diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index ec47e9b0daf2..f2d4016bb1cf 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -9,11 +9,12 @@
  * boxes, also used for various anonymous boxes
  */
 
+#include "nsBlockFrame.h"
+
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Util.h"
 
 #include "nsCOMPtr.h"
-#include "nsBlockFrame.h"
 #include "nsAbsoluteContainingBlock.h"
 #include "nsBlockReflowContext.h"
 #include "nsBlockReflowState.h"
diff --git a/layout/generic/nsBlockReflowState.cpp b/layout/generic/nsBlockReflowState.cpp
index daafd017b715..5c6b05b838c8 100644
--- a/layout/generic/nsBlockReflowState.cpp
+++ b/layout/generic/nsBlockReflowState.cpp
@@ -6,6 +6,8 @@
 
 /* state used in reflow of block frames */
 
+#include "nsBlockReflowState.h"
+
 #include "mozilla/DebugOnly.h"
 
 #include "nsBlockFrame.h"
diff --git a/layout/generic/nsBulletFrame.cpp b/layout/generic/nsBulletFrame.cpp
index 4fb8d3e4cd4c..64fcd753e6cb 100644
--- a/layout/generic/nsBulletFrame.cpp
+++ b/layout/generic/nsBulletFrame.cpp
@@ -5,8 +5,9 @@
 
 /* rendering object for list-item bullets */
 
-#include "nsCOMPtr.h"
 #include "nsBulletFrame.h"
+
+#include "nsCOMPtr.h"
 #include "nsGkAtoms.h"
 #include "nsGenericHTMLElement.h"
 #include "nsAttrValueInlines.h"
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 3cfda53e9b6d..01e1106003f2 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -6,11 +6,12 @@
 
 /* base class of all rendering objects */
 
+#include "nsFrame.h"
+
 #include "mozilla/Attributes.h"
 #include "mozilla/DebugOnly.h"
 
 #include "nsCOMPtr.h"
-#include "nsFrame.h"
 #include "nsFrameList.h"
 #include "nsPlaceholderFrame.h"
 #include "nsIContent.h"
diff --git a/layout/generic/nsFrameSetFrame.cpp b/layout/generic/nsFrameSetFrame.cpp
index 03b97ee4f68d..e777feaf8e9f 100644
--- a/layout/generic/nsFrameSetFrame.cpp
+++ b/layout/generic/nsFrameSetFrame.cpp
@@ -5,10 +5,11 @@
 
 /* rendering object for HTML <frameset> elements */
 
+#include "nsFrameSetFrame.h"
+
 #include "mozilla/DebugOnly.h"
 #include "mozilla/Likely.h"
 
-#include "nsFrameSetFrame.h"
 #include "nsGenericHTMLElement.h"
 #include "nsAttrValueInlines.h"
 #include "nsLeafFrame.h"
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index cb24b182247b..c658ac45fd72 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -5,13 +5,14 @@
 
 /* rendering object to wrap rendering objects that should be scrollable */
 
+#include "nsGfxScrollFrame.h"
+
 #include "base/compiler_specific.h"
 #include "nsCOMPtr.h"
 #include "nsPresContext.h"
 #include "nsView.h"
 #include "nsIScrollable.h"
 #include "nsContainerFrame.h"
-#include "nsGfxScrollFrame.h"
 #include "nsGkAtoms.h"
 #include "nsINameSpaceManager.h"
 #include "nsContentList.h"
diff --git a/layout/generic/nsHTMLCanvasFrame.cpp b/layout/generic/nsHTMLCanvasFrame.cpp
index d75fe3ea69ca..216c957c43c7 100644
--- a/layout/generic/nsHTMLCanvasFrame.cpp
+++ b/layout/generic/nsHTMLCanvasFrame.cpp
@@ -5,8 +5,9 @@
 
 /* rendering object for the HTML <canvas> element */
 
-#include "nsGkAtoms.h"
 #include "nsHTMLCanvasFrame.h"
+
+#include "nsGkAtoms.h"
 #include "mozilla/dom/HTMLCanvasElement.h"
 #include "nsDisplayList.h"
 #include "nsLayoutUtils.h"
diff --git a/layout/generic/nsHTMLReflowState.cpp b/layout/generic/nsHTMLReflowState.cpp
index fd1ff62c3248..4c08e96e9412 100644
--- a/layout/generic/nsHTMLReflowState.cpp
+++ b/layout/generic/nsHTMLReflowState.cpp
@@ -5,6 +5,8 @@
 
