--- a/layout/base/PresShell.cpp
+++ b/layout/base/PresShell.cpp
@@ -848,17 +848,17 @@ PresShell::PresShell()
   , mIsLastChromeOnlyEscapeKeyConsumed(false)
   , mHasReceivedPaintMessage(false)
 {
 #ifdef MOZ_REFLOW_PERF
   mReflowCountMgr = new ReflowCountMgr();
   mReflowCountMgr->SetPresContext(mPresContext);
   mReflowCountMgr->SetPresShell(this);
 #endif
-  mLoadBegin = TimeStamp::Now();
+  mLastOSWake = mLoadBegin = TimeStamp::Now();
 
   mSelectionFlags = nsISelectionDisplay::DISPLAY_TEXT | nsISelectionDisplay::DISPLAY_IMAGES;
   mIsThemeSupportDisabled = false;
   mIsActive = true;
   // FIXME/bug 735029: find a better solution to this problem
   mIsFirstPaint = true;
   mPresShellId = sNextPresShellId++;
   mFrozen = false;
@@ -1018,16 +1018,17 @@ PresShell::Init(nsIDocument* aDocument,
 
   {
     nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
     if (os) {
 #ifdef MOZ_XUL
       os->AddObserver(this, "chrome-flush-skin-caches", false);
 #endif
       os->AddObserver(this, "memory-pressure", false);
+      os->AddObserver(this, NS_WIDGET_WAKE_OBSERVER_TOPIC, false);
     }
   }
 
 #ifdef MOZ_REFLOW_PERF
     if (mReflowCountMgr) {
       bool paintFrameCounts =
         Preferences::GetBool("layout.reflow.showframecounts");
 
@@ -1245,16 +1246,17 @@ PresShell::Destroy()
 
   {
     nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
     if (os) {
 #ifdef MOZ_XUL
       os->RemoveObserver(this, "chrome-flush-skin-caches");
 #endif
       os->RemoveObserver(this, "memory-pressure");
+      os->RemoveObserver(this, NS_WIDGET_WAKE_OBSERVER_TOPIC);
     }
   }
 
   // If our paint suppression timer is still active, kill it.
   if (mPaintSuppressionTimer) {
     mPaintSuppressionTimer->Cancel();
     mPaintSuppressionTimer = nullptr;
   }
@@ -8248,16 +8250,17 @@ PresShell::HandleEventInternal(WidgetEve
       break;
     default:
       break;
     }
   }
 
   if (Telemetry::CanRecordBase() &&
       !aEvent->mTimeStamp.IsNull() &&
+      aEvent->mTimeStamp > mLastOSWake &&
       aEvent->AsInputEvent()) {
     double millis = (TimeStamp::Now() - aEvent->mTimeStamp).ToMilliseconds();
     Telemetry::Accumulate(Telemetry::INPUT_EVENT_RESPONSE_MS, millis);
     if (mDocument && mDocument->GetReadyStateEnum() != nsIDocument::READYSTATE_COMPLETE) {
       Telemetry::Accumulate(Telemetry::LOAD_INPUT_EVENT_RESPONSE_MS, millis);
     }
   }
 
@@ -9683,16 +9686,20 @@ PresShell::Observe(nsISupports* aSubject
 
   if (!nsCRT::strcmp(aTopic, "memory-pressure")) {
     if (!AssumeAllFramesVisible() && mPresContext->IsRootContentDocument()) {
       DoUpdateApproximateFrameVisibility(/* aRemoveOnly = */ true);
     }
     return NS_OK;
   }
 
+  if (!nsCRT::strcmp(aTopic, NS_WIDGET_WAKE_OBSERVER_TOPIC)) {
+    mLastOSWake = TimeStamp::Now();
+  }
+
   NS_WARNING("unrecognized topic in PresShell::Observe");
   return NS_ERROR_FAILURE;
 }
 
 bool
 nsIPresShell::AddRefreshObserverInternal(nsARefreshObserver* aObserver,
                                          FlushType aFlushType)
 {

--- a/layout/base/PresShell.h
+++ b/layout/base/PresShell.h
@@ -901,13 +901,15 @@ protected:
   bool                      mIsLastChromeOnlyEscapeKeyConsumed : 1;
 
   // Whether the widget has received a paint message yet.
   bool                      mHasReceivedPaintMessage : 1;
 
   bool                      mIsLastKeyDownCanceled : 1;
 
   static bool               sDisableNonTestMouseEvents;
+
+  mozilla::TimeStamp        mLastOSWake;
 };
 
 } // namespace mozilla
 
 #endif // mozilla_PresShell_h