diff --git a/browser/devtools/performance/modules/markers.js b/browser/devtools/performance/modules/markers.js
index 374f70d9567..e48a0c25419 100644
--- a/browser/devtools/performance/modules/markers.js
+++ b/browser/devtools/performance/modules/markers.js
@@ -73,6 +73,11 @@ const TIMELINE_BLUEPRINT = {
     colorName: "graphs-green",
     label: L10N.getStr("marker.label.paint"),
   },
+  "Composite": {
+    group: 0,
+    colorName: "graphs-green",
+    label: L10N.getStr("marker.label.composite"),
+  },
 
   /* Group 1 - JS */
   "DOMEvent": {
diff --git a/browser/locales/en-US/chrome/browser/devtools/markers.properties b/browser/locales/en-US/chrome/browser/devtools/markers.properties
index ed0bbc5a06a..d84ceb509cc 100644
--- a/browser/locales/en-US/chrome/browser/devtools/markers.properties
+++ b/browser/locales/en-US/chrome/browser/devtools/markers.properties
@@ -17,6 +17,7 @@
 marker.label.styles=Recalculate Style
 marker.label.reflow=Layout
 marker.label.paint=Paint
+marker.label.composite=Composite Layers
 marker.label.javascript=Function Call
 marker.label.parseHTML=Parse HTML
 marker.label.parseXML=Parse XML
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 992b4582c59..d5f048b061e 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -277,10 +277,12 @@ private:
   // is stored on docshells directly.
   friend void mozilla::TimelineConsumers::AddConsumer(nsDocShell* aDocShell);
   friend void mozilla::TimelineConsumers::RemoveConsumer(nsDocShell* aDocShell);
-  friend void mozilla::TimelineConsumers::AddMarkerForDocShell(
-    nsDocShell* aDocShell, UniquePtr<TimelineMarker>&& aMarker);
   friend void mozilla::TimelineConsumers::AddMarkerForDocShell(
     nsDocShell* aDocShell, const char* aName, TracingMetadata aMetaData);
+  friend void mozilla::TimelineConsumers::AddMarkerForDocShell(
+    nsDocShell* aDocShell, const char* aName, const TimeStamp& aTime, TracingMetadata aMetaData);
+  friend void mozilla::TimelineConsumers::AddMarkerForDocShell(
+    nsDocShell* aDocShell, UniquePtr<TimelineMarker>&& aMarker);
 
 public:
   // Tell the favicon service that aNewURI has the same favicon as aOldURI.
diff --git a/docshell/base/timeline/AutoGlobalTimelineMarker.cpp b/docshell/base/timeline/AutoGlobalTimelineMarker.cpp
index 6f38b09a27a..a098443cce6 100644
--- a/docshell/base/timeline/AutoGlobalTimelineMarker.cpp
+++ b/docshell/base/timeline/AutoGlobalTimelineMarker.cpp
@@ -6,7 +6,7 @@
 
 #include "mozilla/AutoGlobalTimelineMarker.h"
 
-#include "mozilla/TimelineConsumers.h"
+#include "TimelineConsumers.h"
 #include "MainThreadUtils.h"
 
 namespace mozilla {
diff --git a/docshell/base/timeline/AutoTimelineMarker.cpp b/docshell/base/timeline/AutoTimelineMarker.cpp
index 8ac05e1e7a1..2ef8b144dbf 100644
--- a/docshell/base/timeline/AutoTimelineMarker.cpp
+++ b/docshell/base/timeline/AutoTimelineMarker.cpp
@@ -6,7 +6,7 @@
 
 #include "mozilla/AutoTimelineMarker.h"
 
-#include "mozilla/TimelineConsumers.h"
+#include "TimelineConsumers.h"
 #include "MainThreadUtils.h"
 #include "nsDocShell.h"
 
diff --git a/docshell/base/timeline/ObservedDocShell.cpp b/docshell/base/timeline/ObservedDocShell.cpp
index 613ca93d623..03abe410447 100644
--- a/docshell/base/timeline/ObservedDocShell.cpp
+++ b/docshell/base/timeline/ObservedDocShell.cpp
@@ -15,13 +15,6 @@ ObservedDocShell::ObservedDocShell(nsDocShell* aDocShell)
   : mDocShell(aDocShell)
 {}
 
