diff --git a/content/base/public/nsIDocument.h b/content/base/public/nsIDocument.h
index c6770279709..2edbf495dd2 100644
--- a/content/base/public/nsIDocument.h
+++ b/content/base/public/nsIDocument.h
@@ -855,6 +855,24 @@ public:
    */
   virtual PRBool MutationEventBeingDispatched() = 0;
 
+  /**
+   * Marks as not-going-to-be-collected for the given generation of
+   * cycle collection.
+   */
+  void MarkUncollectableForCCGeneration(PRUint32 aGeneration)
+  {
+    mMarkedCCGeneration = aGeneration;
+  }
+
+  /**
+   * Gets the cycle collector generation this document is marked for.
+   */
+  PRUint32 GetMarkedCCGeneration()
+  {
+    return mMarkedCCGeneration;
+  }
+  
+
 protected:
   ~nsIDocument()
   {
@@ -927,6 +945,10 @@ protected:
   // if this document is part of a multipart document,
   // the ID can be used to distinguish it from the other parts.
   PRUint32 mPartID;
+  
+  // Cycle collector generation in which we're certain that this document
+  // won't be collected
+  PRUint32 mMarkedCCGeneration;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIDocument, NS_IDOCUMENT_IID)
diff --git a/content/base/public/nsINode.h b/content/base/public/nsINode.h
index 66c4833c3b2..d95b4dd8ac8 100644
--- a/content/base/public/nsINode.h
+++ b/content/base/public/nsINode.h
@@ -82,11 +82,16 @@ class nsNodeSupportsWeakRefTearoff;
 // NOTE: Should only be used on nsIContent nodes
 #define NODE_MAY_HAVE_FRAME          0x00000020U
 
+// Whether the 'in doc' flag is faked to true for
+// this node. This should only ever be set on XUL
+// elements.
+#define NODE_HAS_FAKED_INDOC         0x00000040U
+
 // Four bits for the script-type ID
-#define NODE_SCRIPT_TYPE_OFFSET                6
+#define NODE_SCRIPT_TYPE_OFFSET                7
 
 // Remaining bits are node type specific.
-#define NODE_TYPE_SPECIFIC_BITS_OFFSET       0x0a
+#define NODE_TYPE_SPECIFIC_BITS_OFFSET       0x0b
 
 // Useful macro for getting a node given an nsIContent and an nsIDocument
 // Returns the first argument cast to nsINode if it is non-null, otherwise
diff --git a/content/base/src/Makefile.in b/content/base/src/Makefile.in
index a88535f5f72..96189689c82 100644
--- a/content/base/src/Makefile.in
+++ b/content/base/src/Makefile.in
@@ -76,7 +76,9 @@ REQUIRES	= xpcom \
 		  uriloader \
 		  rdf \
 		  xultmpl \
- 		  util \
+		  util \
+		  appshell \
+		  shistory \
 		  $(NULL)
 
 EXPORTS		= \
@@ -100,6 +102,7 @@ CPPSRCS		= \
 		nsAtomListUtils.cpp \
 		nsAttrAndChildArray.cpp \
 		nsAttrValue.cpp \
+		nsCCUncollectableMarker.cpp \
 		nsCommentNode.cpp \
 		nsContentAreaDragDrop.cpp \
 		nsContentIterator.cpp \
diff --git a/content/base/src/nsCCUncollectableMarker.cpp b/content/base/src/nsCCUncollectableMarker.cpp
index 63303f810f0..f8008d47e19 100644
--- a/content/base/src/nsCCUncollectableMarker.cpp
+++ b/content/base/src/nsCCUncollectableMarker.cpp
@@ -73,6 +73,9 @@ nsCCUncollectableMarker::Init()
   NS_ENSURE_SUCCESS(rv, rv);
 
   // This makes the observer service hold an owning reference to the marker
+  rv = obs->AddObserver(marker, "xpcom-shutdown", PR_FALSE);
+  NS_ENSURE_SUCCESS(rv, rv);
+
   rv = obs->AddObserver(marker, "cycle-collector-begin", PR_FALSE);
   NS_ENSURE_SUCCESS(rv, rv);
 
@@ -183,11 +186,30 @@ nsresult
 nsCCUncollectableMarker::Observe(nsISupports* aSubject, const char* aTopic,
                                  const PRUnichar* aData)
 {
+  nsresult rv;
+
+  if (!strcmp(aTopic, "xpcom-shutdown")) {
+    nsCOMPtr<nsIObserverService> obs =
+      do_GetService("@mozilla.org/observer-service;1", &rv);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    // No need for kungFuDeathGrip here, yay observerservice!
+    obs->RemoveObserver(this, "xpcom-shutdown");
+    obs->RemoveObserver(this, "cycle-collector-begin");
+    
+    sGeneration = 0;
+    
+    return NS_OK;
+  }
+
+  NS_ASSERTION(!strcmp(aTopic, "cycle-collector-begin"), "wrong topic");
+
   // Increase generation to effectivly unmark all current objects
-  ++sGeneration;
+  if (!++sGeneration) {
+    ++sGeneration;
+  }
 
