diff --git a/js/public/HeapAPI.h b/js/public/HeapAPI.h
index 79fa6232c794..969067e34033 100644
--- a/js/public/HeapAPI.h
+++ b/js/public/HeapAPI.h
@@ -383,6 +383,14 @@ IsIncrementalBarrierNeededOnTenuredGCThing(JS::shadow::Runtime *rt, const JS::GC
     return JS::shadow::Zone::asShadowZone(zone)->needsIncrementalBarrier();
 }
 
+/*
+ * Create an object providing access to the garbage collector's internal notion
+ * of the current state of memory (both GC heap memory and GCthing-controlled
+ * malloc memory.
+ */
+extern JS_PUBLIC_API(JSObject *)
+NewMemoryInfoObject(JSContext *cx);
+
 } /* namespace gc */
 } /* namespace js */
 
diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index 104ff8a16eac..6941e621b65f 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -752,6 +752,7 @@ class GCRuntime
     void removeBlackRootsTracer(JSTraceDataOp traceOp, void *data);
 
     void setMaxMallocBytes(size_t value);
+    int32_t getMallocBytes() const { return mallocBytesUntilGC; }
     void resetMallocBytes();
     bool isTooMuchMalloc() const { return mallocBytesUntilGC <= 0; }
     void updateMallocCounter(JS::Zone *zone, size_t nbytes);
@@ -781,6 +782,12 @@ class GCRuntime
     uint64_t gcNumber() { return number; }
     void incGcNumber() { ++number; }
 
+    uint64_t minorGCCount() { return minorGCNumber; }
+    void incMinorGcNumber() { ++minorGCNumber; }
+
+    uint64_t majorGCCount() { return majorGCNumber; }
+    void incMajorGcNumber() { ++majorGCNumber; }
+
     bool isIncrementalGc() { return isIncremental; }
     bool isFullGc() { return isFull; }
 
@@ -1062,6 +1069,9 @@ class GCRuntime
     /* Perform full GC if rt->keepAtoms() becomes false. */
     bool fullGCForAtomsRequested_;
 
+    /* Incremented at the start of every minor GC. */
+    uint64_t minorGCNumber;
+
     /* Incremented at the start of every major GC. */
     uint64_t majorGCNumber;
 
diff --git a/js/src/gc/Nursery.cpp b/js/src/gc/Nursery.cpp
index 251f023e6764..f14174cc1c4d 100644
--- a/js/src/gc/Nursery.cpp
+++ b/js/src/gc/Nursery.cpp
@@ -807,6 +807,8 @@ js::Nursery::collect(JSRuntime *rt, JS::gcreason::Reason reason, ObjectGroupList
         return;
     }
 
+    rt->gc.incMinorGcNumber();
+
     rt->gc.stats.count(gcstats::STAT_MINOR_GC);
 
     TraceMinorGCStart();
diff --git a/js/src/gc/Zone.h b/js/src/gc/Zone.h
index 8b72823714f7..f042c6e841fc 100644
--- a/js/src/gc/Zone.h
+++ b/js/src/gc/Zone.h
@@ -43,7 +43,7 @@ class ZoneHeapThreshold
 
     double gcHeapGrowthFactor() const { return gcHeapGrowthFactor_; }
     size_t gcTriggerBytes() const { return gcTriggerBytes_; }
-    bool isCloseToAllocTrigger(const js::gc::HeapUsage& usage, bool highFrequencyGC) const;
+    double allocTrigger(bool highFrequencyGC) const;
 
     void updateAfterGC(size_t lastBytes, JSGCInvocationKind gckind,
                        const GCSchedulingTunables &tunables, const GCSchedulingState &state);
diff --git a/js/src/jsapi.h b/js/src/jsapi.h
index 3ac22f8dba50..3e79cdc61bc4 100644
--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -5257,7 +5257,6 @@ GetSavedFrameParent(JSContext *cx, HandleObject savedFrame, MutableHandleObject
 extern JS_PUBLIC_API(bool)
 StringifySavedFrameStack(JSContext *cx, HandleObject stack, MutableHandleString stringp);
 
-
 } /* namespace JS */
 
 #endif /* jsapi_h */
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index d7c601a5351b..7237a4836e42 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -1068,6 +1068,7 @@ GCRuntime::GCRuntime(JSRuntime *rt) :
     majorGCTriggerReason(JS::gcreason::NO_REASON),
     minorGCTriggerReason(JS::gcreason::NO_REASON),
     fullGCForAtomsRequested_(false),
+    minorGCNumber(0),
     majorGCNumber(0),
     jitReleaseNumber(0),
     number(0),
@@ -1660,11 +1661,10 @@ GCRuntime::onTooMuchMalloc()
         mallocGCTriggered = triggerGC(JS::gcreason::TOO_MUCH_MALLOC);
 }
 