-void
-ObservedDocShell::AddMarker(const char* aName, TracingMetadata aMetaData)
-{
-  TimelineMarker* marker = new TimelineMarker(mDocShell, aName, aMetaData);
-  mTimelineMarkers.AppendElement(marker);
-}
-
 void
 ObservedDocShell::AddMarker(UniquePtr<TimelineMarker>&& aMarker)
 {
diff --git a/docshell/base/timeline/ObservedDocShell.h b/docshell/base/timeline/ObservedDocShell.h
index e0932b277ed..e3fd11e6571 100644
--- a/docshell/base/timeline/ObservedDocShell.h
+++ b/docshell/base/timeline/ObservedDocShell.h
@@ -7,7 +7,6 @@
 #ifndef ObservedDocShell_h_
 #define ObservedDocShell_h_
 
-#include "GeckoProfiler.h"
 #include "nsTArray.h"
 #include "mozilla/nsRefPtr.h"
 
@@ -33,7 +32,6 @@ public:
   explicit ObservedDocShell(nsDocShell* aDocShell);
   nsDocShell* operator*() const { return mDocShell.get(); }
 
-  void AddMarker(const char* aName, TracingMetadata aMetaData);
   void AddMarker(UniquePtr<TimelineMarker>&& aMarker);
   void ClearMarkers();
   void PopMarkers(JSContext* aCx, nsTArray<dom::ProfileTimelineMarker>& aStore);
diff --git a/docshell/base/timeline/TimelineConsumers.cpp b/docshell/base/timeline/TimelineConsumers.cpp
index 13f0a05abda..e099f3043c0 100644
--- a/docshell/base/timeline/TimelineConsumers.cpp
+++ b/docshell/base/timeline/TimelineConsumers.cpp
@@ -65,6 +65,27 @@ TimelineConsumers::GetKnownDocShells(Vector<nsRefPtr<nsDocShell>>& aStore)
   return true;
 }
 
+void
+TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
+                                        const char* aName,
+                                        TracingMetadata aMetaData)
+{
+  if (aDocShell->IsObserved()) {
+    aDocShell->mObserved->AddMarker(Move(MakeUnique<TimelineMarker>(aDocShell, aName, aMetaData)));
+  }
+}
+
+void
+TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
+                                        const char* aName,
+                                        const TimeStamp& aTime,
+                                        TracingMetadata aMetaData)
+{
+  if (aDocShell->IsObserved()) {
+    aDocShell->mObserved->AddMarker(Move(MakeUnique<TimelineMarker>(aDocShell, aName, aTime, aMetaData)));
+  }
+}
+
 void
 TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
                                         UniquePtr<TimelineMarker>&& aMarker)
@@ -75,17 +96,33 @@ TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
 }
 
 void
-TimelineConsumers::AddMarkerForDocShell(nsDocShell* aDocShell,
-                                        const char* aName, TracingMetadata aMetaData)
+TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                        const char* aName,
+                                        TracingMetadata aMetaData)
 {
-  if (aDocShell->IsObserved()) {
-    aDocShell->mObserved->AddMarker(aName, aMetaData);
-  }
+  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), aName, aMetaData);
+}
+
+void
+TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                        const char* aName,
+                                        const TimeStamp& aTime,
+                                        TracingMetadata aMetaData)
+{
+  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), aName, aTime, aMetaData);
+}
+
+void
+TimelineConsumers::AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                        UniquePtr<TimelineMarker>&& aMarker)
+{
+  AddMarkerForDocShell(static_cast<nsDocShell*>(aDocShell), Move(aMarker));
 }
 
