diff --git a/gfx/cairo/README b/gfx/cairo/README
index 1007e073969..ba2f7732f07 100644
--- a/gfx/cairo/README
+++ b/gfx/cairo/README
@@ -150,6 +150,8 @@ quartz-mask-non-OVER.patch: Don't use CGContextSetAlpha to optimize alpha maskin
 
 quartz-layers-content.patch: Store cairo content type in CGLayer surfaces
 
+quartz-optimize-OVER.patch: Optimize OVER to SOURCE for opaque patterns
+
 ==== pixman patches ====
 
 pixman-android-cpu-detect.patch: Add CPU detection support for Android, where we can't reliably access /proc/self/auxv.
diff --git a/gfx/cairo/cairo/src/cairo-quartz-surface.c b/gfx/cairo/cairo/src/cairo-quartz-surface.c
index 399e48a320a..c64cd2c0bf1 100644
--- a/gfx/cairo/cairo/src/cairo-quartz-surface.c
+++ b/gfx/cairo/cairo/src/cairo-quartz-surface.c
@@ -127,6 +127,7 @@ static bool (*CGContextGetShouldSmoothFontsPtr) (CGContextRef) = NULL;
 static void (*CGContextSetAllowsFontSmoothingPtr) (CGContextRef, bool) = NULL;
 static bool (*CGContextGetAllowsFontSmoothingPtr) (CGContextRef) = NULL;
 static void (*CGContextReplacePathWithClipPathPtr) (CGContextRef) = NULL;
+static CGFloat (*CGContextGetAlphaPtr) (CGContextRef) = NULL;
 
 static SInt32 _cairo_quartz_osx_version = 0x0;
 
@@ -162,6 +163,7 @@ static void quartz_ensure_symbols(void)
     CGContextReplacePathWithClipPathPtr = dlsym(RTLD_DEFAULT, "CGContextReplacePathWithClipPath");
     CGContextGetAllowsFontSmoothingPtr = dlsym(RTLD_DEFAULT, "CGContextGetAllowsFontSmoothing");
     CGContextSetAllowsFontSmoothingPtr = dlsym(RTLD_DEFAULT, "CGContextSetAllowsFontSmoothing");
+    CGContextGetAlphaPtr = dlsym(RTLD_DEFAULT, "CGContextGetAlpha");
 
     if (Gestalt(gestaltSystemVersion, &_cairo_quartz_osx_version) != noErr) {
 	// assume 10.4
@@ -1703,6 +1705,18 @@ _cairo_quartz_setup_state (cairo_quartz_surface_t *surface,
     }
 