-bool
-ZoneHeapThreshold::isCloseToAllocTrigger(const js::gc::HeapUsage& usage, bool highFrequencyGC) const
+double
+ZoneHeapThreshold::allocTrigger(bool highFrequencyGC) const
 {
-    double factor = highFrequencyGC ? 0.85 : 0.9;
-    return usage.gcBytes() >= factor * gcTriggerBytes();
+    return (highFrequencyGC ? 0.85 : 0.9) * gcTriggerBytes();
 }
 
 /* static */ double
@@ -3071,7 +3071,7 @@ GCRuntime::maybeGC(Zone *zone)
         return true;
 
     if (zone->usage.gcBytes() > 1024 * 1024 &&
-        zone->threshold.isCloseToAllocTrigger(zone->usage, schedulingState.inHighFrequencyGCMode()) &&
+        zone->usage.gcBytes() >= zone->threshold.allocTrigger(schedulingState.inHighFrequencyGCMode()) &&
         !isIncrementalGCInProgress() &&
         !isBackgroundSweeping())
     {
@@ -5911,7 +5911,7 @@ GCRuntime::gcCycle(bool incremental, SliceBudget &budget, JS::gcreason::Reason r
 
     number++;
     if (!isIncrementalGCInProgress())
-        majorGCNumber++;
+        incMajorGcNumber();
 
     // It's ok if threads other than the main thread have suppressGC set, as
     // they are operating on zones which will not be collected from here.
@@ -6013,7 +6013,7 @@ GCRuntime::scanZonesBeforeGC()
             zone->scheduleGC();
 
         /* This is a heuristic to reduce the total number of collections. */
-        if (zone->threshold.isCloseToAllocTrigger(zone->usage, schedulingState.inHighFrequencyGCMode()))
+        if (zone->usage.gcBytes() >= zone->threshold.allocTrigger(schedulingState.inHighFrequencyGCMode()))
             zone->scheduleGC();
 