 void
 TimelineConsumers::AddMarkerForDocShellsList(Vector<nsRefPtr<nsDocShell>>& aDocShells,
-                                             const char* aName, TracingMetadata aMetaData)
+                                             const char* aName,
+                                             TracingMetadata aMetaData)
 {
   for (Vector<nsRefPtr<nsDocShell>>::Range range = aDocShells.all();
        !range.empty();
@@ -95,7 +132,8 @@ TimelineConsumers::AddMarkerForDocShellsList(Vector<nsRefPtr<nsDocShell>>& aDocS
 }
 
 void
-TimelineConsumers::AddMarkerForAllObservedDocShells(const char* aName, TracingMetadata aMetaData)
+TimelineConsumers::AddMarkerForAllObservedDocShells(const char* aName,
+                                                    TracingMetadata aMetaData)
 {
   Vector<nsRefPtr<nsDocShell>> docShells;
   if (!GetKnownDocShells(docShells)) {
diff --git a/docshell/base/timeline/TimelineConsumers.h b/docshell/base/timeline/TimelineConsumers.h
index 3540a4287cf..263df46b13a 100644
--- a/docshell/base/timeline/TimelineConsumers.h
+++ b/docshell/base/timeline/TimelineConsumers.h
@@ -10,11 +10,14 @@
 #include "mozilla/UniquePtr.h"
 #include "mozilla/LinkedList.h"
 #include "mozilla/Vector.h"
-#include "timeline/ObservedDocShell.h"
+#include "GeckoProfiler.h"
 
 class nsDocShell;
+class nsIDocShell;
+class TimelineMarker;
 
 namespace mozilla {
+class ObservedDocShell;
 
 class TimelineConsumers
 {
@@ -30,16 +33,49 @@ public:
   static bool IsEmpty();
   static bool GetKnownDocShells(Vector<nsRefPtr<nsDocShell>>& aStore);
 
-  // Methods for adding markers to appropriate docshells. These will only add
-  // markers if the docshell is currently being observed by a timeline.
+  // Methods for adding markers relevant for particular docshells, or generic
+  // (meaning that they either can't be tied to a particular docshell, or one
+  // wasn't accessible in the part of the codebase where they're instantiated).
+
+  // These will only add markers if at least one docshell is currently being
+  // observed by a timeline. Markers tied to a particular docshell won't be
+  // created unless that docshell is specifically being currently observed.
   // See nsIDocShell::recordProfileTimelineMarkers
+
+  // These methods create a custom marker from a name and some metadata,
+  // relevant for a specific docshell.
+  static void AddMarkerForDocShell(nsDocShell* aDocShell,
+                                   const char* aName,
+                                   TracingMetadata aMetaData);
+  static void AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                   const char* aName,
+                                   TracingMetadata aMetaData);
+
+  static void AddMarkerForDocShell(nsDocShell* aDocShell,
+                                   const char* aName,
+                                   const TimeStamp& aTime,
+                                   TracingMetadata aMetaData);
+  static void AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                   const char* aName,
+                                   const TimeStamp& aTime,
+                                   TracingMetadata aMetaData);
+
+  // These methods register and receive ownership of an already created marker,
+  // relevant for a specific docshell.
   static void AddMarkerForDocShell(nsDocShell* aDocShell,
                                    UniquePtr<TimelineMarker>&& aMarker);
-  static void AddMarkerForDocShell(nsDocShell* aDocShell,
-                                   const char* aName, TracingMetadata aMetaData);
+  static void AddMarkerForDocShell(nsIDocShell* aDocShell,
+                                   UniquePtr<TimelineMarker>&& aMarker);
+
+  // This method creates custom markers, relevant for a list of docshells.
   static void AddMarkerForDocShellsList(Vector<nsRefPtr<nsDocShell>>& aDocShells,
-                                        const char* aName, TracingMetadata aMetaData);
-  static void AddMarkerForAllObservedDocShells(const char* aName, TracingMetadata aMetaData);
+                                        const char* aName,
+                                        TracingMetadata aMetaData);
+
+  // This method creates custom markers, none of which have to be tied to a
+  // particular docshell.
+  static void AddMarkerForAllObservedDocShells(const char* aName,
+                                               TracingMetadata aMetaData);
 };
 
