--- a/testing/awsy/conf/base-prefs.json
+++ b/testing/awsy/conf/base-prefs.json
@@ -5,10 +5,11 @@
     "network.proxy.socks": "localhost",
     "network.proxy.socks_port": 90000,
     "network.proxy.socks_remote_dns": true,
     "network.proxy.type": 1,
     "plugin.disable": true,
     "startup.homepage_override_url": "",
     "startup.homepage_welcome_url": "",
     "browser.startup.homepage": "about:blank",
-    "browser.newtabpage.enabled": false
+    "browser.newtabpage.enabled": false,
+    "security.sandbox.content.level": 0
 }

--- a/testing/awsy/conf/prefs.json
+++ b/testing/awsy/conf/prefs.json
@@ -3,10 +3,11 @@
     "javascript.options.asyncstack": false,
     "image.mem.surfacecache.min_expiration_ms": 10000,
     "network.proxy.socks": "localhost",
     "network.proxy.socks_port": 90000,
     "network.proxy.socks_remote_dns": true,
     "network.proxy.type": 1,
     "plugin.disable": true,
     "startup.homepage_override_url": "",
-    "startup.homepage_welcome_url": ""
+    "startup.homepage_welcome_url": "",
+    "security.sandbox.content.level": 0
 }

--- a/testing/awsy/mach_commands.py
+++ b/testing/awsy/mach_commands.py
@@ -152,16 +152,22 @@ class MachCommands(MachCommandBase):
             if 'DMD' not in os.environ:
                 os.environ['DMD'] = '1'
 
             # Work around a startup crash with DMD on windows
             if mozinfo.os == 'win':
                 kwargs['pref'] = 'security.sandbox.content.level:0'
                 self.log(logging.WARNING, 'awsy', {},
                     'Forcing \'security.sandbox.content.level\' = 0 because DMD is enabled.')
+            elif mozinfo.os == 'mac':
+                # On mac binary is in MacOS and dmd.py is in Resources, ie:
+                #   Name.app/Contents/MacOS/libdmd.dylib
+                #   Name.app/Contents/Resources/dmd.py
+                bin_dir = os.path.join(bin_dir, "../Resources/")
+
 
             # Also add the bin dir to the python path so we can use dmd.py
             if bin_dir not in sys.path:
                 sys.path.append(bin_dir)
 
         for k, v in kwargs.iteritems():
             setattr(args, k, v)
 

--- a/testing/mozharness/scripts/awsy_script.py
+++ b/testing/mozharness/scripts/awsy_script.py
@@ -12,16 +12,18 @@ import copy
 import json
 import os
 import re
 import sys
 
 # load modules from parent dir
 sys.path.insert(1, os.path.dirname(sys.path[0]))
 
+import mozinfo
+
 from mozharness.base.script import PreScriptAction
 from mozharness.base.log import INFO, ERROR
 from mozharness.mozilla.testing.testbase import TestingMixin, testing_config_options
 from mozharness.base.vcs.vcsbase import MercurialScript
 from mozharness.mozilla.tooltool import TooltoolMixin
 from mozharness.mozilla.structuredlog import StructuredOutputParser
 from mozharness.mozilla.testing.codecoverage import (
     CodeCoverageMixin,
@@ -144,16 +146,39 @@ class AWSY(TestingMixin, MercurialScript
         '''
         dirs = self.abs_dirs
         env = {}
         error_summary_file = os.path.join(dirs['abs_blob_upload_dir'],
                                           'marionette_errorsummary.log')
 
         runtime_testvars = {'webRootDir': self.webroot_dir,
                             'resultsDir': self.results_dir}
+
+        # Check if this is a DMD build and if so enable it.
+        dmd_py_lib_dir = os.path.dirname(self.binary_path)
+        if mozinfo.os == 'mac':
+            # On mac binary is in MacOS and dmd.py is in Resources, ie:
+            #   Name.app/Contents/MacOS/libdmd.dylib
+            #   Name.app/Contents/Resources/dmd.py
+            dmd_py_lib_dir = os.path.join(dmd_py_lib_dir, "../Resources/")
+
+        dmd_path = os.path.join(dmd_py_lib_dir, "dmd.py")
+        if os.path.isfile(dmd_path):
+            runtime_testvars['dmd'] = True
+
+            # Allow the child process to import dmd.py
+            python_path = os.environ.get('PYTHONPATH')
+
+            if python_path:
+                os.environ['PYTHONPATH'] = "%s%s%s" % (python_path, os.pathsep, dmd_py_lib_dir)
+            else:
+                os.environ['PYTHONPATH'] = dmd_py_lib_dir
+
+            env['DMD']= "--mode=dark-matter --stacks=full"
+
         runtime_testvars_path = os.path.join(self.awsy_path, 'runtime-testvars.json')
         runtime_testvars_file = open(runtime_testvars_path, 'wb')
         runtime_testvars_file.write(json.dumps(runtime_testvars, indent=2))
         runtime_testvars_file.close()
 
         cmd = ['marionette']
 
         if self.config['test_about_blank']: