diff --git a/js/xpconnect/src/XPCJSRuntime.cpp b/js/xpconnect/src/XPCJSRuntime.cpp
index da169a7b91fa..6309252f9b6e 100644
--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -302,20 +302,9 @@ void XPCJSRuntime::TraceBlackJS(JSTracer* trc, void* data)
     // Skip this part if XPConnect is shutting down. We get into
     // bad locking problems with the thread iteration otherwise.
     if (!self->GetXPConnect()->IsShuttingDown()) {
-        Mutex* threadLock = XPCPerThreadData::GetLock();
-        if (threadLock)
-        { // scoped lock
-            MutexAutoLock lock(*threadLock);
-
-            XPCPerThreadData* iterp = nsnull;
-            XPCPerThreadData* thread;
-
-            while (nsnull != (thread =
-                              XPCPerThreadData::IterateThreads(&iterp))) {
-                // Trace those AutoMarkingPtr lists!
-                thread->TraceJS(trc);
-            }
-        }
+        // Trace those AutoMarkingPtr lists!
+        if (AutoMarkingPtr *roots = Get()->mAutoRoots)
+            roots->TraceJSAll(trc);
     }
 
     {
@@ -709,29 +698,27 @@ XPCJSRuntime::FinalizeCallback(JSFreeOp *fop, JSFinalizeStatus status, JSBool is
                     XPCPerThreadData* iterp = nsnull;
                     XPCPerThreadData* thread;
 
-                    while (nsnull != (thread =
-                                      XPCPerThreadData::IterateThreads(&iterp))) {
-                        // Mark those AutoMarkingPtr lists!
-                        thread->MarkAutoRootsAfterJSFinalize();
+                    // Mark those AutoMarkingPtr lists!
+                    if (AutoMarkingPtr *roots = Get()->mAutoRoots)
+                        roots->MarkAfterJSFinalizeAll();
 
-                        XPCCallContext* ccxp = XPCJSRuntime::Get()->GetCallContext();
-                        while (ccxp) {
-                            // Deal with the strictness of callcontext that
-                            // complains if you ask for a set when
-                            // it is in a state where the set could not
-                            // possibly be valid.
-                            if (ccxp->CanGetSet()) {
-                                XPCNativeSet* set = ccxp->GetSet();
-                                if (set)
-                                    set->Mark();
-                            }
-                            if (ccxp->CanGetInterface()) {
-                                XPCNativeInterface* iface = ccxp->GetInterface();
-                                if (iface)
-                                    iface->Mark();
-                            }
-                            ccxp = ccxp->GetPrevCallContext();
+                    XPCCallContext* ccxp = XPCJSRuntime::Get()->GetCallContext();
+                    while (ccxp) {
+                        // Deal with the strictness of callcontext that
+                        // complains if you ask for a set when
+                        // it is in a state where the set could not
+                        // possibly be valid.
+                        if (ccxp->CanGetSet()) {
+                            XPCNativeSet* set = ccxp->GetSet();
+                            if (set)
+                                set->Mark();
                         }
+                        if (ccxp->CanGetInterface()) {
+                            XPCNativeInterface* iface = ccxp->GetInterface();
+                            if (iface)
+                                iface->Mark();
+                        }
+                        ccxp = ccxp->GetPrevCallContext();
                     }
                 }
             }
@@ -1948,6 +1935,7 @@ XPCJSRuntime::XPCJSRuntime(nsXPConnect* aXPConnect)
    mJSContextStack(new XPCJSContextStack()),
    mJSCycleCollectionContext(nsnull),
    mCallContext(nsnull),
+   mAutoRoots(nsnull),
    mWrappedJSMap(JSObject2WrappedJSMap::newMap(XPC_JS_MAP_SIZE)),
    mWrappedJSClassMap(IID2WrappedJSClassMap::newMap(XPC_JS_CLASS_MAP_SIZE)),
    mIID2NativeInterfaceMap(IID2NativeInterfaceMap::newMap(XPC_NATIVE_INTERFACE_MAP_SIZE)),
diff --git a/js/xpconnect/src/XPCThreadContext.cpp b/js/xpconnect/src/XPCThreadContext.cpp
index 31f676480091..7b5ce2b1fbe6 100644
--- a/js/xpconnect/src/XPCThreadContext.cpp
+++ b/js/xpconnect/src/XPCThreadContext.cpp
@@ -243,8 +243,7 @@ void *            XPCPerThreadData::sMainJSThread   = nsnull;
 XPCPerThreadData::XPCPerThreadData() :
         mNextThread(nsnull),
         mResolveName(JSID_VOID),
-        mResolvingWrapper(nsnull),
-        mAutoRoots(nsnull)
+        mResolvingWrapper(nsnull)
 #ifdef XPC_CHECK_WRAPPER_THREADSAFETY
       , mWrappedNativeThreadsafetyReportDepth(0)
 #endif
@@ -260,7 +259,6 @@ XPCPerThreadData::XPCPerThreadData() :
 void
 XPCPerThreadData::Cleanup()
 {
-    MOZ_ASSERT(!mAutoRoots);
 }
 