 } // namespace mozilla
diff --git a/docshell/base/timeline/TimelineMarker.cpp b/docshell/base/timeline/TimelineMarker.cpp
index 90f70f4b04e..51a78fbcfe7 100644
--- a/docshell/base/timeline/TimelineMarker.cpp
+++ b/docshell/base/timeline/TimelineMarker.cpp
@@ -20,6 +20,15 @@ TimelineMarker::TimelineMarker(nsDocShell* aDocShell, const char* aName,
   }
 }
 
+TimelineMarker::TimelineMarker(nsDocShell* aDocShell, const char* aName,
+                               const mozilla::TimeStamp& aTime,
+                               TracingMetadata aMetaData)
+  : TimelineMarker(aDocShell, aName, aMetaData)
+{
+  bool isInconsistent = false;
+  mTime = (aTime - mozilla::TimeStamp::ProcessCreation(isInconsistent)).ToMilliseconds();
+}
+
 TimelineMarker::TimelineMarker(nsDocShell* aDocShell, const char* aName,
                                TracingMetadata aMetaData,
                                const nsAString& aCause,
diff --git a/docshell/base/timeline/TimelineMarker.h b/docshell/base/timeline/TimelineMarker.h
index 25e6e2e8e53..49f99b39e4f 100644
--- a/docshell/base/timeline/TimelineMarker.h
+++ b/docshell/base/timeline/TimelineMarker.h
@@ -26,6 +26,10 @@ public:
   TimelineMarker(nsDocShell* aDocShell, const char* aName,
                  TracingMetadata aMetaData);
 
+  TimelineMarker(nsDocShell* aDocShell, const char* aName,
+                 const mozilla::TimeStamp& aTime,
+                 TracingMetadata aMetaData);
+
   TimelineMarker(nsDocShell* aDocShell, const char* aName,
                  TracingMetadata aMetaData,
                  const nsAString& aCause,
diff --git a/docshell/base/timeline/moz.build b/docshell/base/timeline/moz.build
index 92b12fded4a..0078dbcdf91 100644
--- a/docshell/base/timeline/moz.build
+++ b/docshell/base/timeline/moz.build
@@ -7,7 +7,9 @@
 EXPORTS.mozilla += [
     'AutoGlobalTimelineMarker.h',
     'AutoTimelineMarker.h',
+    'ObservedDocShell.h',
     'TimelineConsumers.h',
+    'TimelineMarker.h',
 ]
 
 UNIFIED_SOURCES += [
diff --git a/dom/ipc/TabChild.cpp b/dom/ipc/TabChild.cpp
index 2ea68ecd1c3..98e617b656d 100644
--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -2862,7 +2862,9 @@ TabChild::GetFrom(uint64_t aLayersId)
 }
 
 void
-TabChild::DidComposite(uint64_t aTransactionId)
+TabChild::DidComposite(uint64_t aTransactionId,
+                       const TimeStamp& aCompositeStart,
+                       const TimeStamp& aCompositeEnd)
 {
   MOZ_ASSERT(mPuppetWidget);
   MOZ_ASSERT(mPuppetWidget->GetLayerManager());
@@ -2871,7 +2873,8 @@ TabChild::DidComposite(uint64_t aTransactionId)
 
   ClientLayerManager *manager =
     static_cast<ClientLayerManager*>(mPuppetWidget->GetLayerManager());
-  manager->DidComposite(aTransactionId);
+
+  manager->DidComposite(aTransactionId, aCompositeStart, aCompositeEnd);
 }
 
 void
diff --git a/dom/ipc/TabChild.h b/dom/ipc/TabChild.h
index 00d85ee4a39..09c977f4b11 100644
--- a/dom/ipc/TabChild.h
+++ b/dom/ipc/TabChild.h
@@ -461,7 +461,10 @@ public:
     static TabChild* GetFrom(nsIPresShell* aPresShell);
     static TabChild* GetFrom(uint64_t aLayersId);
 