   // Iterate all toplevel windows
-  nsresult rv;
   nsCOMPtr<nsISimpleEnumerator> windowList;
   nsCOMPtr<nsIWindowMediator> med =
     do_GetService(NS_WINDOWMEDIATOR_CONTRACTID);
@@ -206,5 +228,7 @@ nsCCUncollectableMarker::Observe(nsISupports* aSubject, const char* aTopic,
 
     MarkWindowList(windowList);
   }
+
+  return NS_OK;
 }
 
diff --git a/content/base/src/nsCCUncollectableMarker.h b/content/base/src/nsCCUncollectableMarker.h
index 822ff75ea68..bc14d6cbecf 100644
--- a/content/base/src/nsCCUncollectableMarker.h
+++ b/content/base/src/nsCCUncollectableMarker.h
@@ -51,7 +51,7 @@ class nsCCUncollectableMarker : public nsIObserver
    * Checks if we're collecting during a given generation
    */
   static PRBool InGeneration(PRUint32 aGeneration) {
-    return aGeneration == sGeneration;
+    return aGeneration && aGeneration == sGeneration;
   }
 
   static PRUint32 sGeneration;
diff --git a/content/base/src/nsDocument.cpp b/content/base/src/nsDocument.cpp
index bd271cb88a2..efc3bc91fdc 100644
--- a/content/base/src/nsDocument.cpp
+++ b/content/base/src/nsDocument.cpp
@@ -153,6 +153,7 @@ static NS_DEFINE_CID(kDOMEventGroupCID, NS_DOMEVENTGROUP_CID);
 #include "nsIJSContextStack.h"
 #include "nsIXPConnect.h"
 #include "nsCycleCollector.h"
+#include "nsCCUncollectableMarker.h"
 
 #ifdef MOZ_LOGGING
 // so we can get logging even in release builds
@@ -1010,6 +1011,10 @@ LinkMapTraverser(nsUint32ToContentHashEntry* aEntry, void* userArg)
 }
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsDocument)
+  if (nsCCUncollectableMarker::InGeneration(tmp->GetMarkedCCGeneration())) {
+    return NS_OK;
+  }
+
   // Traverse the mChildren nsAttrAndChildArray.
   for (PRInt32 indx = PRInt32(tmp->mChildren.ChildCount()); indx > 0; --indx) {
     cb.NoteXPCOMChild(tmp->mChildren.ChildAt(indx - 1));
diff --git a/content/base/src/nsGenericElement.cpp b/content/base/src/nsGenericElement.cpp
index d80dfd5deb8..7cfdfa8acfb 100644
--- a/content/base/src/nsGenericElement.cpp
+++ b/content/base/src/nsGenericElement.cpp
@@ -117,6 +117,7 @@
 
 
 #include "nsCycleCollectionParticipant.h"
+#include "nsCCUncollectableMarker.h"
 
 #ifdef MOZ_SVG
 PRBool NS_SVG_TestFeature(const nsAString &fstr);
@@ -3007,6 +3008,13 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsGenericElement)
 NS_IMPL_CYCLE_COLLECTION_UNLINK_END
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsGenericElement)
+  nsIDocument* currentDoc = tmp->GetCurrentDoc();
+  if (currentDoc && !tmp->HasFlag(NODE_HAS_FAKED_INDOC) &&
+      nsCCUncollectableMarker::InGeneration(
+        currentDoc->GetMarkedCCGeneration())) {
+    return NS_OK;
+  }
+
   nsIDocument* ownerDoc = tmp->GetOwnerDoc();
   if (ownerDoc) {
     ownerDoc->BindingManager()->Traverse(tmp, cb);
diff --git a/content/base/src/nsNodeUtils.cpp b/content/base/src/nsNodeUtils.cpp
index c38e8f6b885..76d499dd620 100755
--- a/content/base/src/nsNodeUtils.cpp
+++ b/content/base/src/nsNodeUtils.cpp
@@ -547,6 +547,7 @@ nsNodeUtils::CloneAndAdopt(nsINode *aNode, PRBool aClone, PRBool aDeep,
     nsXULElement *xulElem = NS_STATIC_CAST(nsXULElement*, elem);
     if (!xulElem->mPrototype || xulElem->IsInDoc()) {
       clone->mParentPtrBits |= nsINode::PARENT_BIT_INDOCUMENT;
+      clone->SetFlags(NODE_HAS_FAKED_INDOC);
     }
   }
 #endif
diff --git a/content/xul/content/src/nsXULElement.cpp b/content/xul/content/src/nsXULElement.cpp
index 02101ec97af..38a4700d900 100644
--- a/content/xul/content/src/nsXULElement.cpp
+++ b/content/xul/content/src/nsXULElement.cpp
@@ -867,6 +867,9 @@ nsXULElement::BindToTree(nsIDocument* aDocument, nsIContent* aParent,
 
