self.host,
             self.port,
             self.socket_timeout)
 
         # Call wait_for_port() before attempting to connect in
         # the event gecko hasn't started yet.
+        timeout = timeout or self.startup_timeout
         self.wait_for_port(timeout=timeout)
         self.protocol, _ = self.client.connect()
 
         body = {"capabilities": capabilities, "sessionId": session_id}
         resp = self._send_message("newSession", body)
 
         self.session_id = resp["sessionId"]
         self.session = resp["value"] if self.protocol == 1 else resp["capabilities"]

--- a/testing/mochitest/mochitest_options.py
+++ b/testing/mochitest/mochitest_options.py
@@ -578,16 +578,21 @@ class MochitestArguments(ArgumentContain
           "help": "Timeout while waiting for the marionette port to open.",
           "suppress": True,
           }],
         [["--marionette-socket-timeout"],
          {"default": None,
           "help": "Timeout while waiting to receive a message from the marionette server.",
           "suppress": True,
           }],
+        [["--marionette-startup-timeout"],
+         {"default": None,
+          "help": "Timeout while waiting for marionette server startup.",
+          "suppress": True,
+          }],
         [["--cleanup-crashes"],
          {"action": "store_true",
           "dest": "cleanupCrashes",
           "default": False,
           "help": "Delete pending crash reports before running tests.",
           "suppress": True,
           }],
         [["--websocket-process-bridge-port"],

--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -2444,16 +2444,17 @@ toolbar#nav-bar {
                 detectShutdownLeaks = mozinfo.info[
                     "debug"] and options.flavor == 'browser'
 
             self.start_script_kwargs['flavor'] = self.normflavor(options.flavor)
             marionette_args = {
                 'symbols_path': options.symbolsPath,
                 'socket_timeout': options.marionette_socket_timeout,
                 'port_timeout': options.marionette_port_timeout,
+                'startup_timeout': options.marionette_startup_timeout,
             }
 
             if options.marionette:
                 host, port = options.marionette.split(':')
                 marionette_args['host'] = host
                 marionette_args['port'] = int(port)
 
             # testsToFilter parameter is used to filter out the test list that

--- a/testing/mozharness/configs/unittests/linux_unittest.py
+++ b/testing/mozharness/configs/unittests/linux_unittest.py
@@ -111,16 +111,17 @@ config = {
                 "--certificate-path=tests/certs",
                 "--setpref=webgl.force-enabled=true",
                 "--quiet",
                 "--log-raw=%(raw_log_file)s",
                 "--log-errorsummary=%(error_summary_file)s",
                 "--use-test-media-devices",
                 "--screenshot-on-fail",
                 "--cleanup-crashes",
+                "--marionette-startup-timeout=180",
             ],
             "run_filename": "runtests.py",
             "testsdir": "mochitest"
         },
         "mozbase": {
             "options": [
                 "-b",
                 "%(binary_path)s"