-    void DidComposite(uint64_t aTransactionId);
+    void DidComposite(uint64_t aTransactionId,
+                      const TimeStamp& aCompositeStart,
+                      const TimeStamp& aCompositeEnd);
+
     void ClearCachedResources();
 
     static inline TabChild*
diff --git a/gfx/layers/client/ClientLayerManager.cpp b/gfx/layers/client/ClientLayerManager.cpp
index 4f0b0f42e7d..53a0716eee6 100644
--- a/gfx/layers/client/ClientLayerManager.cpp
+++ b/gfx/layers/client/ClientLayerManager.cpp
@@ -110,7 +110,8 @@ ClientLayerManager::ClientLayerManager(nsIWidget* aWidget)
 ClientLayerManager::~ClientLayerManager()
 {
   if (mTransactionIdAllocator) {
-    DidComposite(mLatestTransactionId);
+    TimeStamp now = TimeStamp::Now();
+    DidComposite(mLatestTransactionId, now, now);
   }
   mMemoryPressureObserver->Destroy();
   ClearCachedResources();
@@ -384,16 +385,18 @@ ClientLayerManager::Composite()
 }
 
 void
-ClientLayerManager::DidComposite(uint64_t aTransactionId)
+ClientLayerManager::DidComposite(uint64_t aTransactionId,
+                                 const TimeStamp& aCompositeStart,
+                                 const TimeStamp& aCompositeEnd)
 {
   MOZ_ASSERT(mWidget);
   nsIWidgetListener *listener = mWidget->GetWidgetListener();
   if (listener) {
-    listener->DidCompositeWindow();
+    listener->DidCompositeWindow(aCompositeStart, aCompositeEnd);
   }
   listener = mWidget->GetAttachedWidgetListener();
   if (listener) {
-    listener->DidCompositeWindow();
+    listener->DidCompositeWindow(aCompositeStart, aCompositeEnd);
   }
   mTransactionIdAllocator->NotifyTransactionCompleted(aTransactionId);
 }
diff --git a/gfx/layers/client/ClientLayerManager.h b/gfx/layers/client/ClientLayerManager.h
index 32e8ba2b2dc..9defd20bdfa 100644
--- a/gfx/layers/client/ClientLayerManager.h
+++ b/gfx/layers/client/ClientLayerManager.h
@@ -203,7 +203,9 @@ public:
   virtual bool RequestOverfill(mozilla::dom::OverfillCallback* aCallback) override;
   virtual void RunOverfillCallback(const uint32_t aOverfill) override;
 
-  void DidComposite(uint64_t aTransactionId);
+  void DidComposite(uint64_t aTransactionId,
+                    const mozilla::TimeStamp& aCompositeStart,
+                    const mozilla::TimeStamp& aCompositeEnd);
 
   virtual bool SupportsMixBlendModes(EnumSet<gfx::CompositionOp>& aMixBlendModes) override
   {
diff --git a/gfx/layers/ipc/CompositorChild.cpp b/gfx/layers/ipc/CompositorChild.cpp
index b287e1e7ee1..1618b39b3f8 100644
--- a/gfx/layers/ipc/CompositorChild.cpp
+++ b/gfx/layers/ipc/CompositorChild.cpp
@@ -345,15 +345,17 @@ CompositorChild::RecvUpdatePluginVisibility(const uintptr_t& aOwnerWidget,
 }
 