     if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
+        if (op == CAIRO_OPERATOR_OVER && _cairo_pattern_is_opaque (source) &&
+            CGContextGetAlphaPtr &&
+            CGContextGetAlphaPtr (surface->cgContext) == 1.0) {
+            // Quartz won't touch pixels outside the bounds of the
+            // source surface, so we can just go ahead and use Copy here
+            // to accelerate things.
+            // Quartz won't necessarily be able to do this optimization internally;
+            // for CGLayer surfaces, we can know all the pixels are opaque
+            // (because it's CONTENT_COLOR), but Quartz won't know.
+            CGContextSetCompositeOperation (context, kPrivateCGCompositeCopy);
+        }
+
 	const cairo_surface_pattern_t *spat = (const cairo_surface_pattern_t *) source;
         _cairo_quartz_setup_surface_source (surface, spat, extents, &state);
         return state;
diff --git a/gfx/cairo/quartz-optimize-OVER.patch b/gfx/cairo/quartz-optimize-OVER.patch
new file mode 100644
index 00000000000..2c587459b45
--- /dev/null
+++ b/gfx/cairo/quartz-optimize-OVER.patch
@@ -0,0 +1,71 @@
+From: Robert O'Callahan <robert@ocallahan.org>
+Bug 579885. Part 4: Paint opaque surfaces using kPrivateCGCompositeCopy when possible. r=jrmuizel,a=blocking
+
+diff --git a/gfx/cairo/cairo/src/cairo-quartz-surface.c b/gfx/cairo/cairo/src/cairo-quartz-surface.c
+--- a/gfx/cairo/cairo/src/cairo-quartz-surface.c
++++ b/gfx/cairo/cairo/src/cairo-quartz-surface.c
+@@ -122,16 +122,17 @@ static void (*CGContextClipToMaskPtr) (C
+ static void (*CGContextDrawTiledImagePtr) (CGContextRef, CGRect, CGImageRef) = NULL;
+ static unsigned int (*CGContextGetTypePtr) (CGContextRef) = NULL;
+ static void (*CGContextSetShouldAntialiasFontsPtr) (CGContextRef, bool) = NULL;
+ static bool (*CGContextGetShouldAntialiasFontsPtr) (CGContextRef) = NULL;
+ static bool (*CGContextGetShouldSmoothFontsPtr) (CGContextRef) = NULL;
+ static void (*CGContextSetAllowsFontSmoothingPtr) (CGContextRef, bool) = NULL;
+ static bool (*CGContextGetAllowsFontSmoothingPtr) (CGContextRef) = NULL;
+ static void (*CGContextReplacePathWithClipPathPtr) (CGContextRef) = NULL;
++static CGFloat (*CGContextGetAlphaPtr) (CGContextRef) = NULL;
+ 
+ static SInt32 _cairo_quartz_osx_version = 0x0;
+ 
+ static cairo_bool_t _cairo_quartz_symbol_lookup_done = FALSE;
+ 
+ /*
+  * Utility functions
+  */
+@@ -157,16 +158,17 @@ static void quartz_ensure_symbols(void)
+     CGContextDrawTiledImagePtr = dlsym(RTLD_DEFAULT, "CGContextDrawTiledImage");
+     CGContextGetTypePtr = dlsym(RTLD_DEFAULT, "CGContextGetType");
+     CGContextSetShouldAntialiasFontsPtr = dlsym(RTLD_DEFAULT, "CGContextSetShouldAntialiasFonts");
+     CGContextGetShouldAntialiasFontsPtr = dlsym(RTLD_DEFAULT, "CGContextGetShouldAntialiasFonts");
+     CGContextGetShouldSmoothFontsPtr = dlsym(RTLD_DEFAULT, "CGContextGetShouldSmoothFonts");
+     CGContextReplacePathWithClipPathPtr = dlsym(RTLD_DEFAULT, "CGContextReplacePathWithClipPath");
+     CGContextGetAllowsFontSmoothingPtr = dlsym(RTLD_DEFAULT, "CGContextGetAllowsFontSmoothing");
+     CGContextSetAllowsFontSmoothingPtr = dlsym(RTLD_DEFAULT, "CGContextSetAllowsFontSmoothing");
++    CGContextGetAlphaPtr = dlsym(RTLD_DEFAULT, "CGContextGetAlpha");
+ 
+     if (Gestalt(gestaltSystemVersion, &_cairo_quartz_osx_version) != noErr) {
+ 	// assume 10.4
+ 	_cairo_quartz_osx_version = 0x1040;
+     }
+ 
+     _cairo_quartz_symbol_lookup_done = TRUE;
+ }
+@@ -1698,16 +1700,28 @@ _cairo_quartz_setup_state (cairo_quartz_
+ 
+     if (source->type == CAIRO_PATTERN_TYPE_RADIAL) {
+ 	const cairo_radial_pattern_t *rpat = (const cairo_radial_pattern_t *)source;
+ 	_cairo_quartz_setup_radial_source (surface, rpat, extents, &state);
+ 	return state;
+     }
+ 
+     if (source->type == CAIRO_PATTERN_TYPE_SURFACE) {
++        if (op == CAIRO_OPERATOR_OVER && _cairo_pattern_is_opaque (source) &&
++            CGContextGetAlphaPtr &&
++            CGContextGetAlphaPtr (surface->cgContext) == 1.0) {
++            // Quartz won't touch pixels outside the bounds of the
++            // source surface, so we can just go ahead and use Copy here
++            // to accelerate things.
++            // Quartz won't necessarily be able to do this optimization internally;
++            // for CGLayer surfaces, we can know all the pixels are opaque
++            // (because it's CONTENT_COLOR), but Quartz won't know.
++            CGContextSetCompositeOperation (context, kPrivateCGCompositeCopy);
++        }
++
+ 	const cairo_surface_pattern_t *spat = (const cairo_surface_pattern_t *) source;
+         _cairo_quartz_setup_surface_source (surface, spat, extents, &state);
+         return state;
+     }
+ 
+     state.action = DO_UNSUPPORTED;
+     return state;
+ }