         // Being added to a document.
         mParentPtrBits |= PARENT_BIT_INDOCUMENT;
+
+        // Unset this flag since we now really are in a document.
+        UnsetFlags(NODE_HAS_FAKED_INDOC);
     }
 
     // Now recurse into our kids
diff --git a/dom/src/base/Makefile.in b/dom/src/base/Makefile.in
index 3c13bdb0463..6cbe78e8483 100644
--- a/dom/src/base/Makefile.in
+++ b/dom/src/base/Makefile.in
@@ -123,6 +123,7 @@ LOCAL_INCLUDES = \
 		-I$(topsrcdir)/content/xbl/src \
 		-I$(topsrcdir)/content/xul/document/src \
 		-I$(topsrcdir)/content/events/src \
+		-I$(topsrcdir)/content/base/src \
 		$(NULL)
 
 DEFINES += -D_IMPL_NS_LAYOUT
diff --git a/dom/src/base/nsGlobalWindow.cpp b/dom/src/base/nsGlobalWindow.cpp
index 74234aa9da4..883675352b1 100644
--- a/dom/src/base/nsGlobalWindow.cpp
+++ b/dom/src/base/nsGlobalWindow.cpp
@@ -75,6 +75,7 @@
 #include "nsContentCID.h"
 #include "nsLayoutStatics.h"
 #include "nsCycleCollector.h"
+#include "nsCCUncollectableMarker.h"
 
 // Interfaces Needed
 #include "nsIWidget.h"
@@ -718,6 +719,11 @@ NS_IMPL_CYCLE_COLLECTING_RELEASE_AMBIGUOUS(nsGlobalWindow,
 
 
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsGlobalWindow)
+  if (tmp->mDoc && nsCCUncollectableMarker::InGeneration(
+                     tmp->mDoc->GetMarkedCCGeneration())) {
+    return NS_OK;
+  }
+
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mContext)
 
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMPTR(mOpener)
diff --git a/layout/build/nsLayoutStatics.cpp b/layout/build/nsLayoutStatics.cpp
index b2848d61509..883474b40b0 100644
--- a/layout/build/nsLayoutStatics.cpp
+++ b/layout/build/nsLayoutStatics.cpp
@@ -79,6 +79,7 @@
 #include "nsDOMStorage.h"
 #include "nsCellMap.h"
 #include "nsTextFrameTextRunCache.h"
+#include "nsCCUncollectableMarker.h"
 
 #ifdef MOZ_XUL
 #include "nsXULContentUtils.h"
@@ -216,6 +217,12 @@ nsLayoutStatics::Initialize()
     return rv;
   }
 
+  rv = nsCCUncollectableMarker::Init();
+  if (NS_FAILED(rv)) {
+    NS_ERROR("Could not initialize nsCCUncollectableMarker");
+    return rv;
+  }
+
   return NS_OK;
 }
 
diff --git a/xpcom/base/nsCycleCollector.cpp b/xpcom/base/nsCycleCollector.cpp
index 7a6b4766ed2..83c7b7f0b1f 100644
--- a/xpcom/base/nsCycleCollector.cpp
+++ b/xpcom/base/nsCycleCollector.cpp
@@ -138,6 +138,8 @@
 #include "prtime.h"
 #include "nsPrintfCString.h"
 #include "nsTArray.h"
+#include "nsIObserverService.h"
+#include "nsServiceManagerUtils.h"
 
 #include <stdio.h>
 #ifdef WIN32
@@ -1917,6 +1919,12 @@ nsCycleCollector::Collect(PRUint32 aTryCollections)
     PRTime start = PR_Now(), now;
 #endif
 
+    nsCOMPtr<nsIObserverService> obs =
+      do_GetService("@mozilla.org/observer-service;1");
+    if (obs) {
+        obs->NotifyObservers(nsnull, "cycle-collector-begin", nsnull);
+    }
+
     while (aTryCollections > 0) {
         // This triggers a JS GC. Our caller assumes we always trigger at
         // least one JS GC -- they rely on this fact to avoid redundant JS