diff --git a/mozilla/layout/generic/nsContainerFrame.cpp b/mozilla/layout/generic/nsContainerFrame.cpp
index 7db54d6150f..1dea0123653 100644
--- a/mozilla/layout/generic/nsContainerFrame.cpp
+++ b/mozilla/layout/generic/nsContainerFrame.cpp
@@ -519,6 +519,22 @@ nsContainerFrame::SyncFrameViewAfterReflow(nsIPresContext* aPresContext,
       vm->SetViewContentTransparency(aView, viewHasTransparentContent);
     }
 
+    // Make sure z-index is correct
+    PRInt32                zIndex = 0;
+    PRBool                 autoZIndex = PR_FALSE;
+    const nsStylePosition* position;
+
+    aFrame->GetStyleData(eStyleStruct_Position, (const nsStyleStruct*&)position);
+    if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
+      zIndex = position->mZIndex.GetIntValue();
+
+    } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+      autoZIndex = PR_TRUE;
+    }
+    
+    vm->SetViewZIndex(aView, zIndex);
+    vm->SetViewAutoZIndex(aView, autoZIndex);
+
     // Clip applies to block-level and replaced elements with overflow
     // set to other than 'visible'
     if (display->IsBlockLevel()) {
diff --git a/mozilla/layout/generic/nsHTMLContainerFrame.cpp b/mozilla/layout/generic/nsHTMLContainerFrame.cpp
index ab4863a8c39..bb94bb9ed74 100644
--- a/mozilla/layout/generic/nsHTMLContainerFrame.cpp
+++ b/mozilla/layout/generic/nsHTMLContainerFrame.cpp
@@ -300,6 +300,7 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
   // If we don't yet have a view, see if we need a view
   if (nsnull == view) {
     PRInt32 zIndex = 0;
+    PRBool  autoZIndex = PR_FALSE;
     PRBool  fixedBackgroundAttachment = PR_FALSE;
 
     // Get nsStyleColor and nsStyleDisplay
@@ -336,6 +337,9 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
         // Get the z-index to use
         if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
           zIndex = position->mZIndex.GetIntValue();
+
+        } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+          autoZIndex = PR_TRUE;
         }
       
       } else if (position->IsAbsolutelyPositioned()) {
@@ -347,6 +351,9 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
         // Get the z-index to use
         if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
           zIndex = position->mZIndex.GetIntValue();
+
+        } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+          autoZIndex = PR_TRUE;
         }
       }
     }
@@ -407,6 +414,10 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
           scrollingView->SetScrolledView(view);
         } else {
           viewManager->InsertChild(parentView, view, zIndex);
+
+          if (autoZIndex) {
+            viewManager->SetViewAutoZIndex(view, PR_TRUE);
+          }
         }
 
         // See if the view should be hidden
diff --git a/mozilla/layout/html/base/src/nsContainerFrame.cpp b/mozilla/layout/html/base/src/nsContainerFrame.cpp
index 7db54d6150f..1dea0123653 100644
--- a/mozilla/layout/html/base/src/nsContainerFrame.cpp
+++ b/mozilla/layout/html/base/src/nsContainerFrame.cpp
@@ -519,6 +519,22 @@ nsContainerFrame::SyncFrameViewAfterReflow(nsIPresContext* aPresContext,
       vm->SetViewContentTransparency(aView, viewHasTransparentContent);
     }
 
+    // Make sure z-index is correct
+    PRInt32                zIndex = 0;
+    PRBool                 autoZIndex = PR_FALSE;
+    const nsStylePosition* position;
+
+    aFrame->GetStyleData(eStyleStruct_Position, (const nsStyleStruct*&)position);
+    if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
+      zIndex = position->mZIndex.GetIntValue();
+
+    } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+      autoZIndex = PR_TRUE;
+    }
+    
+    vm->SetViewZIndex(aView, zIndex);
+    vm->SetViewAutoZIndex(aView, autoZIndex);
+
     // Clip applies to block-level and replaced elements with overflow
     // set to other than 'visible'
     if (display->IsBlockLevel()) {
diff --git a/mozilla/layout/html/base/src/nsHTMLContainerFrame.cpp b/mozilla/layout/html/base/src/nsHTMLContainerFrame.cpp
index ab4863a8c39..bb94bb9ed74 100644
--- a/mozilla/layout/html/base/src/nsHTMLContainerFrame.cpp
+++ b/mozilla/layout/html/base/src/nsHTMLContainerFrame.cpp
@@ -300,6 +300,7 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
   // If we don't yet have a view, see if we need a view
   if (nsnull == view) {
     PRInt32 zIndex = 0;
+    PRBool  autoZIndex = PR_FALSE;
     PRBool  fixedBackgroundAttachment = PR_FALSE;
 
     // Get nsStyleColor and nsStyleDisplay
@@ -336,6 +337,9 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
         // Get the z-index to use
         if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
           zIndex = position->mZIndex.GetIntValue();
+
+        } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+          autoZIndex = PR_TRUE;
         }
       
       } else if (position->IsAbsolutelyPositioned()) {
@@ -347,6 +351,9 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
         // Get the z-index to use
         if (position->mZIndex.GetUnit() == eStyleUnit_Integer) {
           zIndex = position->mZIndex.GetIntValue();
+
+        } else if (position->mZIndex.GetUnit() == eStyleUnit_Auto) {
+          autoZIndex = PR_TRUE;
         }
       }
     }
@@ -407,6 +414,10 @@ nsHTMLContainerFrame::CreateViewForFrame(nsIPresContext* aPresContext,
           scrollingView->SetScrolledView(view);
         } else {
           viewManager->InsertChild(parentView, view, zIndex);
+
+          if (autoZIndex) {
+            viewManager->SetViewAutoZIndex(view, PR_TRUE);
+          }
         }
 
         // See if the view should be hidden