diff --git a/content/base/public/nsContentUtils.h b/content/base/public/nsContentUtils.h
index 1b64ba4bb266..14f41a6df04c 100644
--- a/content/base/public/nsContentUtils.h
+++ b/content/base/public/nsContentUtils.h
@@ -81,6 +81,7 @@ class nsIURI;
 class imgIDecoderObserver;
 class imgIRequest;
 class imgILoader;
+class imgICache;
 class nsIPrefBranch;
 class nsIImage;
 class nsIImageLoadingContent;
@@ -647,6 +648,11 @@ public:
                             PRInt32 aLoadFlags,
                             imgIRequest** aRequest);
 
+  /**
+   * Returns whether the given URI is in the image cache.
+   */
+  static PRBool IsImageInCache(nsIURI* aURI);
+
   /**
    * Method to get an nsIImage from an image loading content
    *
@@ -1504,6 +1510,7 @@ private:
   static nsIPref *sPref;
 
   static imgILoader* sImgLoader;
+  static imgICache* sImgCache;
 
   static nsIConsoleService* sConsoleService;
 
diff --git a/content/base/public/nsIDocument.h b/content/base/public/nsIDocument.h
index ef180e5c9717..37197b9228ec 100644
--- a/content/base/public/nsIDocument.h
+++ b/content/base/public/nsIDocument.h
@@ -105,8 +105,8 @@ class nsIBoxObject;
 
 // IID for the nsIDocument interface
 #define NS_IDOCUMENT_IID      \
-  {0x2c155ed0, 0x3302, 0x4cff, \
-      {0x9d, 0xb3, 0xed, 0x0c, 0xcd, 0xfc, 0x50, 0x06 } }
+  { 0x46003091, 0x7f99, 0x420f, \
+  { 0x95, 0xbc, 0x28, 0xd7, 0xd5, 0x01, 0x5a, 0x41 } }
 
 // Flag for AddStyleSheet().
 #define NS_STYLESHEET_FROM_CATALOG                (1 << 0)
@@ -1148,6 +1148,14 @@ public:
   PRUint32 EventHandlingSuppressed() const { return mEventsSuppressed; }
 
   PRBool IsDNSPrefetchAllowed() const { return mAllowDNSPrefetch; }
+
+  /**
+   * Called by nsParser to preload images. Can be removed and code moved
+   * to nsPreloadURIs::PreloadURIs() in file nsParser.cpp whenever the
+   * parser-module is linked with gklayout-module.
+   */
+  virtual void MaybePreLoadImage(nsIURI* uri) = 0;
+
 protected:
   ~nsIDocument()
   {
diff --git a/content/base/src/nsContentUtils.cpp b/content/base/src/nsContentUtils.cpp
index e0a32d48a204..64c77e483698 100644
--- a/content/base/src/nsContentUtils.cpp
+++ b/content/base/src/nsContentUtils.cpp
@@ -179,6 +179,7 @@ static NS_DEFINE_CID(kXTFServiceCID, NS_XTFSERVICE_CID);
 #include "nsIConsoleService.h"
 
 #include "mozAutoDocUpdate.h"
+#include "imgICache.h"
 #include "jsinterp.h"
 
 const char kLoadAsData[] = "loadAsData";
@@ -200,6 +201,7 @@ nsIXTFService *nsContentUtils::sXTFService = nsnull;
 nsIPrefBranch *nsContentUtils::sPrefBranch = nsnull;
 nsIPref *nsContentUtils::sPref = nsnull;
 imgILoader *nsContentUtils::sImgLoader;
+imgICache *nsContentUtils::sImgCache;
 nsIConsoleService *nsContentUtils::sConsoleService;
 nsDataHashtable<nsISupportsHashKey, EventNameMapping>* nsContentUtils::sEventTable = nsnull;
 nsIStringBundleService *nsContentUtils::sStringBundleService;
@@ -330,6 +332,10 @@ nsContentUtils::Init()
   if (NS_FAILED(rv)) {
     // no image loading for us.  Oh, well.
     sImgLoader = nsnull;
+    sImgCache = nsnull;
+  } else {
+    if (NS_FAILED(CallGetService("@mozilla.org/image/cache;1", &sImgCache )))
+      sImgCache = nsnull;
   }
 
   sPtrsToPtrsToRelease = new nsTArray<nsISupports**>();
@@ -893,6 +899,7 @@ nsContentUtils::Shutdown()
   NS_IF_RELEASE(sXTFService);
 #endif
   NS_IF_RELEASE(sImgLoader);
+  NS_IF_RELEASE(sImgCache);
   NS_IF_RELEASE(sPrefBranch);
   NS_IF_RELEASE(sPref);
 #ifdef IBMBIDI
@@ -2383,6 +2390,19 @@ nsContentUtils::CanLoadImage(nsIURI* aURI, nsISupports* aContext,
   return NS_FAILED(rv) ? PR_FALSE : NS_CP_ACCEPTED(decision);
 }
 
+// static
+PRBool
+nsContentUtils::IsImageInCache(nsIURI* aURI)
+{
+    if (!sImgCache) return PR_FALSE;
+
+    // If something unexpected happened we return false, otherwise if props
+    // is set, the image is cached and we return true
+    nsCOMPtr<nsIProperties> props;
+    nsresult rv = sImgCache->FindEntryProperties(aURI, getter_AddRefs(props));
+    return (NS_SUCCEEDED(rv) && props);
+}
+
 // static
 nsresult
 nsContentUtils::LoadImage(nsIURI* aURI, nsIDocument* aLoadingDocument,
diff --git a/content/base/src/nsDocument.cpp b/content/base/src/nsDocument.cpp
index 022b9c88013b..ca0bc37f6664 100644
--- a/content/base/src/nsDocument.cpp
+++ b/content/base/src/nsDocument.cpp
@@ -1780,6 +1780,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(nsDocument)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mStyleSheets)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mCatalogSheets)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mVisitednessChangedURIs)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_NSCOMARRAY(mPreloadingImages)
 
