diff --git a/gfx/gl/GLContext.h b/gfx/gl/GLContext.h
index 31b9e64a892c..4f12477d35e8 100644
--- a/gfx/gl/GLContext.h
+++ b/gfx/gl/GLContext.h
@@ -1037,8 +1037,16 @@ public:
         }
 
         BeforeGLReadCall();
-        raw_fCopyTexImage2D(target, level, internalformat,
-                            x, y, width, height, border);
+        bool didCopyTexImage2D = false;
+        if (mScreen) {
+            didCopyTexImage2D = mScreen->CopyTexImage2D(target, level, internalformat, x,
+                                                        y, width, height, border);
+        }
+
+        if (!didCopyTexImage2D) {
+            raw_fCopyTexImage2D(target, level, internalformat, x, y, width, height,
+                                border);
+        }
         AfterGLReadCall();
     }
 
@@ -1932,6 +1940,9 @@ public:
     }
 
 private:
+
+    friend class SharedSurface_IOSurface;
+
     void raw_fCopyTexImage2D(GLenum target, GLint level, GLenum internalformat, GLint x, GLint y, GLsizei width, GLsizei height, GLint border)
     {
         BEFORE_GL_CALL;
diff --git a/gfx/gl/GLScreenBuffer.cpp b/gfx/gl/GLScreenBuffer.cpp
index 51145adc51d8..9abdd76052fb 100755
--- a/gfx/gl/GLScreenBuffer.cpp
+++ b/gfx/gl/GLScreenBuffer.cpp
@@ -313,6 +313,23 @@ GLScreenBuffer::BeforeReadCall()
     AssureBlitted();
 }
 
+bool
+GLScreenBuffer::CopyTexImage2D(GLenum target, GLint level, GLenum internalformat, GLint x,
+                               GLint y, GLsizei width, GLsizei height, GLint border)
+{
+    SharedSurface* surf;
+    if (GetReadFB() == 0) {
+        surf = SharedSurf();
+    } else {
+        surf = mGL->mFBOMapping[GetReadFB()];
+    }
+    if (surf) {
+        return surf->CopyTexImage2D(target, level, internalformat,  x, y, width, height, border);
+    }
+
+    return false;
+}
+
 bool
 GLScreenBuffer::ReadPixels(GLint x, GLint y,
                            GLsizei width, GLsizei height,
diff --git a/gfx/gl/GLScreenBuffer.h b/gfx/gl/GLScreenBuffer.h
index 89c6eae2c37f..965f068455a6 100644
--- a/gfx/gl/GLScreenBuffer.h
+++ b/gfx/gl/GLScreenBuffer.h
@@ -228,6 +228,9 @@ public:
     void AfterDrawCall();
     void BeforeReadCall();
 
+    bool CopyTexImage2D(GLenum target, GLint level, GLenum internalformat, GLint x,
+                        GLint y, GLsizei width, GLsizei height, GLint border);
+
     void SetReadBuffer(GLenum userMode);
 
     /**
diff --git a/gfx/gl/SharedSurface.h b/gfx/gl/SharedSurface.h
index 0f011c8030d0..094f61b5af1a 100644
--- a/gfx/gl/SharedSurface.h
+++ b/gfx/gl/SharedSurface.h
@@ -156,6 +156,12 @@ public:
         MOZ_CRASH("Did you forget to override this function?");
     }
 
+    virtual bool CopyTexImage2D(GLenum target, GLint level, GLenum internalformat, GLint x,
+                                GLint y, GLsizei width, GLsizei height, GLint border)
+    {
+        return false;
+    }
+
     virtual bool ReadPixels(GLint x, GLint y,
                             GLsizei width, GLsizei height,
                             GLenum format, GLenum type,
diff --git a/gfx/gl/SharedSurfaceIO.cpp b/gfx/gl/SharedSurfaceIO.cpp
index de4de735c5da..d9ec0acc6995 100644
--- a/gfx/gl/SharedSurfaceIO.cpp
+++ b/gfx/gl/SharedSurfaceIO.cpp
@@ -35,6 +35,49 @@ SharedSurface_IOSurface::Fence()
     mGL->fFlush();
 }
 
+bool
+SharedSurface_IOSurface::CopyTexImage2D(GLenum target, GLint level, GLenum internalformat,
+                                        GLint x, GLint y, GLsizei width, GLsizei height,
+                                        GLint border)
+{
+    /* Bug 896693 - OpenGL framebuffers that are backed by IOSurface on OSX expose a bug
+     * in glCopyTexImage2D --- internalformats GL_ALPHA, GL_LUMINANCE, GL_LUMINANCE_ALPHA
+     * return the wrong results. To work around, copy framebuffer to a temporary texture
+     * using GL_RGBA (which works), attach as read framebuffer and glCopyTexImage2D
+     * instead.
+     */
+
+    // https://www.opengl.org/sdk/docs/man3/xhtml/glCopyTexImage2D.xml says that width or
+    // height set to 0 results in a NULL texture. Lets not do any work and punt to
+    // original glCopyTexImage2D, since the FBO below will fail when trying to attach a
+    // texture of 0 width or height.
+    if (width == 0 || height == 0)
+        return false;
+
+    MOZ_ASSERT(mGL->IsCurrent());
+
+    ScopedTexture destTex(mGL);
+    {
+        ScopedBindTexture bindTex(mGL, destTex.Texture());
+        mGL->fTexParameteri(LOCAL_GL_TEXTURE_2D, LOCAL_GL_TEXTURE_MIN_FILTER,
+                            LOCAL_GL_NEAREST);
+        mGL->fTexParameteri(LOCAL_GL_TEXTURE_2D, LOCAL_GL_TEXTURE_MAG_FILTER,
+                            LOCAL_GL_NEAREST);
+        mGL->fTexParameteri(LOCAL_GL_TEXTURE_2D, LOCAL_GL_TEXTURE_WRAP_S,
+                            LOCAL_GL_CLAMP_TO_EDGE);
+        mGL->fTexParameteri(LOCAL_GL_TEXTURE_2D, LOCAL_GL_TEXTURE_WRAP_T,
+                            LOCAL_GL_CLAMP_TO_EDGE);
+        mGL->raw_fCopyTexImage2D(LOCAL_GL_TEXTURE_2D, 0, LOCAL_GL_RGBA, x, y, width,
+                                 height, 0);
+    }
+
+    ScopedFramebufferForTexture tmpFB(mGL, destTex.Texture(), LOCAL_GL_TEXTURE_2D);
+    ScopedBindFramebuffer bindFB(mGL, tmpFB.FB());
+    mGL->raw_fCopyTexImage2D(target, level, internalformat, x, y, width, height, border);
+
+    return true;
+}
+
 bool
 SharedSurface_IOSurface::ReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
                                     GLenum format, GLenum type, GLvoid* pixels)
diff --git a/gfx/gl/SharedSurfaceIO.h b/gfx/gl/SharedSurfaceIO.h
index 1ce485cbe52e..d1a3724ebd81 100644
--- a/gfx/gl/SharedSurfaceIO.h
+++ b/gfx/gl/SharedSurfaceIO.h
@@ -30,6 +30,9 @@ public:
     virtual bool WaitSync() override { return true; }
     virtual bool PollSync() override { return true; }
 
+    virtual bool CopyTexImage2D(GLenum target, GLint level, GLenum internalformat,
+                                GLint x, GLint y, GLsizei width, GLsizei height,
+                                GLint border) override;
     virtual bool ReadPixels(GLint x, GLint y, GLsizei width, GLsizei height,
                             GLenum format, GLenum type, GLvoid *pixels) override;