--- a/gfx/thebes/gfxPrefs.h
+++ b/gfx/thebes/gfxPrefs.h
@@ -535,18 +535,20 @@ private:
   DECL_GFX_PREF(Once, "layers.tiles.adjust",                   LayersTilesAdjust, bool, true);
   DECL_GFX_PREF(Once, "layers.tiles.edge-padding",             TileEdgePaddingEnabled, bool, true);
   DECL_GFX_PREF(Live, "layers.tiles.fade-in.enabled",          LayerTileFadeInEnabled, bool, false);
   DECL_GFX_PREF(Live, "layers.tiles.fade-in.duration-ms",      LayerTileFadeInDuration, uint32_t, 250);
   DECL_GFX_PREF(Live, "layers.transaction.warning-ms",         LayerTransactionWarning, uint32_t, 200);
   DECL_GFX_PREF(Once, "layers.uniformity-info",                UniformityInfo, bool, false);
   DECL_GFX_PREF(Once, "layers.use-image-offscreen-surfaces",   UseImageOffscreenSurfaces, bool, true);
   DECL_GFX_PREF(Live, "layers.draw-mask-debug",                DrawMaskLayer, bool, false);
+
   DECL_GFX_PREF(Live, "layers.geometry.opengl.enabled",        OGLLayerGeometry, bool, false);
   DECL_GFX_PREF(Live, "layers.geometry.basic.enabled",         BasicLayerGeometry, bool, false);
+  DECL_GFX_PREF(Live, "layers.geometry.d3d11.enabled",         D3D11LayerGeometry, bool, false);
 
   DECL_GFX_PREF(Live, "layout.animation.prerender.partial", PartiallyPrerenderAnimatedContent, bool, false);
   DECL_GFX_PREF(Live, "layout.animation.prerender.viewport-ratio-limit-x", AnimationPrerenderViewportRatioLimitX, float, 1.125f);
   DECL_GFX_PREF(Live, "layout.animation.prerender.viewport-ratio-limit-y", AnimationPrerenderViewportRatioLimitY, float, 1.125f);
   DECL_GFX_PREF(Live, "layout.animation.prerender.absolute-limit-x", AnimationPrerenderAbsoluteLimitX, uint32_t, 4096);
   DECL_GFX_PREF(Live, "layout.animation.prerender.absolute-limit-y", AnimationPrerenderAbsoluteLimitY, uint32_t, 4096);
 
   DECL_GFX_PREF(Live, "layout.css.scroll-behavior.damping-ratio", ScrollBehaviorDampingRatio, float, 1.0f);

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -618,16 +618,19 @@ pref("layers.async-pan-zoom.enabled", tr
 pref("layout.event-regions.enabled", false);
 
 // Whether to enable arbitrary layer geometry for OpenGL compositor
 pref("layers.geometry.opengl.enabled", true);
 
 // Whether to enable arbitrary layer geometry for Basic compositor
 pref("layers.geometry.basic.enabled", true);
 
+// Whether to enable arbitrary layer geometry for DirectX compositor
+pref("layers.geometry.d3d11.enabled", true);
+
 // APZ preferences. For documentation/details on what these prefs do, check
 // gfx/layers/apz/src/AsyncPanZoomController.cpp.
 pref("apz.allow_checkerboarding", true);
 pref("apz.allow_immediate_handoff", true);
 pref("apz.allow_with_webrender", false);
 pref("apz.allow_zooming", false);
 
 // Whether to lock touch scrolling to one axis at a time