diff --git a/xpcom/components/nsComponentManager.cpp b/xpcom/components/nsComponentManager.cpp
index 632359ffc80..9be70475c4c 100644
--- a/xpcom/components/nsComponentManager.cpp
+++ b/xpcom/components/nsComponentManager.cpp
@@ -1770,56 +1770,35 @@ nsresult
 nsComponentManagerImpl::UnregisterComponentSpec(const nsCID &aClass,
                                                 nsIFile *aLibrarySpec)
 {
-    char *aLibrary;
-    nsresult rv = aLibrarySpec->GetPath(&aLibrary);
-    if (NS_FAILED(rv))
-        return NS_ERROR_INVALID_ARG;
+    nsXPIDLCString registryName;
+    nsresult rv = RegistryLocationForSpec(aLibrarySpec, getter_Copies(registryName));
+    if (NS_FAILED(rv)) return NS_ERROR_INVALID_ARG;
 
-    if (PR_LOG_TEST(nsComponentManagerLog, PR_LOG_ALWAYS))
-    {
-        char *buf = aClass.ToString();
-        PR_LogPrint("nsComponentManager: UnregisterComponentSpec(%s, %s)", buf,
-                    aLibrary);
-        delete [] buf;
-    }
-    	
-    nsIDKey key(aClass);
-    nsFactoryEntry *old = (nsFactoryEntry *) mFactories->Get(&key);
-    	
-    nsresult res = NS_ERROR_FACTORY_NOT_REGISTERED;
-    	
     PR_EnterMonitor(mMon);
-    	
-    if (old != NULL)
+
+    // Remove any stored factory entries
+    nsIDKey key(aClass);
+    nsFactoryEntry *entry = (nsFactoryEntry *) mFactories->Get(&key);
+    if (entry && entry->location && PL_strcasecmp(entry->location, registryName))
     {
-#if 0 /* use nsFactoryEntry->location */
-        if (old->dll->GetPersistentDescriptorString() != NULL &&
-#if defined(XP_UNIX) || defined(XP_BEOS)
-            PL_strcasecmp(old->dll->GetPersistentDescriptorString(), aLibrary)
-#else
-            PL_strcmp(old->dll->GetPersistentDescriptorString(), aLibrary)
-#endif
-            )
-        {
-            mFactories->RemoveAndDelete(&key);
-            old = NULL;
-            res = NS_OK;
-        }
-#ifdef USE_REGISTRY
-        char *cidString = aClass.ToString();
-        res = PlatformUnregister(cidString, aLibrary);
-        delete [] cidString;
-#endif
-#endif
+        mFactories->RemoveAndDelete(&key);
+        entry = NULL;
     }
+
+#ifdef USE_REGISTRY
+    // Remove registry entries for this cid
+    char *cidString = aClass.ToString();
+    rv = PlatformUnregister(cidString, registryName);
+    delete [] cidString;
+#endif
     	
     PR_ExitMonitor(mMon);
     	
     PR_LOG(nsComponentManagerLog, PR_LOG_WARNING,
-           ("nsComponentManager: ! Factory unregister %s.", 
-            NS_SUCCEEDED(res) ? "succeeded" : "failed"));
-    	
-    return res;
+           ("nsComponentManager: Factory unregister(%s) %s.", (const char *)registryName,
+            NS_SUCCEEDED(rv) ? "succeeded" : "FAILED"));
+
+    return rv;
 }
 
 struct CanUnload_closure {
@@ -2037,10 +2016,25 @@ AutoRegisterComponent_enumerate(nsHashKey *key, void *aData, void *aClosure)
 						    &didRegister);
     
     if (NS_SUCCEEDED(closure->status) && didRegister)
-	return PR_FALSE;
-    if (didRegister)
-	return PR_TRUE;
-    return PR_FALSE;
+	return PR_FALSE; // Stop enumeration as we are done
+    return PR_TRUE;
+}
+
+static PRBool
+AutoUnregisterComponent_enumerate(nsHashKey *key, void *aData, void *aClosure)
+{
+    PRBool didUnregister;
+    nsIComponentLoader *loader = (nsIComponentLoader *)aData;
+    struct AutoReg_closure *closure =
+	(struct AutoReg_closure *)aClosure;
+
+    closure->status = loader->AutoUnregisterComponent(closure->when,
+                                                      closure->spec,
+                                                      &didUnregister);
+    if (NS_SUCCEEDED(closure->status) && didUnregister)
+        return PR_FALSE; // Stop enumeration as we are done
+    return PR_TRUE; // Let enumeration continue
+
 }
 
 nsresult
@@ -2064,6 +2058,24 @@ nsComponentManagerImpl::AutoRegisterComponent(PRInt32 when,
 
