diff -u a/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.h b/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.h
--- a/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.h	2015-05-29 22:30:38.000000000 +0200
+++ b/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.h	2015-08-06 19:13:13.000000000 +0200
@@ -58,7 +58,6 @@

 private:
     QImage m_qImage;
-    CGImageRef m_cgImage;
     QSize m_requestedSize;
 };
 
diff -u a/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.mm b/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.mm
--- a/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.mm	2015-05-29 22:30:38.000000000 +0200
+++ b/qtbase/src/plugins/platforms/cocoa/qcocoabackingstore.mm	2015-08-06 19:51:48.000000000 +0200
@@ -47,14 +47,13 @@

 QCocoaBackingStore::QCocoaBackingStore(QWindow *window)
     : QPlatformBackingStore(window)
-    , m_cgImage(0)
 {
 }

 QCocoaBackingStore::~QCocoaBackingStore()
 {
-    CGImageRelease(m_cgImage);
-    m_cgImage = 0;
+    if (QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(window()->handle()))
+        [cocoaWindow->m_qtView clearBackingStore:this];
 }

 QPaintDevice *QCocoaBackingStore::paintDevice()
@@ -66,9 +65,6 @@
     // either due to a window resize or devicePixelRatio change.
     QSize effectiveBufferSize = m_requestedSize * windowDevicePixelRatio;
     if (m_qImage.size() != effectiveBufferSize) {
-        CGImageRelease(m_cgImage);
-        m_cgImage = 0;
-
         QImage::Format format = (window()->format().hasAlpha() || cocoaWindow->m_drawContentBorderGradient)
                 ? QImage::Format_ARGB32_Premultiplied : QImage::Format_RGB32;
         m_qImage = QImage(effectiveBufferSize, format);
@@ -81,15 +77,6 @@

 void QCocoaBackingStore::flush(QWindow *win, const QRegion &region, const QPoint &offset)
 {
-    // A flush means that qImage has changed. Since CGImages are seen as
-    // immutable, CoreImage fails to pick up this change for m_cgImage
-    // (since it usually cached), so we must recreate it. We await doing this
-    // until one of the views needs it, since, together with calling
-    // "setNeedsDisplayInRect" instead of "displayRect" we will, in most
-    // cases, get away with doing this once for every repaint. Also note that
-    // m_cgImage is only a reference to the data inside m_qImage, it is not a copy.
-    CGImageRelease(m_cgImage);
-    m_cgImage = 0;
     if (!m_qImage.isNull()) {
         if (QCocoaWindow *cocoaWindow = static_cast<QCocoaWindow *>(win->handle()))
             [cocoaWindow->m_qtView flushBackingStore:this region:region offset:offset];
diff -r -u a/qtbase/src/plugins/platforms/cocoa/qnsview.h b/qtbase/src/plugins/platforms/cocoa/qnsview.h
--- a/qtbase/src/plugins/platforms/cocoa/qnsview.h	2015-05-29 22:30:38.000000000 +0200
+++ b/qtbase/src/plugins/platforms/cocoa/qnsview.h	2015-08-06 19:50:54.000000000 +0200
@@ -51,8 +51,7 @@
 Q_FORWARD_DECLARE_OBJC_CLASS(QT_MANGLE_NAMESPACE(QNSViewMouseMoveHelper));