 XPCPerThreadData::~XPCPerThreadData()
@@ -306,31 +304,6 @@ xpc_ThreadDataDtorCB(void* ptr)
     delete data;
 }
 
-void XPCPerThreadData::TraceJS(JSTracer *trc)
-{
-#ifdef XPC_TRACK_AUTOMARKINGPTR_STATS
-    {
-        static int maxLength = 0;
-        int length = 0;
-        for (AutoMarkingPtr* p = mAutoRoots; p; p = p->GetNext())
-            length++;
-        if (length > maxLength)
-            maxLength = length;
-        printf("XPC gc on thread %x with %d AutoMarkingPtrs (%d max so far)\n",
-               this, length, maxLength);
-    }
-#endif
-
-    if (mAutoRoots)
-        mAutoRoots->TraceJSAll(trc);
-}
-
-void XPCPerThreadData::MarkAutoRootsAfterJSFinalize()
-{
-    if (mAutoRoots)
-        mAutoRoots->MarkAfterJSFinalizeAll();
-}
-
 // static
 XPCPerThreadData*
 XPCPerThreadData::GetDataImpl(JSContext *cx)
diff --git a/js/xpconnect/src/xpcprivate.h b/js/xpconnect/src/xpcprivate.h
index c8075d95878a..357f71b8d1d6 100644
--- a/js/xpconnect/src/xpcprivate.h
+++ b/js/xpconnect/src/xpcprivate.h
@@ -855,6 +855,8 @@ public:
 
     size_t SizeOfIncludingThis(nsMallocSizeOfFun mallocSizeOf);
 
+    AutoMarkingPtr**  GetAutoRootsAdr() {return &mAutoRoots;}
+
 private:
     XPCJSRuntime(); // no implementation
     XPCJSRuntime(nsXPConnect* aXPConnect);
@@ -876,6 +878,7 @@ private:
     XPCJSContextStack*       mJSContextStack;
     JSContext*               mJSCycleCollectionContext;
     XPCCallContext*          mCallContext;
+    AutoMarkingPtr*          mAutoRoots;
     JSObject2WrappedJSMap*   mWrappedJSMap;
     IID2WrappedJSClassMap*   mWrappedJSClassMap;
     IID2NativeInterfaceMap*  mIID2NativeInterfaceMap;
@@ -3754,10 +3757,6 @@ public:
     // Must be called with the threads locked.
     static XPCPerThreadData* IterateThreads(XPCPerThreadData** iteratorp);
 
-    AutoMarkingPtr**  GetAutoRootsAdr() {return &mAutoRoots;}
-
-    void TraceJS(JSTracer* trc);
-    void MarkAutoRootsAfterJSFinalize();
 
     static void InitStatics()
         { gLock = nsnull; gThreads = nsnull; gTLSIndex = BAD_TLS_INDEX; }
@@ -3784,8 +3783,6 @@ private:
     jsid                 mResolveName;
     XPCWrappedNative*    mResolvingWrapper;
 
-    AutoMarkingPtr*      mAutoRoots;
-
 #ifdef XPC_CHECK_WRAPPER_THREADSAFETY
     uint32_t             mWrappedNativeThreadsafetyReportDepth;
 #endif
@@ -4035,7 +4032,7 @@ class AutoMarkingPtr
 {
   public:
     AutoMarkingPtr(XPCCallContext& ccx) {
-        mRoot = ccx.GetThreadData()->GetAutoRootsAdr();
+        mRoot = XPCJSRuntime::Get()->GetAutoRootsAdr();
         mNext = *mRoot;
         *mRoot = this;
     }