new file mode 100644
--- /dev/null
+++ b/layout/tools/reftest/mach_test_package_commands.py
@@ -0,0 +1,53 @@
+# 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/.
+
+from __future__ import unicode_literals
+
+import os
+from functools import partial
+
+from mach.decorators import (
+    CommandProvider,
+    Command,
+)
+
+
+def run_reftest(context, **kwargs):
+    kwargs['certPath'] = context.certs_dir
+    kwargs['utilityPath'] = context.bin_dir
+    kwargs['extraProfileFiles'].append(os.path.join(context.bin_dir, 'plugins'))
+
+    if not kwargs['app']:
+        # This could still return None in which case --appname must be used
+        # to specify the firefox binary.
+        kwargs['app'] = context.find_firefox()
+
+    if not kwargs['tests']:
+        kwargs['tests'] = [os.path.join('layout', 'reftests', 'reftest.list')]
+
+    test_root = os.path.join(context.package_root, 'reftest', 'tests')
+    normalize = partial(context.normalize_test_path, test_root)
+    kwargs['tests'] = map(normalize, kwargs['tests'])
+
+    from runreftest import run as run_test_harness
+    return run_test_harness(**kwargs)
+
+
+def setup_argument_parser():
+    from reftestcommandline import DesktopArgumentsParser
+    return DesktopArgumentsParser()
+
+
+@CommandProvider
+class ReftestCommands(object):
+
+    def __init__(self, context):
+        self.context = context
+
+    @Command('reftest', category='testing',
+             description='Run the reftest harness.',
+             parser=setup_argument_parser)
+    def reftest(self, **kwargs):
+        kwargs['suite'] = 'reftest'
+        return run_reftest(self.context, **kwargs)

--- a/layout/tools/reftest/moz.build
+++ b/layout/tools/reftest/moz.build
@@ -17,16 +17,17 @@ GENERATED_FILES += ['automation.py']
 TEST_HARNESS_FILES.reftest += [
     '!automation.py',
     '/build/mobile/b2gautomation.py',
     '/build/mobile/remoteautomation.py',
     '/build/pgo/server-locations.txt',
     '/testing/mochitest/server.js',
     'b2g_start_script.js',
     'gaia_lock_screen.js',
+    'mach_test_package_commands.py',
     'output.py',
     'reftest-preferences.js',
     'reftestcommandline.py',
     'remotereftest.py',
     'runreftest.py',
     'runreftestb2g.py',
     'runreftestmulet.py',
 ]

--- a/layout/tools/reftest/reftestcommandline.py
+++ b/layout/tools/reftest/reftestcommandline.py
@@ -367,28 +367,16 @@ class DesktopArgumentsParser(ReftestArgu
         if options.app is None:
             bin_dir = (self.build_obj.get_binary_path() if
                        self.build_obj and self.build_obj.substs[
                            'MOZ_BUILD_APP'] != 'mobile/android'
                        else None)
 
             if bin_dir:
                 options.app = bin_dir
-            else:
-                self.error(
-                    "could not find the application path, --appname must be specified")
-
-        options.app = reftest.getFullPath(options.app)
-        if not os.path.exists(options.app):
-            self.error("""Error: Path %(app)s doesn't exist.
-            Are you executing $objdir/_tests/reftest/runreftest.py?"""
-                       % {"app": options.app})
-
-        if options.xrePath is None:
-            options.xrePath = os.path.dirname(options.app)
 
         if options.symbolsPath and len(urlparse(options.symbolsPath).scheme) < 2:
             options.symbolsPath = reftest.getFullPath(options.symbolsPath)
 
         options.utilityPath = reftest.getFullPath(options.utilityPath)
 
 
 class B2GArgumentParser(ReftestArgumentsParser):

--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -32,18 +32,21 @@ import mozprocess
 import mozprofile
 import mozrunner
 from mozrunner.utils import get_stack_fixer_function, test_environment
 from mozscreenshot import printstatus, dump_screen
 
 try:
     from marionette import Marionette
     from marionette_driver.addons import Addons
-except ImportError:
-    Marionette=None
+except ImportError, e:
+    # Defer ImportError until attempt to use Marionette
+    def reraise(*args, **kwargs):
+        raise(e)
+    Marionette = reraise
 
 from output import OutputHandler, ReftestFormatter
 import reftestcommandline
 
 here = os.path.abspath(os.path.dirname(__file__))
 
 try:
     from mozbuild.base import MozbuildObject
@@ -720,13 +723,27 @@ def run(**kwargs):
     if 'tests' in kwargs:
         options = parser.parse_args(kwargs["tests"])
     else:
         options = parser.parse_args()
 
     reftest = RefTest()
     parser.validate(options, reftest)
 
+    # We have to validate options.app here for the case when the mach
+    # command is able to find it after argument parsing. This can happen
+    # when running from a tests.zip.
+    if not options.app:
+        parser.error("could not find the application path, --appname must be specified")
+
+    options.app = reftest.getFullPath(options.app)
+    if not os.path.exists(options.app):
+        parser.error("Error: Path %(app)s doesn't exist. Are you executing "
+                     "$objdir/_tests/reftest/runreftest.py?" % {"app": options.app})
+
+    if options.xrePath is None:
+        options.xrePath = os.path.dirname(options.app)
+
     return reftest.runTests(options.tests, options)
 
 
 if __name__ == "__main__":
     sys.exit(run())

--- a/testing/tools/mach_test_package_bootstrap.py
+++ b/testing/tools/mach_test_package_bootstrap.py
@@ -29,24 +29,26 @@ SEARCH_PATHS = [
     'mozbase/moznetwork',
     'mozbase/mozprocess',
     'mozbase/mozprofile',
     'mozbase/mozrunner',
     'mozbase/mozscreenshot',
     'mozbase/mozsystemmonitor',
     'mozbase/moztest',
     'mozbase/mozversion',
+    'reftest',
     'tools/mach',
     'tools/wptserve',
     'xpcshell',
 ]
 
 # Individual files providing mach commands.
 MACH_MODULES = [
     'mochitest/mach_test_package_commands.py',
+    'reftest/mach_test_package_commands.py',
     'tools/mach/mach/commands/commandinfo.py',
     'xpcshell/mach_test_package_commands.py',
 ]
 
 
 CATEGORIES = {
     'testing': {
         'short': 'Testing',