 @interface QT_MANGLE_NAMESPACE(QNSView) : NSView <NSTextInputClient> {
-    QImage m_backingStore;
-    qreal m_pixelRatio;
+    QCocoaBackingStore* m_backingStore;
     QPoint m_backingStoreOffset;
     CGImageRef m_maskImage;
     uchar *m_maskData;
@@ -82,6 +81,7 @@
 - (void)setQCocoaGLContext:(QCocoaGLContext *)context;
 #endif
 - (void)flushBackingStore:(QCocoaBackingStore *)backingStore region:(const QRegion &)region offset:(QPoint)offset;
+- (void)clearBackingStore:(QCocoaBackingStore *)backingStore;
 - (void)setMaskRegion:(const QRegion *)region;
 - (void)invalidateWindowShadowIfNeeded;
 - (void)drawRect:(NSRect)dirtyRect;
diff -r -u a/qtbase/src/plugins/platforms/cocoa/qnsview.mm b/qtbase/src/plugins/platforms/cocoa/qnsview.mm
--- a/qtbase/src/plugins/platforms/cocoa/qnsview.mm	2015-05-29 22:30:38.000000000 +0200
+++ b/qtbase/src/plugins/platforms/cocoa/qnsview.mm	2015-08-07 17:12:12.000000000 +0200
@@ -143,7 +143,7 @@
 {
     self = [super initWithFrame : NSMakeRect(0,0, 300,300)];
     if (self) {
-        m_pixelRatio = 1.;
+        m_backingStore = 0;
         m_maskImage = 0;
         m_shouldInvalidateWindowShadow = false;
         m_window = 0;
@@ -367,7 +367,7 @@
         if (!m_platformWindow->m_inSetGeometry)
             QWindowSystemInterface::flushWindowSystemEvents();
         else
-            m_backingStore = QImage();
+            m_backingStore = 0;
     }
 }

@@ -472,14 +472,20 @@

 - (void) flushBackingStore:(QCocoaBackingStore *)backingStore region:(const QRegion &)region offset:(QPoint)offset
 {
-    m_backingStore = backingStore->toImage();
-    m_pixelRatio = backingStore->getBackingStoreDevicePixelRatio();
-    m_backingStoreOffset = offset * m_pixelRatio;
+    m_backingStore = backingStore;
+    m_backingStoreOffset = offset * m_backingStore->getBackingStoreDevicePixelRatio();
     foreach (QRect rect, region.rects()) {
         [self setNeedsDisplayInRect:NSMakeRect(rect.x(), rect.y(), rect.width(), rect.height())];
     }
 }

+- (void)clearBackingStore:(QCocoaBackingStore *)backingStore
+{
+    if (backingStore == m_backingStore) {
+        m_backingStore = 0;
+    }
+}
+
 - (BOOL) hasMask
 {
     return m_maskImage != 0;
@@ -538,7 +544,7 @@
     if (m_platformWindow->m_drawContentBorderGradient)
         NSDrawWindowBackground(dirtyRect);

-    if (m_backingStore.isNull())
+    if (!m_backingStore)
         return;

     // Calculate source and target rects. The target rect is the dirtyRect:
@@ -546,10 +552,11 @@

     // The backing store source rect will be larger on retina displays.
     // Scale dirtyRect by the device pixel ratio:
-    CGRect dirtyBackingRect = CGRectMake(dirtyRect.origin.x * m_pixelRatio,
-                                         dirtyRect.origin.y * m_pixelRatio,
-                                         dirtyRect.size.width * m_pixelRatio,
-                                         dirtyRect.size.height * m_pixelRatio);
+    const qreal devicePixelRatio = m_backingStore->getBackingStoreDevicePixelRatio();
+    CGRect dirtyBackingRect = CGRectMake(dirtyRect.origin.x * devicePixelRatio,
+                                         dirtyRect.origin.y * devicePixelRatio,
+                                         dirtyRect.size.width * devicePixelRatio,
+                                         dirtyRect.size.height * devicePixelRatio);

     NSGraphicsContext *nsGraphicsContext = [NSGraphicsContext currentContext];
     CGContextRef cgContext = (CGContextRef) [nsGraphicsContext graphicsPort];
@@ -575,7 +582,7 @@
         dirtyBackingRect.size.width,
         dirtyBackingRect.size.height
     );
-    CGImageRef bsCGImage = qt_mac_toCGImage(m_backingStore);
+    CGImageRef bsCGImage = qt_mac_toCGImage(m_backingStore->toImage());
     CGImageRef cleanImg = CGImageCreateWithImageInRect(bsCGImage, backingStoreRect);

     // Optimization: Copy frame buffer content instead of blending for