--- a/devtools/client/locales/en-US/markers.properties
+++ b/devtools/client/locales/en-US/markers.properties
@@ -10,16 +10,17 @@
 # A good criteria is the language in which you'd find the best
 # documentation on web development on the web. These strings
 # are specifically for marker names in the performance tool.
 
 # LOCALIZATION NOTE (marker.label.*):
 # These strings are displayed in the Performance Tool waterfall, identifying markers.
 # We want to use the same wording as Google Chrome when appropriate.
 marker.label.styles=Recalculate Style
+marker.label.stylesApplyChanges=Apply Style Changes
 marker.label.reflow=Layout
 marker.label.paint=Paint
 marker.label.composite=Composite Layers
 marker.label.compositeForwardTransaction=Composite Request Sent
 marker.label.javascript=Function Call
 marker.label.parseHTML=Parse HTML
 marker.label.parseXML=Parse XML
 marker.label.domevent=DOM Event

--- a/devtools/client/performance/modules/markers.js
+++ b/devtools/client/performance/modules/markers.js
@@ -48,16 +48,21 @@ const TIMELINE_BLUEPRINT = {
   /* Group 0 - Reflow and Rendering pipeline */
 
   "Styles": {
     group: 0,
     colorName: "graphs-purple",
     label: L10N.getStr("marker.label.styles"),
     fields: Formatters.StylesFields,
   },
+  "StylesApplyChanges": {
+    group: 0,
+    colorName: "graphs-purple",
+    label: L10N.getStr("marker.label.stylesApplyChanges"),
+  },
   "Reflow": {
     group: 0,
     colorName: "graphs-purple",
     label: L10N.getStr("marker.label.reflow"),
   },
   "Paint": {
     group: 0,
     colorName: "graphs-green",

--- a/layout/base/ServoRestyleManager.cpp
+++ b/layout/base/ServoRestyleManager.cpp
@@ -1,16 +1,18 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/ServoRestyleManager.h"
 
+#include "mozilla/AutoRestyleTimelineMarker.h"
+#include "mozilla/AutoTimelineMarker.h"
 #include "mozilla/DocumentStyleRootIterator.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/ServoStyleSet.h"
 #include "mozilla/Unused.h"
 #include "mozilla/ViewportFrame.h"
 #include "mozilla/dom/ChildIterator.h"
 #include "mozilla/dom/ElementInlines.h"
 #include "nsBlockFrame.h"
@@ -763,52 +765,60 @@ ServoRestyleManager::DoProcessPendingRes
     ? TraversalRestyleBehavior::ForCSSRuleChanges
     : TraversalRestyleBehavior::Normal;
   while (animationOnly ? styleSet->StyleDocumentForAnimationOnly()
                        : styleSet->StyleDocument(restyleBehavior)) {
     if (!animationOnly) {
       ClearSnapshots();
     }
 
+    nsStyleChangeList currentChanges(StyleBackendType::Servo);
+    bool anyStyleChanged = false;
+
     // Recreate style contexts, and queue up change hints (which also handle
     // lazy frame construction).
-    nsStyleChangeList currentChanges(StyleBackendType::Servo);
-    DocumentStyleRootIterator iter(doc);
-    bool anyStyleChanged = false;
-    while (Element* root = iter.GetNextStyleRoot()) {
-      ServoRestyleState state(*styleSet, currentChanges);
-      anyStyleChanged |= ProcessPostTraversal(root, nullptr, state);
+    {
+      AutoRestyleTimelineMarker marker(
+        mPresContext->GetDocShell(), animationOnly);
+      DocumentStyleRootIterator iter(doc);
+      while (Element* root = iter.GetNextStyleRoot()) {
+        ServoRestyleState state(*styleSet, currentChanges);
+        anyStyleChanged |= ProcessPostTraversal(root, nullptr, state);
+      }
     }
 