 }
 
+nsresult
+nsComponentManagerImpl::AutoUnregisterComponent(PRInt32 when,
+                                                nsIFile *component)
+{
+    struct AutoReg_closure closure;
+
+    /* XXX convert when to nsIComponentLoader::(when) properly */
+    closure.when = (PRInt32)when;
+    closure.spec = component;
+    closure.status = NS_OK;
+
+    mLoaders->Enumerate(AutoUnregisterComponent_enumerate, &closure);
+
+    return NS_FAILED(closure.status) 
+	? NS_ERROR_FACTORY_NOT_REGISTERED : NS_OK;
+
+}
+
 nsresult
 nsComponentManagerImpl::IsRegistered(const nsCID &aClass,
                                      PRBool *aRegistered)
diff --git a/xpcom/components/nsComponentManagerUtils.h b/xpcom/components/nsComponentManagerUtils.h
index c265f2bcd8f..a57f95ff9c2 100644
--- a/xpcom/components/nsComponentManagerUtils.h
+++ b/xpcom/components/nsComponentManagerUtils.h
@@ -161,6 +161,7 @@ public:
   // in the default components directory.
   static nsresult AutoRegister(PRInt32 when, nsIFile* directory);
   static nsresult AutoRegisterComponent(PRInt32 when, nsIFile *component);
+  static nsresult AutoUnregisterComponent(PRInt32 when, nsIFile *component);
 
   // Is the given CID currently registered?
   static nsresult IsRegistered(const nsCID &aClass,
diff --git a/xpcom/components/nsIComponentLoader.idl b/xpcom/components/nsIComponentLoader.idl
index ee3943d0dae..cb6cb3b8318 100644
--- a/xpcom/components/nsIComponentLoader.idl
+++ b/xpcom/components/nsIComponentLoader.idl
@@ -1,4 +1,4 @@
-/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  *
  * The contents of this file are subject to the Netscape Public License
  * Version 1.1 (the "NPL"); you may not use this file except in
@@ -68,6 +68,13 @@ interface nsIComponentLoader : nsISupports {
      */
     boolean autoRegisterComponent(in long aWhen, in nsIFile aComponent);
 
+    /**
+     * AutoUnregister the given component.
+     * Returns true if the component was unregistered, false if it coudln't
+     * attempt to unregister the component (not found, wrong type).
+     */
+    boolean autoUnregisterComponent(in long aWhen, in nsIFile aComponent);
+
     /**
      * Register any deferred (NS_ERROR_FACTORY_REGISTER_AGAIN) components.
      * Return registered-any-components?
diff --git a/xpcom/components/nsIComponentManager.idl b/xpcom/components/nsIComponentManager.idl
index a1c656e6c5e..863f2b24504 100644
--- a/xpcom/components/nsIComponentManager.idl
+++ b/xpcom/components/nsIComponentManager.idl
@@ -86,6 +86,7 @@ interface nsIComponentManager : nsISupports
 
     void       autoRegister(in long when, in nsIFile directory);
     void       autoRegisterComponent(in long when, in nsIFile component);
+    void       autoUnregisterComponent(in long when, in nsIFile component);
 
     boolean    isRegistered(in nsCIDRef aClass);
     nsIEnumerator	enumerateCLSIDs();
diff --git a/xpcom/components/nsNativeComponentLoader.cpp b/xpcom/components/nsNativeComponentLoader.cpp
index c9b997c28de..b33a430f83c 100644
--- a/xpcom/components/nsNativeComponentLoader.cpp
+++ b/xpcom/components/nsNativeComponentLoader.cpp
@@ -579,9 +579,6 @@ nsNativeComponentLoader::DumpLoadError(nsDll *dll,
 nsresult
 nsNativeComponentLoader::SelfUnregisterDll(nsDll *dll)
 {
-    // Precondition: dll is not loaded
-    PR_ASSERT(dll->IsLoaded() == PR_FALSE);
-
     nsIServiceManager* serviceMgr = NULL;
     nsresult res = nsServiceManager::GetGlobalServiceManager(&serviceMgr);
     if (NS_FAILED(res)) return res;
@@ -623,10 +620,39 @@ nsNativeComponentLoader::SelfUnregisterDll(nsDll *dll)
         }
     }
 #endif /* OBSOLETE_MODULE_LOADING */
-    dll->Unload();
     return res;
 }
 
