diff --git a/mozilla/xpcom/threads/plevent.c b/mozilla/xpcom/threads/plevent.c
index a428af3d4ef..5b9b166af8f 100644
--- a/mozilla/xpcom/threads/plevent.c
+++ b/mozilla/xpcom/threads/plevent.c
@@ -71,7 +71,7 @@
 #if defined(XP_MAC) || defined(XP_MACOSX)
 #if defined(MOZ_WIDGET_COCOA)
 #include <CoreFoundation/CoreFoundation.h>
-#define MAC_USE_CFRUNLOOPSOURCE
+#define MAC_USE_CFMESSAGEPORT
 #elif defined(TARGET_CARBON)
 #include <CarbonEvents.h>
 #define MAC_USE_CARBON_EVENT
@@ -172,9 +172,10 @@ struct PLEventQueue {
 #elif defined(XP_BEOS)
     port_id             eventport;
 #elif defined(XP_MAC) || defined(XP_MACOSX)
-#if defined(MAC_USE_CFRUNLOOPSOURCE)
+#if defined(MAC_USE_CFMESSAGEPORT)
+    CFMessagePortRef    mLocalMessagePort;
+    CFMessagePortRef    mRemoteMessagePort;
     CFRunLoopSourceRef  mRunLoopSource;
-    CFRunLoopRef        mMainRunLoop;
 #elif defined(MAC_USE_CARBON_EVENT)
     EventHandlerUPP     eventHandlerUPP;
     EventHandlerRef     eventHandlerRef;
@@ -990,11 +991,14 @@ _pl_CleanupNativeNotifier(PLEventQueue* self)
 
 #elif defined(XP_OS2)
     WinDestroyWindow(self->eventReceiverWindow);
-#elif defined(MAC_USE_CFRUNLOOPSOURCE)
+#elif defined(MAC_USE_CFMESSAGEPORT)
 
-    CFRunLoopRemoveSource(self->mMainRunLoop, self->mRunLoopSource, kCFRunLoopCommonModes);
+    // XXX this assumes that the event queue is on the same run loop that it was created on
+    CFRunLoopRemoveSource(CFRunLoopGetCurrent(), self->mRunLoopSource, kCFRunLoopCommonModes);
     CFRelease(self->mRunLoopSource);
-    CFRelease(self->mMainRunLoop);
+
+    CFRelease(self->mRemoteMessagePort);
+    CFRelease(self->mLocalMessagePort);
 
 #elif defined(MAC_USE_CARBON_EVENT)
     EventComparatorUPP comparator = NewEventComparatorUPP(_md_CarbonEventComparator);
@@ -1298,9 +1302,18 @@ _pl_NativeNotify(PLEventQueue* self)
 static PRStatus
 _pl_NativeNotify(PLEventQueue* self)
 {
-#if defined(MAC_USE_CFRUNLOOPSOURCE)
-  	CFRunLoopSourceSignal(self->mRunLoopSource);
-  	CFRunLoopWakeUp(self->mMainRunLoop);
+#if defined(MAC_USE_CFMESSAGEPORT)
+    // send a request with no data (just to wake the receiver)
+    SInt32 err = CFMessagePortSendRequest(self->mRemoteMessagePort,
+                          0,      // msgid (arbitrary value; unused)
+                          NULL,   // data (none)
+                          1.0,    // sendTimeout (1 second)
+                          0.0,    // rcvTimeout
+                          NULL,   // replyMode (no reply expected)
+                          NULL    // returnData (none)
+              					);
+    PR_ASSERT(err == kCFMessagePortSuccess);
+
 #elif defined(MAC_USE_CARBON_EVENT)
     OSErr err;
     EventRef newEvent;
@@ -1615,11 +1628,12 @@ static void _md_CreateEventQueue( PLEventQueue *eventQueue )
 } /* end _md_CreateEventQueue() */
 #endif /* (defined(XP_UNIX) && !defined(XP_MACOSX)) || defined(XP_BEOS) */
 
-#if defined(MAC_USE_CFRUNLOOPSOURCE)
-static void _md_EventReceiverProc(void *info)
+#if defined(MAC_USE_CFMESSAGEPORT)
+static CFDataRef _md_EventReceiverProc(CFMessagePortRef local, SInt32 msgid, CFDataRef data, void *info)
 {
   PLEventQueue *queue = (PLEventQueue*)info;
   PL_ProcessPendingEvents(queue);
+  return NULL;
 }
 
 #elif defined(MAC_USE_CARBON_EVENT)
@@ -1667,21 +1681,35 @@ static pascal Boolean _md_CarbonEventComparator(EventRef inEvent,
 #if defined(XP_MAC) || defined(XP_MACOSX)
 static void _md_CreateEventQueue( PLEventQueue *eventQueue )
 {
-#if defined(MAC_USE_CFRUNLOOPSOURCE)
-    CFRunLoopSourceContext sourceContext = {0};
-    sourceContext.version = 0;
-    sourceContext.info = (void*)eventQueue;
-    sourceContext.perform = _md_EventReceiverProc;
+#if defined(MAC_USE_CFMESSAGEPORT)
+    CFMessagePortContext portContext = {
+      0,
+      (void*)eventQueue,
+      NULL, NULL, NULL
+    };
+
+    // create the local port (the receiver). Note that message ports are machine-wide,
+    // so we include the pid and event queue pointer in the name.
+    CFStringRef portName = CFStringCreateWithFormat(kCFAllocatorDefault, NULL,
+                              CFSTR("plevents_%d_%p"), getpid(), eventQueue);
+    eventQueue->mLocalMessagePort = CFMessagePortCreateLocal(kCFAllocatorDefault, portName,
+                              _md_EventReceiverProc, &portContext, NULL);
+
+    PR_ASSERT(eventQueue->mLocalMessagePort);
+    
+    // now create the remote port (the sender)
+    eventQueue->mRemoteMessagePort = CFMessagePortCreateRemote(kCFAllocatorDefault, portName);
+    PR_ASSERT(eventQueue->mRemoteMessagePort);
+
+    CFRelease(portName);
 
     // make a run loop source
-    eventQueue->mRunLoopSource = CFRunLoopSourceCreate(kCFAllocatorDefault, 0 /* order */, &sourceContext);
+    eventQueue->mRunLoopSource = CFMessagePortCreateRunLoopSource(kCFAllocatorDefault,
+                                      eventQueue->mLocalMessagePort, 0 /* order: ignored */);
     PR_ASSERT(eventQueue->mRunLoopSource);
     
-    eventQueue->mMainRunLoop = CFRunLoopGetCurrent();
-    CFRetain(eventQueue->mMainRunLoop);
-    
     // and add it to the run loop.
-    CFRunLoopAddSource(eventQueue->mMainRunLoop, eventQueue->mRunLoopSource, kCFRunLoopCommonModes);
+    CFRunLoopAddSource(CFRunLoopGetCurrent(), eventQueue->mRunLoopSource, kCFRunLoopCommonModes);
 
 #elif defined(MAC_USE_CARBON_EVENT)
     eventQueue->eventHandlerUPP = NewEventHandlerUPP(_md_EventReceiverProc);