     // Process the change hints.
     //
     // Unfortunately, the frame constructor can generate new change hints while
     // processing existing ones. We redirect those into a secondary queue and
     // iterate until there's nothing left.
-    ReentrantChangeList newChanges;
-    mReentrantChanges = &newChanges;
-    while (!currentChanges.IsEmpty()) {
-      ProcessRestyledFrames(currentChanges);
-      MOZ_ASSERT(currentChanges.IsEmpty());
-      for (ReentrantChange& change: newChanges)  {
-        if (!(change.mHint & nsChangeHint_ReconstructFrame) &&
-            !change.mContent->GetPrimaryFrame()) {
-          // SVG Elements post change hints without ensuring that the primary
-          // frame will be there after that (see bug 1366142).
-          //
-          // Just ignore those, since we can't really process them.
-          continue;
+    {
+      AutoTimelineMarker marker(
+        mPresContext->GetDocShell(), "StylesApplyChanges");
+      ReentrantChangeList newChanges;
+      mReentrantChanges = &newChanges;
+      while (!currentChanges.IsEmpty()) {
+        ProcessRestyledFrames(currentChanges);
+        MOZ_ASSERT(currentChanges.IsEmpty());
+        for (ReentrantChange& change: newChanges)  {
+          if (!(change.mHint & nsChangeHint_ReconstructFrame) &&
+              !change.mContent->GetPrimaryFrame()) {
+            // SVG Elements post change hints without ensuring that the primary
+            // frame will be there after that (see bug 1366142).
+            //
+            // Just ignore those, since we can't really process them.
+            continue;
+          }
+          currentChanges.AppendChange(change.mContent->GetPrimaryFrame(),
+                                      change.mContent, change.mHint);
         }
-        currentChanges.AppendChange(change.mContent->GetPrimaryFrame(),
-                                    change.mContent, change.mHint);
+        newChanges.Clear();
       }
-      newChanges.Clear();
+      mReentrantChanges = nullptr;
     }
-    mReentrantChanges = nullptr;
-
 
     if (anyStyleChanged) {
       // Maybe no styles changed when:
       //
       //  * Only explicit change hints were posted in the first place.
       //  * When an attribute or state change in the content happens not to need
       //    a restyle after all.
       //

--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -2,16 +2,17 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "mozilla/ServoStyleSet.h"
 
 #include "gfxPlatformFontList.h"
+#include "mozilla/AutoRestyleTimelineMarker.h"
 #include "mozilla/DocumentStyleRootIterator.h"
 #include "mozilla/ServoBindings.h"
 #include "mozilla/ServoRestyleManager.h"
 #include "mozilla/ServoStyleRuleMap.h"
 #include "mozilla/css/Loader.h"
 #include "mozilla/dom/AnonymousContent.h"
 #include "mozilla/dom/ChildIterator.h"
 #include "mozilla/dom/Element.h"
@@ -418,31 +419,35 @@ ServoStyleSet::PreTraverse(Element* aRoo
 }
 
 bool
 ServoStyleSet::PrepareAndTraverseSubtree(
   RawGeckoElementBorrowed aRoot,
   TraversalRootBehavior aRootBehavior,
   TraversalRestyleBehavior aRestyleBehavior)
 {
+  bool forAnimationOnly =
+    aRestyleBehavior == TraversalRestyleBehavior::ForAnimationOnly;
+
+  AutoRestyleTimelineMarker marker(
+    mPresContext->GetDocShell(), forAnimationOnly);
+
   // Get the Document's root element to ensure that the cache is valid before
   // calling into the (potentially-parallel) Servo traversal, where a cache hit
   // is necessary to avoid a data race when updating the cache.
   mozilla::Unused << aRoot->OwnerDoc()->GetRootElement();
 
   MOZ_ASSERT(!StylistNeedsUpdate());
   AutoSetInServoTraversal guard(this);
 
   const SnapshotTable& snapshots = Snapshots();
 
   bool isInitial = !aRoot->HasServoData();
   bool forReconstruct =
     aRestyleBehavior == TraversalRestyleBehavior::ForReconstruct;
-  bool forAnimationOnly =
-    aRestyleBehavior == TraversalRestyleBehavior::ForAnimationOnly;
 #ifdef DEBUG
   bool forNewlyBoundElement =
     aRestyleBehavior == TraversalRestyleBehavior::ForNewlyBoundElement;
 #endif
   bool postTraversalRequired = Servo_TraverseSubtree(
     aRoot, mRawSet.get(), &snapshots, aRootBehavior, aRestyleBehavior);
   MOZ_ASSERT(!(isInitial || forReconstruct || forNewlyBoundElement) ||
              !postTraversalRequired);