diff --git a/dom/smil/moz.build b/dom/smil/moz.build
index 5f999ae7e49..349ffed416e 100644
--- a/dom/smil/moz.build
+++ b/dom/smil/moz.build
@@ -67,6 +67,7 @@ FAIL_ON_WARNINGS = True
 LOCAL_INCLUDES += [
     '/dom/base',
     '/dom/svg',
+    '/layout/base',
     '/layout/style',
 ]
 
diff --git a/dom/smil/nsSMILAnimationController.cpp b/dom/smil/nsSMILAnimationController.cpp
index 50b44d16aa1..3c6f9486282 100644
--- a/dom/smil/nsSMILAnimationController.cpp
+++ b/dom/smil/nsSMILAnimationController.cpp
@@ -14,6 +14,7 @@
 #include "nsSMILTimedElement.h"
 #include <algorithm>
 #include "mozilla/AutoRestore.h"
+#include "RestyleTracker.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -814,6 +815,36 @@ nsSMILAnimationController::GetTargetIdentifierForAnimation(
   return true;
 }
 
+/*static*/ PLDHashOperator
+nsSMILAnimationController::AddStyleUpdate(AnimationElementPtrKey* aKey,
+                                          void* aData)
+{
+  SVGAnimationElement* animElement = aKey->GetKey();
+  RestyleTracker* restyleTracker = static_cast<RestyleTracker*>(aData);
+
+  nsSMILTargetIdentifier key;
+  if (!GetTargetIdentifierForAnimation(animElement, key)) {
+    // Something's wrong/missing about animation's target; skip this animation
+    return PL_DHASH_NEXT;
+  }
+
+  // mIsCSS true means that the rules are the ones returned from
+  // Element::GetSMILOverrideStyleRule (via nsSMILCSSProperty objects),
+  // and mIsCSS false means the rules are nsSMILMappedAttribute objects
+  // returned from nsSVGElement::GetAnimatedContentStyleRule.
+  nsRestyleHint rshint = key.mIsCSS ? eRestyle_StyleAttribute
+                                    : eRestyle_SVGAttrAnimations;
+  restyleTracker->AddPendingRestyle(key.mElement, rshint, nsChangeHint(0));
+
+  return PL_DHASH_NEXT;
+}
+
+void
+nsSMILAnimationController::AddStyleUpdatesTo(RestyleTracker& aTracker)
+{
+  mAnimationElementTable.EnumerateEntries(AddStyleUpdate, &aTracker);
+}
+
 //----------------------------------------------------------------------
 // Add/remove child time containers
 
diff --git a/dom/smil/nsSMILAnimationController.h b/dom/smil/nsSMILAnimationController.h
index 43f4063a698..9cff8a4fb7a 100644
--- a/dom/smil/nsSMILAnimationController.h
+++ b/dom/smil/nsSMILAnimationController.h
@@ -22,6 +22,7 @@ struct nsSMILTargetIdentifier;
 class nsIDocument;
 
 namespace mozilla {
+class RestyleTracker;
 namespace dom {
 class SVGAnimationElement;
 }
@@ -105,6 +106,8 @@ public:
   bool HasRegisteredAnimations()
   { return mAnimationElementTable.Count() != 0; }
 
+  void AddStyleUpdatesTo(mozilla::RestyleTracker& aTracker);
+
 protected:
   ~nsSMILAnimationController();
 
@@ -175,6 +178,9 @@ protected:
   static bool GetTargetIdentifierForAnimation(
       mozilla::dom::SVGAnimationElement* aAnimElem, nsSMILTargetIdentifier& aResult);
 
+  static PLDHashOperator
+    AddStyleUpdate(AnimationElementPtrKey* aKey, void* aData);
+
   // Methods for adding/removing time containers
   virtual nsresult AddChild(nsSMILTimeContainer& aChild) MOZ_OVERRIDE;
   virtual void     RemoveChild(nsSMILTimeContainer& aChild) MOZ_OVERRIDE;
diff --git a/layout/base/RestyleManager.cpp b/layout/base/RestyleManager.cpp
index ceac88a34c5..ec9665a707f 100644
--- a/layout/base/RestyleManager.cpp
+++ b/layout/base/RestyleManager.cpp
@@ -40,6 +40,7 @@
 #include "ActiveLayerTracker.h"
 #include "nsDisplayList.h"
 #include "RestyleTrackerInlines.h"
+#include "nsSMILAnimationController.h"
 
 #ifdef ACCESSIBILITY
 #include "nsAccessibilityService.h"
@@ -1744,10 +1745,25 @@ void
 RestyleManager::UpdateOnlyAnimationStyles()
 {
   TimeStamp now = mPresContext->RefreshDriver()->MostRecentRefresh();
-  if (mLastUpdateForThrottledAnimations == now) {
+  bool doCSS = mLastUpdateForThrottledAnimations != now;
+  mLastUpdateForThrottledAnimations = now;
+
+  bool doSMIL = false;
+  nsIDocument* document = mPresContext->Document();
+  nsSMILAnimationController* animationController = nullptr;
+  if (document->HasAnimationController()) {
+    animationController = document->GetAnimationController();
+    // FIXME:  Ideally, we only want to do this if animation timelines
+    // have advanced.  However, different SMIL animations could be
+    // getting their time from different outermost SVG elements, so
+    // finding all of them might be a pain.  So this could be optimized
+    // to set doSMIL to true in fewer cases.
+    doSMIL = true;
+  }
+
+  if (!doCSS && !doSMIL) {
     return;
   }
-  mLastUpdateForThrottledAnimations = now;
 
   nsTransitionManager* transitionManager = mPresContext->TransitionManager();
   nsAnimationManager* animationManager = mPresContext->AnimationManager();
@@ -1758,12 +1774,18 @@ RestyleManager::UpdateOnlyAnimationStyles()
                          ELEMENT_IS_POTENTIAL_ANIMATION_ONLY_RESTYLE_ROOT);
   tracker.Init(this);
 
-  // FIXME:  We should have the transition manager and animation manager
-  // add only the elements for which animations are currently throttled
-  // (i.e., animating on the compositor with main-thread style updates
-  // suppressed).
-  transitionManager->AddStyleUpdatesTo(tracker);
-  animationManager->AddStyleUpdatesTo(tracker);
+  if (doCSS) {
+    // FIXME:  We should have the transition manager and animation manager
+    // add only the elements for which animations are currently throttled
+    // (i.e., animating on the compositor with main-thread style updates
+    // suppressed).
+    transitionManager->AddStyleUpdatesTo(tracker);
+    animationManager->AddStyleUpdatesTo(tracker);
+  }
+
+  if (doSMIL) {
+    animationController->AddStyleUpdatesTo(tracker);
+  }
 
   ProcessRestyles(tracker);