+nsresult
+nsNativeComponentLoader::AutoUnregisterComponent(PRInt32 when,
+                                                 nsIFile *component,
+                                                 PRBool *unregistered)
+{
+    nsresult rv = NS_ERROR_FAILURE;
+
+    nsXPIDLCString persistentDescriptor;
+    rv = mCompMgr->RegistryLocationForSpec(component,
+                                           getter_Copies(persistentDescriptor));
+    if (NS_FAILED(rv)) return rv;
+
+    nsDll *dll = NULL;
+    PRInt64 mod = LL_Zero(), size = LL_Zero();
+    rv = CreateDll(component, persistentDescriptor, &mod, &size, &dll);
+    if (NS_FAILED(rv) || dll == NULL) return rv;
+
+    rv = SelfUnregisterDll(dll);
+
+    // Remove any autoreg info about this dll
+    if (NS_SUCCEEDED(rv))
+        RemoveRegistryDllInfo(persistentDescriptor);
+
+    PR_LOG(nsComponentManagerLog, PR_LOG_ERROR,
+           ("nsNativeComponentLoader: AutoUnregistration for %s %s.",
+            (NS_FAILED(rv) ? "FAILED" : "succeeded"), dll->GetDisplayPath()));
+    return rv;
+}
+
+
 nsresult
 nsNativeComponentLoader::AutoRegisterComponent(PRInt32 when,
                                                nsIFile *component,
@@ -940,6 +966,12 @@ nsNativeComponentLoader::SetRegistryDllInfo(const char *aLocation,
     return rv;
 }
 
+nsresult
+nsNativeComponentLoader::RemoveRegistryDllInfo(const char *aLocation)
+{
+    return mRegistry->RemoveSubtree(mXPCOMKey, aLocation);
+}
+
 //
 // CreateDll
 // The only way to create a dll or get it from the dll cache. This will
diff --git a/xpcom/components/nsNativeComponentLoader.h b/xpcom/components/nsNativeComponentLoader.h
index 8625d41196c..957a642e243 100644
--- a/xpcom/components/nsNativeComponentLoader.h
+++ b/xpcom/components/nsNativeComponentLoader.h
@@ -64,6 +64,7 @@ class nsNativeComponentLoader : public nsIComponentLoader {
                                 PRInt64 *fileSize);
     nsresult SetRegistryDllInfo(const char *aLocation, PRInt64 *lastModifiedTime,
                                 PRInt64 *fileSize);
+    nsresult RemoveRegistryDllInfo(const char *aLocation);
     nsresult GetFactoryFromModule(nsDll *aDll, const nsCID &aCID,
                                   nsIFactory **aFactory);
     /* obsolete! already! */
diff --git a/xpcom/components/nsRepository.cpp b/xpcom/components/nsRepository.cpp
index fa0603d8125..84e11bfb18c 100644
--- a/xpcom/components/nsRepository.cpp
+++ b/xpcom/components/nsRepository.cpp
@@ -210,6 +210,16 @@ nsComponentManager::AutoRegisterComponent(PRInt32 when,
     return cm->AutoRegisterComponent(when, fullname);
 }
 
+nsresult
+nsComponentManager::AutoUnregisterComponent(PRInt32 when,
+                                          nsIFile *fullname)
+{
+    nsIComponentManager* cm;
+    nsresult rv = NS_GetGlobalComponentManager(&cm);
+    if (NS_FAILED(rv)) return rv;
+    return cm->AutoUnregisterComponent(when, fullname);
+}
+
 nsresult 
 nsComponentManager::IsRegistered(const nsCID &aClass,
                                  PRBool *aRegistered)
diff --git a/xpcom/glue/nsComponentManagerUtils.h b/xpcom/glue/nsComponentManagerUtils.h
index c265f2bcd8f..a57f95ff9c2 100644
--- a/xpcom/glue/nsComponentManagerUtils.h
+++ b/xpcom/glue/nsComponentManagerUtils.h
@@ -161,6 +161,7 @@ public:
   // in the default components directory.
   static nsresult AutoRegister(PRInt32 when, nsIFile* directory);
   static nsresult AutoRegisterComponent(PRInt32 when, nsIFile *component);
+  static nsresult AutoUnregisterComponent(PRInt32 when, nsIFile *component);
 
   // Is the given CID currently registered?
   static nsresult IsRegistered(const nsCID &aClass,