diff --git a/gfx/layers/composite/APZCTreeManager.cpp b/gfx/layers/composite/APZCTreeManager.cpp
index 0b2158c98dd7..d87f16d750ff 100644
--- a/gfx/layers/composite/APZCTreeManager.cpp
+++ b/gfx/layers/composite/APZCTreeManager.cpp
@@ -203,7 +203,17 @@ APZCTreeManager::UpdatePanZoomControllerTree(CompositorParent* aCompositor,
         apzc->NotifyLayersUpdated(container->GetFrameMetrics(),
                                   aIsFirstPaint && (aLayersId == aFirstPaintLayersId));
 
+        // Use the composition bounds as the hit test region.
+        // Optionally, the GeckoContentController can provide a touch-sensitive
+        // region that constrains all frames associated with the controller.
+        // In this case we intersect the composition bounds with that region.
         ScreenRect visible(container->GetFrameMetrics().mCompositionBounds);
+        CSSRect touchSensitiveRegion;
+        if (state->mController->GetTouchSensitiveRegion(&touchSensitiveRegion)) {
+          visible = visible.Intersect(touchSensitiveRegion
+                                      * container->GetFrameMetrics().LayersPixelsPerCSSPixel()
+                                      * LayerToScreenScale(1.0));
+        }
         apzc->SetLayerHitTestData(visible, aTransform, aLayer->GetTransform());
         APZC_LOG("Setting rect(%f %f %f %f) as visible region for APZC %p\n", visible.x, visible.y,
                                                                               visible.width, visible.height,
diff --git a/gfx/layers/ipc/GeckoContentController.h b/gfx/layers/ipc/GeckoContentController.h
index a441fe242584..3f0d4577506b 100644
--- a/gfx/layers/ipc/GeckoContentController.h
+++ b/gfx/layers/ipc/GeckoContentController.h
@@ -81,6 +81,22 @@ public:
     return false;
   }
 
+  /**
+   * APZ uses |FrameMetrics::mCompositionBounds| for hit testing. Sometimes,
+   * widget code has knowledge of a touch-sensitive region that should
+   * additionally constrain hit testing for all frames associated with the
+   * controller. This method allows APZ to query the controller for such a
+   * region. A return value of true indicates that the controller has such a
+   * region, and it is returned in |aOutRegion|.
+   * TODO: once bug 928833 is implemented, this should be removed, as
+   * APZ can then get the correct touch-sensitive region for each frame
+   * directly from the layer.
+   */
+  virtual bool GetTouchSensitiveRegion(CSSRect* aOutRegion)
+  {
+    return false;
+  }
+
   /**
    * General tranformation notices for consumers. These fire any time
    * the apzc is modifying the view, including panning, zooming, and
diff --git a/layout/ipc/RenderFrameParent.cpp b/layout/ipc/RenderFrameParent.cpp
index 5a11edfeee73..3356b95bfe75 100644
--- a/layout/ipc/RenderFrameParent.cpp
+++ b/layout/ipc/RenderFrameParent.cpp
@@ -610,12 +610,6 @@ public:
     MessageLoop::current()->PostDelayedTask(FROM_HERE, aTask, aDelayMs);
   }
 
-  void SaveZoomConstraints(const ZoomConstraints& aConstraints)
-  {
-    mHaveZoomConstraints = true;
-    mZoomConstraints = aConstraints;
-  }
-
   virtual bool GetRootZoomConstraints(ZoomConstraints* aOutConstraints)
   {
     if (mHaveZoomConstraints && aOutConstraints) {
@@ -624,6 +618,15 @@ public:
     return mHaveZoomConstraints;
   }
 
+  virtual bool GetTouchSensitiveRegion(CSSRect* aOutRegion)
+  {
+    if (mTouchSensitiveRegion.IsEmpty())
+      return false;
+
+    *aOutRegion = CSSRect::FromAppUnits(mTouchSensitiveRegion.GetBounds());
+    return true;
+  }
+
   virtual void NotifyTransformBegin(const ScrollableLayerGuid& aGuid)
   {
     if (MessageLoop::current() != mUILoop) {
@@ -654,6 +657,18 @@ public:
     }
   }
 
+  // Methods used by RenderFrameParent to set fields stored here.
+
+  void SaveZoomConstraints(const ZoomConstraints& aConstraints)
+  {
+    mHaveZoomConstraints = true;
+    mZoomConstraints = aConstraints;
+  }
+
+  void SetTouchSensitiveRegion(const nsRegion& aRegion)
+  {
+    mTouchSensitiveRegion = aRegion;
+  }
 private:
   void DoRequestContentRepaint(const FrameMetrics& aFrameMetrics)
   {
@@ -668,6 +683,7 @@ private:
 
   bool mHaveZoomConstraints;
   ZoomConstraints mZoomConstraints;
+  nsRegion mTouchSensitiveRegion;
 };
 
 RenderFrameParent::RenderFrameParent()
@@ -941,6 +957,13 @@ bool
 RenderFrameParent::RecvUpdateHitRegion(const nsRegion& aRegion)
 {
   mTouchRegion = aRegion;
+  if (mContentController) {
+    // Tell the content controller about the touch-sensitive region, so
+    // that it can provide it to APZ. This is required for APZ to do
+    // correct hit testing for a remote 'mozpasspointerevents' iframe
+    // until bug 928833 is fixed.
+    mContentController->SetTouchSensitiveRegion(aRegion);
+  }
   return true;
 }