         zoneStats.zoneCount++;
@@ -7091,3 +7091,202 @@ JS::IsGenerationalGCEnabled(JSRuntime *rt)
 {
     return rt->gc.isGenerationalGCEnabled();
 }
+
+namespace js {
+namespace gc {
+namespace MemInfo {
+
+static bool
+GCBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.usage.gcBytes()));
+    return true;
+}
+
+static bool
+GCMaxBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.tunables.gcMaxBytes()));
+    return true;
+}
+
+static bool
+MallocBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.getMallocBytes()));
+    return true;
+}
+
+static bool
+MaxMallocGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.maxMallocBytesAllocated()));
+    return true;
+}
+
+static bool
+GCHighFreqGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setBoolean(cx->runtime()->gc.schedulingState.inHighFrequencyGCMode());
+    return true;
+}
+
+static bool
+GCNumberGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.gcNumber()));
+    return true;
+}
+
+static bool
+MajorGCCountGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.majorGCCount()));
+    return true;
+}
+
+static bool
+MinorGCCountGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->runtime()->gc.minorGCCount()));
+    return true;
+}
+
+static bool
+ZoneGCBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->usage.gcBytes()));
+    return true;
+}
+
+static bool
+ZoneGCTriggerBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->threshold.gcTriggerBytes()));
+    return true;
+}
+
+static bool
+ZoneGCAllocTriggerGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->threshold.allocTrigger(cx->runtime()->gc.schedulingState.inHighFrequencyGCMode())));
+    return true;
+}
+
+static bool
+ZoneMallocBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->gcMallocBytes));
+    return true;
+}
+
+static bool
+ZoneMaxMallocGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->gcMaxMallocBytes));
+    return true;
+}
+
+static bool
+ZoneGCDelayBytesGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->gcDelayBytes));
+    return true;
+}
+
+static bool
+ZoneGCHeapGrowthFactorGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(cx->zone()->threshold.gcHeapGrowthFactor());
+    return true;
+}
+
+static bool
+ZoneGCNumberGetter(JSContext *cx, unsigned argc, Value *vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+    args.rval().setNumber(double(cx->zone()->gcNumber()));
+    return true;
+}
+
+} /* namespace MemInfo */
+
+JSObject *
+NewMemoryInfoObject(JSContext *cx)
+{
+    RootedObject obj(cx, JS_NewObject(cx, nullptr));
+
+    using namespace MemInfo;
+    struct {
+        const char *name;
+        JSNative getter;
+    } getters[] = {
+        { "gcBytes", GCBytesGetter },
+        { "gcMaxBytes", GCMaxBytesGetter },
+        { "mallocBytesRemaining", MallocBytesGetter },
+        { "maxMalloc", MaxMallocGetter },
+        { "gcIsHighFrequencyMode", GCHighFreqGetter },
+        { "gcNumber", GCNumberGetter },
+        { "majorGCCount", MajorGCCountGetter },
+        { "minorGCCount", MinorGCCountGetter }
+    };
+
+    for (size_t i = 0; i < mozilla::ArrayLength(getters); i++) {
+        if (!JS_DefineProperty(cx, obj, getters[i].name, UndefinedHandleValue,
+                               JSPROP_READONLY | JSPROP_SHARED | JSPROP_ENUMERATE,
+                               getters[i].getter, nullptr))
+        {
+            return nullptr;
+        }
+    }
+
+    RootedObject zoneObj(cx, JS_NewObject(cx, nullptr));
+    if (!zoneObj)
+        return nullptr;
+
+    if (!JS_DefineProperty(cx, obj, "zone", zoneObj, JSPROP_ENUMERATE))
+        return nullptr;
+
+    struct {
+        const char *name;
+        JSNative getter;
+    } zoneGetters[] = {
+        { "gcBytes", ZoneGCBytesGetter },
+        { "gcTriggerBytes", ZoneGCTriggerBytesGetter },
+        { "gcAllocTrigger", ZoneGCAllocTriggerGetter },
+        { "mallocBytesRemaining", ZoneMallocBytesGetter },
+        { "maxMalloc", ZoneMaxMallocGetter },
+        { "delayBytes", ZoneGCDelayBytesGetter },
+        { "heapGrowthFactor", ZoneGCHeapGrowthFactorGetter },
+        { "gcNumber", ZoneGCNumberGetter }
+    };
+
+    for (size_t i = 0; i < mozilla::ArrayLength(zoneGetters); i++) {
+        if (!JS_DefineProperty(cx, zoneObj, zoneGetters[i].name, UndefinedHandleValue,
+                               JSPROP_READONLY | JSPROP_SHARED | JSPROP_ENUMERATE,
+                               zoneGetters[i].getter, nullptr))
+        {
+            return nullptr;
+        }
+    }
+
+    return obj;
+}
+
+} /* namespace gc */
+} /* namespace js */
diff --git a/js/src/jsgc.h b/js/src/jsgc.h
index 44b02ea4e4b0..86c263bb5da8 100644
--- a/js/src/jsgc.h
+++ b/js/src/jsgc.h
@@ -1395,6 +1395,9 @@ class ZoneList
     ZoneList &operator=(const ZoneList &other) = delete;
 };
 
+JSObject *
+NewMemoryStatisticsObject(JSContext *cx);
+
 } /* namespace gc */
 
 #ifdef DEBUG
diff --git a/js/src/shell/js.cpp b/js/src/shell/js.cpp
index 8ebf391de28b..f99da70bdb96 100644
--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -5643,6 +5643,22 @@ NewGlobalObject(JSContext *cx, JS::CompartmentOptions &options,
                 return nullptr;
         }
 
+        RootedObject performanceObj(cx, JS_NewObject(cx, nullptr));
+        if (!performanceObj)
+            return nullptr;
+        RootedObject mozMemoryObj(cx, JS_NewObject(cx, nullptr));
+        if (!mozMemoryObj)
+            return nullptr;
+        RootedObject gcObj(cx, gc::NewMemoryInfoObject(cx));
+        if (!gcObj)
+            return nullptr;
+        if (!JS_DefineProperty(cx, glob, "performance", performanceObj, JSPROP_ENUMERATE))
+            return nullptr;
+        if (!JS_DefineProperty(cx, performanceObj, "mozMemory", mozMemoryObj, JSPROP_ENUMERATE))
+            return nullptr;
+        if (!JS_DefineProperty(cx, mozMemoryObj, "gc", gcObj, JSPROP_ENUMERATE))
+            return nullptr;
+
         /* Initialize FakeDOMObject. */
         static const js::DOMCallbacks DOMcallbacks = {
             InstanceClassHasProtoAtDepth