 #ifdef MOZ_SMIL
   // Traverse animation components
@@ -1824,6 +1825,8 @@ NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(nsDocument)
 
   tmp->mParentDocument = nsnull;
 
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_NSCOMARRAY(mPreloadingImages)
+
   // nsDocument has a pretty complex destructor, so we're going to
   // assume that *most* cycles you actually want to break somewhere
   // else, and not unlink an awful lot here.
@@ -3863,6 +3866,9 @@ nsDocument::DispatchContentLoadedEvents()
   // If you add early returns from this method, make sure you're
   // calling UnblockOnload properly.
   
+  // Unpin references to preloaded images
+  mPreloadingImages.Clear();
+    
   // Fire a DOM event notifying listeners that this document has been
   // loaded (excluding images and other loads initiated by this
   // document).
@@ -7485,6 +7491,34 @@ FireOrClearDelayedEvents(nsTArray<nsCOMPtr<nsIDocument> >& aDocuments,
   }
 }
 
+void
+nsDocument::MaybePreLoadImage(nsIURI* uri)
+{
+  // Early exit if the img is already present in the img-cache
+  // which indicates that the "real" load has already started and
+  // that we shouldn't preload it.
+  if (nsContentUtils::IsImageInCache(uri)) {
+    return;
+  }
+
+  // Image not in cache - trigger preload
+  nsCOMPtr<imgIRequest> request;
+  nsresult rv =
+    nsContentUtils::LoadImage(uri,
+                              this,
+                              NodePrincipal(),
+                              mDocumentURI, // uri of document used as referrer
+                              nsnull,       // no observer
+                              nsIRequest::LOAD_NORMAL,
+                              getter_AddRefs(request));
+
+  // Pin image-reference to avoid evicting it from the img-cache before
+  // the "real" load occurs. Unpinned in DispatchContentLoadedEvents and
+  // unlink
+  if (NS_SUCCEEDED(rv)) {
+    mPreloadingImages.AppendObject(request);
+  }
+}
 class nsDelayedEventDispatcher : public nsRunnable
 {
 public:
diff --git a/content/base/src/nsDocument.h b/content/base/src/nsDocument.h
index 7cb0380810f7..a85e577eaeda 100644
--- a/content/base/src/nsDocument.h
+++ b/content/base/src/nsDocument.h
@@ -116,6 +116,7 @@
 #include "nsIProgressEventSink.h"
 #include "nsISecurityEventSink.h"
 #include "nsIChannelEventSink.h"
+#include "imgIRequest.h"
 
 #define XML_DECLARATION_BITS_DECLARATION_EXISTS   (1 << 0)
 #define XML_DECLARATION_BITS_ENCODING_EXISTS      (1 << 1)
@@ -1006,6 +1007,8 @@ public:
   void MaybeInitializeFinalizeFrameLoaders();
 
   void MaybeEndOutermostXBLUpdate();
+
+  virtual void MaybePreLoadImage(nsIURI* uri);
 protected:
 
   void RegisterNamedItems(nsIContent *aContent);
@@ -1264,6 +1267,9 @@ private:
 
   nsExternalResourceMap mExternalResourceMap;
 
+  // All images in process of being preloaded
+  nsCOMArray<imgIRequest> mPreloadingImages;
+
 #ifdef MOZ_SMIL
   nsAutoPtr<nsSMILAnimationController> mAnimationController;
 #endif // MOZ_SMIL
diff --git a/parser/htmlparser/src/nsParser.cpp b/parser/htmlparser/src/nsParser.cpp
index b9449ba0d878..190fefbe66fc 100644
--- a/parser/htmlparser/src/nsParser.cpp
+++ b/parser/htmlparser/src/nsParser.cpp
@@ -382,6 +382,9 @@ nsPreloadURIs::PreloadURIs(const nsAutoTArray<nsSpeculativeScriptThread::Prefetc
       case nsSpeculativeScriptThread::SCRIPT:
         doc->ScriptLoader()->PreloadURI(uri, pe.charset, pe.elementType);
         break;
+      case nsSpeculativeScriptThread::IMAGE:
+        doc->MaybePreLoadImage(uri);
+        break;
       case nsSpeculativeScriptThread::STYLESHEET: {
         nsCOMPtr<nsICSSLoaderObserver> obs = new nsDummyCSSLoaderObserver();
         doc->CSSLoader()->LoadSheet(uri, doc->NodePrincipal(),
@@ -389,9 +392,6 @@ nsPreloadURIs::PreloadURIs(const nsAutoTArray<nsSpeculativeScriptThread::Prefetc
                                     obs);
         break;
       }
-      case nsSpeculativeScriptThread::IMAGE:
-        NS_NOTREACHED("We don't scan these yet");
-        break;
       case nsSpeculativeScriptThread::NONE:
         NS_NOTREACHED("Uninitialized preload entry?");
         break;
@@ -601,6 +601,10 @@ nsSpeculativeScriptThread::ProcessToken(CToken *aToken)
               ptype = STYLESHEET;
               break;
 
+          case eHTMLTag_img:
+              ptype = IMAGE;
+              break;
+
           case eHTMLTag_script:
               ptype = SCRIPT;
               break;