--- a/testing/marionette/mach_commands.py
+++ b/testing/marionette/mach_commands.py
@@ -14,31 +14,22 @@ from mozbuild.base import (
 )
 
 from mach.decorators import (
     CommandArgument,
     CommandProvider,
     Command,
 )
 
-MARIONETTE_DISABLED_B2G = '''
-The %s command requires a Marionette-enabled build.
-
-Please create an engineering build, which has Marionette enabled.  You can do
-this by ommitting the VARIANT variable when building, or using:
-
-VARIANT=eng ./build.sh
-'''
 
 def setup_argument_parser():
     from marionette.runner.base import BaseMarionetteArguments
     return BaseMarionetteArguments()
 
-def run_marionette(tests, b2g_path=None, emulator=None,
-    address=None, binary=None, topsrcdir=None, **kwargs):
+def run_marionette(tests, testtype=None, address=None, binary=None, topsrcdir=None, **kwargs):
     from mozlog.structured import commandline
 
     from marionette.runtests import (
         MarionetteTestRunner,
         BaseMarionetteArguments,
         MarionetteHarness
     )
 
@@ -46,23 +37,18 @@ def run_marionette(tests, b2g_path=None,
     commandline.add_logging_group(parser)
 
     if not tests:
         tests = [os.path.join(topsrcdir,
                  'testing/marionette/harness/marionette/tests/unit-tests.ini')]
 
     args = parser.parse_args(args=tests)
 
-    if b2g_path:
-        args.homedir = b2g_path
-        if emulator:
-            args.emulator = emulator
-    else:
-        args.binary = binary
-        path, exe = os.path.split(args.binary)
+    args.binary = binary
+    path, exe = os.path.split(args.binary)
 
     for k, v in kwargs.iteritems():
         setattr(args, k, v)
 
     parser.verify_usage(args)
 
     args.logger = commandline.setup_logging("Marionette Unit Tests",
                                             args,