diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp
index 8a60f08188df..d712cffbbaef 100644
--- a/dom/base/nsJSEnvironment.cpp
+++ b/dom/base/nsJSEnvironment.cpp
@@ -286,6 +286,9 @@ FindExceptionStackForConsoleReport(nsPIDOMWindowInner* win,
 static PRTime
 GetCollectionTimeDelta()
 {
+  if (recordreplay::IsRecordingOrReplaying()) {
+    return 0;
+  }
   PRTime now = PR_Now();
   if (sFirstCollectionTime) {
     return now - sFirstCollectionTime;
diff --git a/js/src/gc/GC.cpp b/js/src/gc/GC.cpp
index e7fd3d1b415d..9b3e82c280d5 100644
--- a/js/src/gc/GC.cpp
+++ b/js/src/gc/GC.cpp
@@ -6766,7 +6766,7 @@ GCRuntime::finishCollection()
     marker.stop();
     clearBufferedGrayRoots();
 
-    auto currentTime = mozilla::TimeStamp::Now();
+    auto currentTime = ReallyNow();
     schedulingState.updateHighFrequencyMode(lastGCTime, currentTime, tunables);
 
     for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
diff --git a/js/src/gc/Memory.cpp b/js/src/gc/Memory.cpp
index 1f83cd6770b4..ce9d9fd945d0 100644
--- a/js/src/gc/Memory.cpp
+++ b/js/src/gc/Memory.cpp
@@ -286,6 +286,8 @@ MarkPagesInUse(void* p, size_t size)
 size_t
 GetPageFaultCount()
 {
+    if (mozilla::recordreplay::IsRecordingOrReplaying())
+        return 0;
     PROCESS_MEMORY_COUNTERS pmc;
     if (!GetProcessMemoryInfo(GetCurrentProcess(), &pmc, sizeof(pmc)))
         return 0;
@@ -813,6 +815,8 @@ MarkPagesInUse(void* p, size_t size)
 size_t
 GetPageFaultCount()
 {
+    if (mozilla::recordreplay::IsRecordingOrReplaying())
+        return 0;
     struct rusage usage;
     int err = getrusage(RUSAGE_SELF, &usage);
     if (err)
diff --git a/js/src/gc/Nursery.cpp b/js/src/gc/Nursery.cpp
index b7a62de115e2..d78da3f2b04e 100644
--- a/js/src/gc/Nursery.cpp
+++ b/js/src/gc/Nursery.cpp
@@ -669,13 +669,13 @@ js::Nursery::maybeClearProfileDurations()
 inline void
 js::Nursery::startProfile(ProfileKey key)
 {
-    startTimes_[key] = TimeStamp::Now();
+    startTimes_[key] = ReallyNow();
 }
 
 inline void
 js::Nursery::endProfile(ProfileKey key)
 {
-    profileDurations_[key] = TimeStamp::Now() - startTimes_[key];
+    profileDurations_[key] = ReallyNow() - startTimes_[key];
     totalDurations_[key] += profileDurations_[key];
 }
 
diff --git a/js/src/gc/Statistics.cpp b/js/src/gc/Statistics.cpp
index 6b68a14ee01d..1875a8d95569 100644
--- a/js/src/gc/Statistics.cpp
+++ b/js/src/gc/Statistics.cpp
@@ -1051,7 +1051,7 @@ Statistics::beginSlice(const ZoneGCStats& zoneStats, JSGCInvocationKind gckind,
 
     if (!slices_.emplaceBack(budget,
                              reason,
-                             TimeStamp::Now(),
+                             ReallyNow(),
                              GetPageFaultCount(),
                              runtime->gc.state()))
     {
@@ -1083,7 +1083,7 @@ Statistics::endSlice()
 
     if (!aborted) {
         auto& slice = slices_.back();
-        slice.end = TimeStamp::Now();
+        slice.end = ReallyNow();
         slice.endFaults = GetPageFaultCount();
         slice.finalState = runtime->gc.state();
 
