diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index b65ddce0b7e..b82b9753518 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -35,8 +35,6 @@ struct PRLogModuleInfo;
 #  define MOZ_LAYERS_LOG(_args)
 #endif  // if defined(DEBUG) || defined(PR_LOGGING)
 
-#define MOZ_ENABLE_MASK_LAYERS
-
 class gfxContext;
 class nsPaintEvent;
 
@@ -697,7 +695,6 @@ public:
    */
   void SetMaskLayer(Layer* aMaskLayer)
   {
-#ifdef MOZ_ENABLE_MASK_LAYERS
 #ifdef DEBUG
     if (aMaskLayer) {
       gfxMatrix maskTransform;
@@ -709,7 +706,6 @@ public:
 
     mMaskLayer = aMaskLayer;
     Mutated();
-#endif
   }
 
   /**
diff --git a/layout/base/FrameLayerBuilder.cpp b/layout/base/FrameLayerBuilder.cpp
index b389e707b8e..a3decf6104f 100644
--- a/layout/base/FrameLayerBuilder.cpp
+++ b/layout/base/FrameLayerBuilder.cpp
@@ -1143,11 +1143,7 @@ ContainerState::ThebesLayerData::UpdateCommonClipCount(
 already_AddRefed<ImageContainer>
 ContainerState::ThebesLayerData::CanOptimizeImageLayer()
 {
-#ifdef MOZ_ENABLE_MASK_LAYERS
   if (!mImage) {
-#else
-  if (!mImage || !mItemClip.mRoundedClipRects.IsEmpty()) {
-#endif
     return nsnull;
   }
 
@@ -1177,10 +1173,6 @@ ContainerState::PopThebesLayerData()
       gfx3DMatrix transform = imageLayer->GetTransform()*
         gfx3DMatrix::ScalingMatrix(mParameters.mXScale, mParameters.mYScale, 1.0f);
       imageLayer->SetTransform(transform);
-#ifndef MOZ_ENABLE_MASK_LAYERS
-      NS_ASSERTION(data->mItemClip.mRoundedClipRects.IsEmpty(),
-                   "How did we get rounded clip rects here?");
-#endif
       if (data->mItemClip.mHaveClipRect) {
         nsIntRect clip = ScaleToNearestPixels(data->mItemClip.mClipRect);
         imageLayer->IntersectClipRect(clip);
@@ -1262,7 +1254,6 @@ ContainerState::PopThebesLayerData()
     }
     userData->mForcedBackgroundColor = backgroundColor;
 
-#ifdef MOZ_ENABLE_MASK_LAYERS
     // use a mask layer for rounded rect clipping
     PRInt32 commonClipCount = data->mCommonClipCount;
     NS_ASSERTION(commonClipCount >= 0, "Inconsistent clip count.");
@@ -1274,7 +1265,6 @@ ContainerState::PopThebesLayerData()
   } else {
     // mask layer for image and color layers
     SetupMaskLayer(layer, data->mItemClip);
-#endif
   }
   PRUint32 flags;
   if (isOpaque && !data->mForceTransparentSurface) {
@@ -1637,13 +1627,7 @@ ContainerState::ProcessDisplayItems(const nsDisplayList& aList,
     // Assign the item to a layer
     if (layerState == LAYER_ACTIVE_FORCE ||
         layerState == LAYER_ACTIVE_EMPTY ||
-#ifdef MOZ_ENABLE_MASK_LAYERS
         layerState == LAYER_ACTIVE) {
-#else
-        (layerState == LAYER_ACTIVE &&
-         (aClip.mRoundedClipRects.IsEmpty() ||
-          !aClip.IsRectClippedByRoundedCorner(item->GetVisibleRect())))) {
-#endif
 
       // LAYER_ACTIVE_EMPTY means the layer is created just for its metadata.
       // We should never see an empty layer with any visible content!
@@ -1705,13 +1689,11 @@ ContainerState::ProcessDisplayItems(const nsDisplayList& aList,
       }
       RestrictVisibleRegionForLayer(ownLayer, itemVisibleRect);
 
-#ifdef MOZ_ENABLE_MASK_LAYERS
       // rounded rectangle clipping using mask layers
       // (must be done after visible rect is set on layer)
       if (aClip.IsRectClippedByRoundedCorner(itemContent)) {
           SetupMaskLayer(ownLayer, aClip);
       }
-#endif
 
       ContainerLayer* oldContainer = ownLayer->GetParent();
       if (oldContainer && oldContainer != mContainerLayer) {
@@ -2830,7 +2812,6 @@ void
 ContainerState::SetupMaskLayer(Layer *aLayer, const FrameLayerBuilder::Clip& aClip,
                                PRUint32 aRoundedRectClipCount) 
 {
-#ifdef MOZ_ENABLE_MASK_LAYERS
   nsIntRect boundingRect = aLayer->GetEffectiveVisibleRegion().GetBounds();
   // don't build an unnecessary mask
   if (aClip.mRoundedClipRects.IsEmpty() ||
@@ -2925,7 +2906,6 @@ ContainerState::SetupMaskLayer(Layer *aLayer, const FrameLayerBuilder::Clip& aCl
   userData->mBounds = aLayer->GetEffectiveVisibleRegion().GetBounds();
 
   aLayer->SetMaskLayer(maskLayer);
-#endif
   return;
 }
 
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index dc07cc1c376..7d9c632afb4 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -1816,12 +1816,6 @@ CanScrollWithBlitting(nsIFrame* aFrame)
         f->IsFrameOfType(nsIFrame::eSVG)) {
       return false;
     }
-#ifndef MOZ_ENABLE_MASK_LAYERS
-    nsIScrollableFrame* sf = do_QueryFrame(f);
-    if ((sf || f->IsFrameOfType(nsIFrame::eReplaced)) &&
-        nsLayoutUtils::HasNonZeroCorner(f->GetStyleBorder()->mBorderRadius))
-      return false;
-#endif
     if (nsLayoutUtils::IsPopup(f))
       break;
   }