 bool
-CompositorChild::RecvDidComposite(const uint64_t& aId, const uint64_t& aTransactionId)
+CompositorChild::RecvDidComposite(const uint64_t& aId, const uint64_t& aTransactionId,
+                                  const TimeStamp& aCompositeStart,
+                                  const TimeStamp& aCompositeEnd)
 {
   if (mLayerManager) {
     MOZ_ASSERT(aId == 0);
-    mLayerManager->DidComposite(aTransactionId);
+    mLayerManager->DidComposite(aTransactionId, aCompositeStart, aCompositeEnd);
   } else if (aId != 0) {
     dom::TabChild *child = dom::TabChild::GetFrom(aId);
     if (child) {
-      child->DidComposite(aTransactionId);
+      child->DidComposite(aTransactionId, aCompositeStart, aCompositeEnd);
     }
   }
   return true;
diff --git a/gfx/layers/ipc/CompositorChild.h b/gfx/layers/ipc/CompositorChild.h
index 1710957dc79..447efad8576 100644
--- a/gfx/layers/ipc/CompositorChild.h
+++ b/gfx/layers/ipc/CompositorChild.h
@@ -74,7 +74,9 @@ public:
   RecvClearCachedResources(const uint64_t& id) override;
 
   virtual bool
-  RecvDidComposite(const uint64_t& aId, const uint64_t& aTransactionId) override;
+  RecvDidComposite(const uint64_t& aId, const uint64_t& aTransactionId,
+                   const TimeStamp& aCompositeStart,
+                   const TimeStamp& aCompositeEnd) override;
 
   virtual bool
   RecvInvalidateAll() override;
diff --git a/gfx/layers/ipc/CompositorParent.cpp b/gfx/layers/ipc/CompositorParent.cpp
index eb7b7bc9900..edc8f436df5 100644
--- a/gfx/layers/ipc/CompositorParent.cpp
+++ b/gfx/layers/ipc/CompositorParent.cpp
@@ -831,7 +831,9 @@ CompositorParent::PauseComposition()
     mPaused = true;
 
     mCompositor->Pause();
-    DidComposite();
+
+    TimeStamp now = TimeStamp::Now();
+    DidComposite(now, now);
   }
 
   // if anyone's waiting to make sure that composition really got paused, tell them
@@ -1034,7 +1036,8 @@ CompositorParent::CompositeToTarget(DrawTarget* aTarget, const gfx::IntRect* aRe
 #endif
 
   if (!CanComposite()) {
-    DidComposite();
+    TimeStamp end = TimeStamp::Now();
+    DidComposite(start, end);
     return;
   }
 
@@ -1077,7 +1080,8 @@ CompositorParent::CompositeToTarget(DrawTarget* aTarget, const gfx::IntRect* aRe
   mLayerManager->EndTransaction(time);
 
   if (!aTarget) {
-    DidComposite();
+    TimeStamp end = TimeStamp::Now();
+    DidComposite(start, end);
   }
 
   // We're not really taking advantage of the stored composite-again-time here.
@@ -1193,7 +1197,8 @@ CompositorParent::ShadowLayersUpdated(LayerTransactionParent* aLayerTree,
   if (aScheduleComposite) {
     ScheduleComposition();
     if (mPaused) {
-      DidComposite();
+      TimeStamp now = TimeStamp::Now();
+      DidComposite(now, now);
     }
   }
   mLayerManager->NotifyShadowTreeTransaction();
@@ -1226,7 +1231,8 @@ CompositorParent::SetTestSampleTime(LayerTransactionParent* aLayerTree,
     if (!requestNextFrame) {
       CancelCurrentCompositeTask();
       // Pretend we composited in case someone is wating for this event.
-      DidComposite();
+      TimeStamp now = TimeStamp::Now();
+      DidComposite(now, now);
     }
   }
 
@@ -1258,7 +1264,8 @@ CompositorParent::ApplyAsyncProperties(LayerTransactionParent* aLayerTree)
     if (!requestNextFrame) {
       CancelCurrentCompositeTask();
       // Pretend we composited in case someone is waiting for this event.
-      DidComposite();
+      TimeStamp now = TimeStamp::Now();
+      DidComposite(now, now);
     }
   }
 }
@@ -1717,7 +1724,9 @@ public:
 
   virtual AsyncCompositionManager* GetCompositionManager(LayerTransactionParent* aParent) override;
 