@@ -1246,7 +1246,7 @@ Statistics::resumePhases()
     {
         Phase resumePhase = suspendedPhases.popCopy();
         if (resumePhase == Phase::MUTATOR)
-            timedGCTime += TimeStamp::Now() - timedGCStart;
+            timedGCTime += ReallyNow() - timedGCStart;
         recordPhaseBegin(resumePhase);
     }
 }
@@ -1277,7 +1277,7 @@ Statistics::recordPhaseBegin(Phase phase)
     Phase current = currentPhase();
     MOZ_ASSERT(phases[phase].parent == current);
 
-    TimeStamp now = TimeStamp::Now();
+    TimeStamp now = ReallyNow();
 
     if (current != Phase::NONE) {
         MOZ_ASSERT(now >= phaseStartTimes[currentPhase()], "Inconsistent time data; see bug 1400153");
@@ -1299,7 +1299,7 @@ Statistics::recordPhaseEnd(Phase phase)
 
     MOZ_ASSERT(phaseStartTimes[phase]);
 
-    TimeStamp now = TimeStamp::Now();
+    TimeStamp now = ReallyNow();
 
     // Make sure this phase ends after it starts.
     MOZ_ASSERT(now >= phaseStartTimes[phase], "Inconsistent time data; see bug 1400153");
@@ -1383,7 +1383,7 @@ Statistics::recordParallelPhase(PhaseKind phaseKind, TimeDuration duration)
 TimeStamp
 Statistics::beginSCC()
 {
-    return TimeStamp::Now();
+    return ReallyNow();
 }
 
 void
@@ -1392,7 +1392,7 @@ Statistics::endSCC(unsigned scc, TimeStamp start)
     if (scc >= sccTimes.length() && !sccTimes.resize(scc + 1))
         return;
 
-    sccTimes[scc] += TimeStamp::Now() - start;
+    sccTimes[scc] += ReallyNow() - start;
 }
 
 /*
diff --git a/js/src/vm/HelperThreads.cpp b/js/src/vm/HelperThreads.cpp
index 6c837c4aca3a..fb62356ccb69 100644
--- a/js/src/vm/HelperThreads.cpp
+++ b/js/src/vm/HelperThreads.cpp
@@ -1560,7 +1560,7 @@ js::GCParallelTask::runFromMainThread(JSRuntime* rt)
 {
     assertNotStarted();
     MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(rt));
-    TimeStamp timeStart = TimeStamp::Now();
+    TimeStamp timeStart = ReallyNow();
     runTask();
     duration_ = TimeSince(timeStart);
 }
@@ -1575,7 +1575,7 @@ js::GCParallelTask::runFromHelperThread(AutoLockHelperThreadState& lock)
 
     {
         AutoUnlockHelperThreadState parallelSection(lock);
-        TimeStamp timeStart = TimeStamp::Now();
+        TimeStamp timeStart = ReallyNow();
         runTask();
         duration_ = TimeSince(timeStart);
     }
diff --git a/js/src/vm/Time.h b/js/src/vm/Time.h
index 597673b9f7ec..b6977e3ce3d3 100644
--- a/js/src/vm/Time.h
+++ b/js/src/vm/Time.h
@@ -132,6 +132,8 @@ PRMJ_FormatTime(char* buf, int buflen, const char* fmt, const PRMJTime* tm,
 static __inline uint64_t
 ReadTimestampCounter(void)
 {
+    if (mozilla::recordreplay::IsRecordingOrReplaying())
+        return 0;
     return __rdtsc();
 }
 
@@ -140,6 +142,8 @@ ReadTimestampCounter(void)
 static __inline__ uint64_t
 ReadTimestampCounter(void)
 {
+    if (mozilla::recordreplay::IsRecordingOrReplaying())
+        return 0;
     uint64_t x;
     __asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
     return x;
@@ -150,6 +154,8 @@ ReadTimestampCounter(void)
 static __inline__ uint64_t
 ReadTimestampCounter(void)
 {
+    if (mozilla::recordreplay::IsRecordingOrReplaying())
+        return 0;
     unsigned hi, lo;
     __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
     return ( (uint64_t)lo)|( ((uint64_t)hi)<<32 );