diff --git a/layout/tools/reftest/runreftestb2g.py b/layout/tools/reftest/runreftestb2g.py
index 3f7be4beaccd..7afd72ad699b 100644
--- a/layout/tools/reftest/runreftestb2g.py
+++ b/layout/tools/reftest/runreftestb2g.py
@@ -505,14 +505,16 @@ def run_remote_reftests(parser, options, args):
     marionette = Marionette.getMarionetteOrExit(**kwargs)
     auto.marionette = marionette
 
-    # create the DeviceManager
-    kwargs = {'adbPath': options.adbPath,
-              'deviceRoot': options.remoteTestRoot}
-    if options.deviceIP:
-        kwargs.update({'host': options.deviceIP,
-                       'port': options.devicePort})
-
-    dm = DeviceManagerADB(**kwargs)
+    if options.emulator:
+        dm = marionette.emulator.dm
+    else:
+        # create the DeviceManager
+        kwargs = {'adbPath': options.adbPath,
+                  'deviceRoot': options.remoteTestRoot}
+        if options.deviceIP:
+            kwargs.update({'host': options.deviceIP,
+                           'port': options.devicePort})
+        dm = DeviagerADB(**kwargs)
     auto.setDeviceManager(dm)
 
     options = parser.verifyRemoteOptions(options)
diff --git a/testing/mochitest/runtestsb2g.py b/testing/mochitest/runtestsb2g.py
index 10b63a324df8..1cde4e6f1c40 100644
--- a/testing/mochitest/runtestsb2g.py
+++ b/testing/mochitest/runtestsb2g.py
@@ -310,13 +310,17 @@ def run_remote_mochitests(parser, options):
 
     marionette = Marionette.getMarionetteOrExit(**kwargs)
 
-    # create the DeviceManager
-    kwargs = {'adbPath': options.adbPath,
-              'deviceRoot': options.remoteTestRoot}
-    if options.deviceIP:
-        kwargs.update({'host': options.deviceIP,
-                       'port': options.devicePort})
-    dm = DeviceManagerADB(**kwargs)
+    if options.emulator:
+        dm = marionette.emulator.dm
+    else:
+        # create the DeviceManager
+        kwargs = {'adbPath': options.adbPath,
+                  'deviceRoot': options.remoteTestRoot}
+        if options.deviceIP:
+            kwargs.update({'host': options.deviceIP,
+                           'port': options.devicePort})
+        dm = DeviceManagerADB(**kwargs)
+
     options = parser.verifyRemoteOptions(options)
     if (options == None):
         print "ERROR: Invalid options specified, use --help for a list of valid options"
diff --git a/testing/xpcshell/runtestsb2g.py b/testing/xpcshell/runtestsb2g.py
index e2b7a447d00c..55e417b70b02 100644
--- a/testing/xpcshell/runtestsb2g.py
+++ b/testing/xpcshell/runtestsb2g.py
@@ -183,13 +183,16 @@ def main():
             kwargs['connectToRunningEmulator'] = True
     marionette = Marionette(**kwargs)
 
-    # Create the DeviceManager instance
-    kwargs = {'adbPath': options.adb_path}
-    if options.deviceIP:
-        kwargs['host'] = options.deviceIP
-        kwargs['port'] = options.devicePort
-    kwargs['deviceRoot'] = options.remoteTestRoot
-    dm = devicemanagerADB.DeviceManagerADB(**kwargs)
+    if options.emulator:
+        dm = marionette.emulator.dm
+    else:
+        # Create the DeviceManager instance
+        kwargs = {'adbPath': options.adb_path}
+        if options.deviceIP:
+            kwargs['host'] = options.deviceIP
+            kwargs['port'] = options.devicePort
+        kwargs['deviceRoot'] = options.remoteTestRoot
+        dm = devicemanagerADB.DeviceManagerADB(**kwargs)
 
     if not options.remoteTestRoot:
         options.remoteTestRoot = dm.getDeviceRoot()