-  void DidComposite(uint64_t aId);
+  void DidComposite(uint64_t aId,
+                    TimeStamp& aCompositeStart,
+                    TimeStamp& aCompositeEnd);
 
 private:
   // Private destructor, to discourage deletion outside of Release():
@@ -1738,10 +1747,11 @@ private:
 };
 
 void
-CompositorParent::DidComposite()
+CompositorParent::DidComposite(TimeStamp& aCompositeStart,
+                               TimeStamp& aCompositeEnd)
 {
   if (mPendingTransaction) {
-    unused << SendDidComposite(0, mPendingTransaction);
+    unused << SendDidComposite(0, mPendingTransaction, aCompositeStart, aCompositeEnd);
     mPendingTransaction = 0;
   }
   if (mLayerManager) {
@@ -1757,7 +1767,8 @@ CompositorParent::DidComposite()
        it != sIndirectLayerTrees.end(); it++) {
     LayerTreeState* lts = &it->second;
     if (lts->mParent == this && lts->mCrossProcessParent) {
-      static_cast<CrossProcessCompositorParent*>(lts->mCrossProcessParent)->DidComposite(it->first);
+      static_cast<CrossProcessCompositorParent*>(lts->mCrossProcessParent)->DidComposite(
+        it->first, aCompositeStart, aCompositeEnd);
     }
   }
 }
@@ -2041,12 +2052,14 @@ UpdatePluginWindowState(uint64_t aId)
 #endif // #if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
 
 void
-CrossProcessCompositorParent::DidComposite(uint64_t aId)
+CrossProcessCompositorParent::DidComposite(uint64_t aId,
+                                           TimeStamp& aCompositeStart,
+                                           TimeStamp& aCompositeEnd)
 {
   sIndirectLayerTreesLock->AssertCurrentThreadOwns();
   LayerTransactionParent *layerTree = sIndirectLayerTrees[aId].mLayerTree;
   if (layerTree && layerTree->GetPendingTransactionId()) {
-    unused << SendDidComposite(aId, layerTree->GetPendingTransactionId());
+    unused << SendDidComposite(aId, layerTree->GetPendingTransactionId(), aCompositeStart, aCompositeEnd);
     layerTree->SetPendingTransactionId(0);
   }
 #if defined(XP_WIN) || defined(MOZ_WIDGET_GTK)
diff --git a/gfx/layers/ipc/CompositorParent.h b/gfx/layers/ipc/CompositorParent.h
index 95a05d264f7..4ac9e3d085b 100644
--- a/gfx/layers/ipc/CompositorParent.h
+++ b/gfx/layers/ipc/CompositorParent.h
@@ -439,7 +439,7 @@ protected:
    */
   bool CanComposite();
 
-  void DidComposite();
+  void DidComposite(TimeStamp& aCompositeStart, TimeStamp& aCompositeEnd);
 
   nsRefPtr<LayerManagerComposite> mLayerManager;
   nsRefPtr<Compositor> mCompositor;
diff --git a/gfx/layers/ipc/PCompositor.ipdl b/gfx/layers/ipc/PCompositor.ipdl
index eb01970da15..e53d66dc708 100644
--- a/gfx/layers/ipc/PCompositor.ipdl
+++ b/gfx/layers/ipc/PCompositor.ipdl
@@ -45,7 +45,8 @@ child:
   // the root layer tree).
   // transactionId is the id of the transaction before this composite, or 0
   // if there was no transaction since the last composite.
-  async DidComposite(uint64_t id, uint64_t transactionId);
+  async DidComposite(uint64_t id, uint64_t transactionId,
+                     TimeStamp compositeStart, TimeStamp compositeEnd);
 
   // The parent sends the child the requested fill ratio numbers.
   async Overfill(uint32_t aOverfill);
diff --git a/view/nsView.cpp b/view/nsView.cpp
index eefe5b849bf..a355c6f15d7 100644
--- a/view/nsView.cpp
+++ b/view/nsView.cpp
@@ -18,6 +18,7 @@
 #include "nsXULPopupManager.h"
 #include "nsIWidgetListener.h"
 #include "nsContentUtils.h" // for nsAutoScriptBlocker
+#include "mozilla/TimelineConsumers.h"
 
 using namespace mozilla;
 