 /* struct containing the input to nsIFrame::Reflow */
 
+#include "nsHTMLReflowState.h"
+
 #include "nsStyleConsts.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsFrame.h"
diff --git a/layout/generic/nsImageFrame.cpp b/layout/generic/nsImageFrame.cpp
index d92bc9c2dd91..98fb094c0c30 100644
--- a/layout/generic/nsImageFrame.cpp
+++ b/layout/generic/nsImageFrame.cpp
@@ -5,10 +5,11 @@
 
 /* rendering object for replaced elements with bitmap image data */
 
+#include "nsImageFrame.h"
+
 #include "mozilla/DebugOnly.h"
 
 #include "nsCOMPtr.h"
-#include "nsImageFrame.h"
 #include "nsIImageLoadingContent.h"
 #include "nsString.h"
 #include "nsPrintfCString.h"
diff --git a/layout/generic/nsLineLayout.cpp b/layout/generic/nsLineLayout.cpp
index 8c650f066604..89787dc6b0f0 100644
--- a/layout/generic/nsLineLayout.cpp
+++ b/layout/generic/nsLineLayout.cpp
@@ -5,11 +5,12 @@
 
 /* state and methods used while laying out a single line of a block frame */
 
+// This has to be defined before nsLineLayout.h is included, because
+// nsLineLayout.h has a #include for plarena.h, which needs this defined:
 #define PL_ARENA_CONST_ALIGN_MASK (sizeof(void*)-1)
-#include "plarena.h"
+#include "nsLineLayout.h"
 
 #include "mozilla/Util.h"
-#include "nsLineLayout.h"
 #include "nsBlockFrame.h"
 #include "nsStyleConsts.h"
 #include "nsContainerFrame.h"
diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index 051a8a159210..3f0823ab9b6c 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -6,6 +6,8 @@
 
 /* rendering objects for replaced elements implemented by a plugin */
 
+#include "nsObjectFrame.h"
+
 #ifdef XP_WIN
 // This is needed for DoublePassRenderingEvent.
 #include "mozilla/plugins/PluginMessageUtils.h"
@@ -36,7 +38,6 @@
 #include "GeckoProfiler.h"
 #include <algorithm>
 
-#include "nsObjectFrame.h"
 #include "nsIObjectFrame.h"
 #include "nsPluginNativeWindow.h"
 #include "FrameLayerBuilder.h"
diff --git a/layout/generic/nsSimplePageSequence.cpp b/layout/generic/nsSimplePageSequence.cpp
index a954ba88ccd2..7296706999ac 100644
--- a/layout/generic/nsSimplePageSequence.cpp
+++ b/layout/generic/nsSimplePageSequence.cpp
@@ -2,8 +2,10 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-#include "nsCOMPtr.h"
+
 #include "nsSimplePageSequence.h"
+
+#include "nsCOMPtr.h"
 #include "nsPresContext.h"
 #include "gfxContext.h"
 #include "nsRenderingContext.h"
diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index bb2c36b17dc8..c7bc0c06a452 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -8,9 +8,10 @@
  * as <frame>, <iframe>, and some <object>s
  */
 
+#include "nsSubDocumentFrame.h"
+
 #include "mozilla/layout/RenderFrameParent.h"
 
-#include "nsSubDocumentFrame.h"
 #include "nsCOMPtr.h"
 #include "nsGenericHTMLElement.h"
 #include "nsAttrValueInlines.h"
diff --git a/layout/generic/nsVideoFrame.cpp b/layout/generic/nsVideoFrame.cpp
index defa6beca554..df192a6031d2 100644
--- a/layout/generic/nsVideoFrame.cpp
+++ b/layout/generic/nsVideoFrame.cpp
@@ -6,10 +6,11 @@
 
 /* rendering object for the HTML <video> element */
 
+#include "nsVideoFrame.h"
+
 #include "nsCOMPtr.h"
 #include "nsGkAtoms.h"
 
-#include "nsVideoFrame.h"
 #include "mozilla/dom/HTMLVideoElement.h"
 #include "nsIDOMHTMLVideoElement.h"
 #include "nsIDOMHTMLImageElement.h"