diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index f7f3a6862134..d69929275c02 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -95,6 +95,9 @@
 #include "nsIDOMXULDocument.h"
 #include "nsIXULDocument.h"
 #endif
+#ifdef MOZ_FLEXBOX
+#include "nsFlexContainerFrame.h"
+#endif
 #ifdef ACCESSIBILITY
 #include "nsAccessibilityService.h"
 #endif
@@ -4293,17 +4296,6 @@ nsCSSFrameConstructor::BuildScrollFrame(nsFrameConstructorState& aState,
     return NS_OK;
 }
 
-#ifdef MOZ_FLEXBOX
-// TEMPORARY CHUNK: No-op constructor, so we can compile at this
-// intermediate state.  Removed in subsequent patch.
-nsIFrame*
-NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
-                         nsStyleContext* aContext)
-{
-  return nsnull;
-}
-#endif // MOZ_FLEXBOX
-
 const nsCSSFrameConstructor::FrameConstructionData*
 nsCSSFrameConstructor::FindDisplayData(const nsStyleDisplay* aDisplay,
                                        Element* aElement,
diff --git a/layout/generic/Makefile.in b/layout/generic/Makefile.in
index 7fa4ecd697da..6a87bfe87e74 100644
--- a/layout/generic/Makefile.in
+++ b/layout/generic/Makefile.in
@@ -93,6 +93,12 @@ CPPSRCS		= \
 		nsViewportFrame.cpp \
 		$(NULL)
 
+ifdef MOZ_FLEXBOX
+CPPSRCS		+= \
+		nsFlexContainerFrame.cpp \
+		$(NULL)
+endif
+
 ifdef MOZ_MEDIA
 CPPSRCS		+= \
 		nsVideoFrame.cpp \
diff --git a/layout/generic/nsFlexContainerFrame.cpp b/layout/generic/nsFlexContainerFrame.cpp
new file mode 100644
index 000000000000..59f65142740e
--- /dev/null
+++ b/layout/generic/nsFlexContainerFrame.cpp
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+
+/* This Source Code is subject to the terms of the Mozilla Public License
+ * version 2.0 (the "License"). You can obtain a copy of the License at
+ * http://mozilla.org/MPL/2.0/. */
+
+/* rendering object for CSS display: -moz-flex */
+
+#include "nsFlexContainerFrame.h"
+#include "nsPresContext.h"
+#include "nsStyleContext.h"
+#include "prlog.h"
+
+#ifdef PR_LOGGING 
+static PRLogModuleInfo* nsFlexContainerFrameLM = PR_NewLogModule("nsFlexContainerFrame");
+#endif /* PR_LOGGING */
+
+NS_IMPL_FRAMEARENA_HELPERS(nsFlexContainerFrame)
+
+nsIFrame*
+NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
+                         nsStyleContext* aContext)
+{
+  return new (aPresShell) nsFlexContainerFrame(aContext);
+}
+
+//----------------------------------------------------------------------
+
+/* virtual */
+nsFlexContainerFrame::~nsFlexContainerFrame()
+{
+}
+
+NS_QUERYFRAME_HEAD(nsFlexContainerFrame)
+  NS_QUERYFRAME_ENTRY(nsFlexContainerFrame)
+NS_QUERYFRAME_TAIL_INHERITING(nsFlexContainerFrameSuper)
+
+void
+nsFlexContainerFrame::DestroyFrom(nsIFrame* aDestructRoot)
+{
+  DestroyAbsoluteFrames(aDestructRoot);
+  nsFlexContainerFrameSuper::DestroyFrom(aDestructRoot);
+}
+
+nsIAtom*
+nsFlexContainerFrame::GetType() const
+{
+  return nsGkAtoms::flexContainerFrame;
+}
+
+#ifdef DEBUG
+NS_IMETHODIMP
+nsFlexContainerFrame::GetFrameName(nsAString& aResult) const
+{
+  return MakeFrameName(NS_LITERAL_STRING("FlexContainer"), aResult);
+}
+#endif // DEBUG
diff --git a/layout/generic/nsFlexContainerFrame.h b/layout/generic/nsFlexContainerFrame.h
new file mode 100644
index 000000000000..dcbbbca46535
--- /dev/null
+++ b/layout/generic/nsFlexContainerFrame.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+
+/* This Source Code is subject to the terms of the Mozilla Public License
+ * version 2.0 (the "License"). You can obtain a copy of the License at
+ * http://mozilla.org/MPL/2.0/. */
+
+/* rendering object for CSS display: -moz-flex */
+
+#ifndef nsFlexContainerFrame_h___
+#define nsFlexContainerFrame_h___
+
+#include "nsContainerFrame.h"
+#include "mozilla/Types.h"
+
+nsIFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
+                                   nsStyleContext* aContext);
+
+typedef nsContainerFrame nsFlexContainerFrameSuper;
+
+class nsFlexContainerFrame : public nsFlexContainerFrameSuper {
+  NS_DECL_FRAMEARENA_HELPERS
+  NS_DECL_QUERYFRAME_TARGET(nsFlexContainerFrame)
+  NS_DECL_QUERYFRAME
+
+  // Factory method:
+  friend nsIFrame* NS_NewFlexContainerFrame(nsIPresShell* aPresShell,
+                                            nsStyleContext* aContext);
+
+  // nsIFrame overrides
+  virtual nsIAtom* GetType() const MOZ_OVERRIDE;
+#ifdef DEBUG
+  NS_IMETHOD GetFrameName(nsAString& aResult) const MOZ_OVERRIDE;
+#endif
+
+protected:
+  // Protected constructor & destructor
+  nsFlexContainerFrame(nsStyleContext* aContext) : nsFlexContainerFrameSuper(aContext) {}
+  virtual ~nsFlexContainerFrame();
+
+  // Protected nsIFrame overrides:
+  virtual void DestroyFrom(nsIFrame* aDestructRoot);
+
+};
+
+#endif /* nsFlexContainerFrame_h___ */
diff --git a/layout/generic/nsFrameIdList.h b/layout/generic/nsFrameIdList.h
index fda8522782c9..f37812b3b1db 100644
--- a/layout/generic/nsFrameIdList.h
+++ b/layout/generic/nsFrameIdList.h
@@ -22,6 +22,9 @@ FRAME_ID(nsFieldSetFrame)
 FRAME_ID(nsFileControlFrame)
 FRAME_ID(nsFirstLetterFrame)
 FRAME_ID(nsFirstLineFrame)
+#ifdef MOZ_FLEXBOX
+FRAME_ID(nsFlexContainerFrame)
+#endif // MOZ_FLEXBOX
 FRAME_ID(nsFormControlFrame)
 FRAME_ID(nsFrame)
 FRAME_ID(nsGfxButtonControlFrame)