@@ -1071,12 +1072,28 @@ nsView::DidPaintWindow()
 }
 
 void
-nsView::DidCompositeWindow()
+nsView::DidCompositeWindow(const TimeStamp& aCompositeStart,
+                           const TimeStamp& aCompositeEnd)
 {
   nsIPresShell* presShell = mViewManager->GetPresShell();
   if (presShell) {
     nsAutoScriptBlocker scriptBlocker;
-    presShell->GetPresContext()->GetDisplayRootPresContext()->GetRootPresContext()->NotifyDidPaintForSubtree(nsIPresShell::PAINT_COMPOSITE);
+
+    nsPresContext* context = presShell->GetPresContext();
+    context->GetDisplayRootPresContext()->GetRootPresContext()->NotifyDidPaintForSubtree(nsIPresShell::PAINT_COMPOSITE);
+
+    // If the two timestamps are identical, this was likely a fake composite
+    // event which wouldn't be terribly useful to display.
+    if (aCompositeStart == aCompositeEnd) {
+      return;
+    }
+
+    nsIDocShell* docShell = context->GetDocShell();
+
+    TimelineConsumers::AddMarkerForDocShell(docShell,
+      "Composite", aCompositeStart, TRACING_INTERVAL_START);
+    TimelineConsumers::AddMarkerForDocShell(docShell,
+      "Composite", aCompositeEnd, TRACING_INTERVAL_END);
   }
 }
 
diff --git a/view/nsView.h b/view/nsView.h
index e4980a7a7fe..9b5dad5fdb4 100644
--- a/view/nsView.h
+++ b/view/nsView.h
@@ -381,7 +381,8 @@ public:
   virtual void WillPaintWindow(nsIWidget* aWidget) override;
   virtual bool PaintWindow(nsIWidget* aWidget, nsIntRegion aRegion) override;
   virtual void DidPaintWindow() override;
-  virtual void DidCompositeWindow() override;
+  virtual void DidCompositeWindow(const mozilla::TimeStamp& aCompositeStart,
+                                  const mozilla::TimeStamp& aCompositeEnd) override;
   virtual void RequestRepaint() override;
   virtual nsEventStatus HandleEvent(mozilla::WidgetGUIEvent* aEvent,
                                     bool aUseAttachedEvents) override;
diff --git a/widget/nsIWidgetListener.cpp b/widget/nsIWidgetListener.cpp
index 51e88d84cd8..050ad8de131 100644
--- a/widget/nsIWidgetListener.cpp
+++ b/widget/nsIWidgetListener.cpp
@@ -107,7 +107,8 @@ nsIWidgetListener::DidPaintWindow()
 }
 
 void
-nsIWidgetListener::DidCompositeWindow()
+nsIWidgetListener::DidCompositeWindow(const TimeStamp& aCompositeStart,
+                                      const TimeStamp& aCompositeEnd)
 {
 }
 
diff --git a/widget/nsIWidgetListener.h b/widget/nsIWidgetListener.h
index 11ef193fe21..153e0dd482f 100644
--- a/widget/nsIWidgetListener.h
+++ b/widget/nsIWidgetListener.h
@@ -8,6 +8,7 @@
 #include <stdint.h>
 
 #include "mozilla/EventForwards.h"
+#include "mozilla/TimeStamp.h"
 
 class nsView;
 class nsIntRegion;
@@ -135,7 +136,8 @@ public:
    */
   virtual void DidPaintWindow();
 
-  virtual void DidCompositeWindow();
+  virtual void DidCompositeWindow(const mozilla::TimeStamp& aCompositeStart,
+                                  const mozilla::TimeStamp& aCompositeEnd);
 
   /**
    * Request that layout schedules a repaint on the next refresh driver tick.