diff --git a/gfx/layers/Layers.cpp b/gfx/layers/Layers.cpp
index 2f1d855016cf..1d619180efd6 100644
--- a/gfx/layers/Layers.cpp
+++ b/gfx/layers/Layers.cpp
@@ -456,6 +456,9 @@ Layer::PrintInfo(nsACString& aTo, const char* aPrefix)
   if (1.0 != mOpacity) {
     aTo.AppendPrintf(" [opacity=%g]", mOpacity);
   }
+  if (const nsIntRect* tileSourceRect = GetTileSourceRect()) {
+    AppendToString(aTo, *tileSourceRect, " [tileSrc=", "]");
+  }
   if (GetContentFlags() & CONTENT_OPAQUE) {
     aTo += " [opaqueContent]";
   }
diff --git a/gfx/layers/Layers.h b/gfx/layers/Layers.h
index 948b69c7b011..927c0c1bc75c 100644
--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -622,6 +622,35 @@ public:
     Mutated();
   }
 
+  /**
+   * CONSTRUCTION PHASE ONLY
+   *
+   * Define a subrect of this layer that will be used as the source
+   * image for tiling this layer's visible region.  The coordinates
+   * are in the un-transformed space of this layer (i.e. the visible
+   * region of this this layer is tiled before being transformed).
+   * The visible region is tiled "outwards" from the source rect; that
+   * is, the source rect is drawn "in place", then repeated to cover
+   * the layer's visible region.
+   *
+   * The interpretation of the source rect varies depending on
+   * underlying layer type.  For ImageLayers and CanvasLayers, it
+   * doesn't make sense to set a source rect not fully contained by
+   * the bounds of their underlying images.  For ThebesLayers, thebes
+   * content may need to be rendered to fill the source rect.  For
+   * ColorLayers, a source rect for tiling doesn't make sense at all.
+   *
+   * If aRect is null no tiling will be performed. 
+   */
+  void SetTileSourceRect(const nsIntRect* aRect)
+  {
+    mUseTileSourceRect = aRect != nsnull;
+    if (aRect) {
+      mTileSourceRect = *aRect;
+    }
+    Mutated();
+  }
+
   // These getters can be used anytime.
   float GetOpacity() { return mOpacity; }
   const nsIntRect* GetClipRect() { return mUseClipRect ? &mClipRect : nsnull; }
@@ -633,6 +662,7 @@ public:
   virtual Layer* GetFirstChild() { return nsnull; }
   virtual Layer* GetLastChild() { return nsnull; }
   const gfx3DMatrix& GetTransform() { return mTransform; }
+  const nsIntRect* GetTileSourceRect() { return mUseTileSourceRect ? &mTileSourceRect : nsnull; }
 
   /**
    * DRAWING PHASE ONLY
@@ -792,7 +822,8 @@ protected:
     mImplData(aImplData),
     mOpacity(1.0),
     mContentFlags(0),
-    mUseClipRect(PR_FALSE)
+    mUseClipRect(PR_FALSE),
+    mUseTileSourceRect(PR_FALSE)
     {}
 
   void Mutated() { mManager->Mutated(this); }
@@ -836,8 +867,10 @@ protected:
   gfx3DMatrix mEffectiveTransform;
   float mOpacity;
   nsIntRect mClipRect;
+  nsIntRect mTileSourceRect;
   PRUint32 mContentFlags;
   PRPackedBool mUseClipRect;
+  PRPackedBool mUseTileSourceRect;
 };
 
 /**