diff --git a/js/public/MemoryMetrics.h b/js/public/MemoryMetrics.h
index 78a83301d7f..eaa77d36b37 100644
--- a/js/public/MemoryMetrics.h
+++ b/js/public/MemoryMetrics.h
@@ -101,6 +101,7 @@ struct CompartmentStats
     int64_t gcHeapXML;
 
     int64_t objectSlots;
+    int64_t objectElements;
     int64_t stringChars;
     int64_t shapesExtraTreeTables;
     int64_t shapesExtraDictTables;
diff --git a/js/src/MemoryMetrics.cpp b/js/src/MemoryMetrics.cpp
index 1881ca13072..001078b3668 100644
--- a/js/src/MemoryMetrics.cpp
+++ b/js/src/MemoryMetrics.cpp
@@ -130,7 +130,10 @@ CellCallback(JSContext *cx, void *vdata, void *thing, JSGCTraceKind traceKind,
         } else {
             curr->gcHeapObjectsNonFunction += thingSize;
         }
-        curr->objectSlots += obj->dynamicSlotSize(data->mallocSizeOf);
+        size_t slotsSize, elementsSize;
+        obj->sizeOfExcludingThis(data->mallocSizeOf, &slotsSize, &elementsSize);
+        curr->objectSlots += slotsSize;
+        curr->objectElements += elementsSize;
         break;
     }
     case JSTRACE_STRING:
@@ -272,7 +275,8 @@ CollectCompartmentStatsForRuntime(JSRuntime *rt, IterateData *data)
         data->gcHeapArenaUnused += stats.gcHeapArenaUnused;
         data->totalObjects += stats.gcHeapObjectsNonFunction +
                               stats.gcHeapObjectsFunction +
-                              stats.objectSlots;
+                              stats.objectSlots +
+                              stats.objectElements;
         data->totalShapes  += stats.gcHeapShapesTree +
                               stats.gcHeapShapesDict +
                               stats.gcHeapShapesBase +
diff --git a/js/src/jsdbgapi.cpp b/js/src/jsdbgapi.cpp
index 9d55351ec83..48e8d81fbce 100644
--- a/js/src/jsdbgapi.cpp
+++ b/js/src/jsdbgapi.cpp
@@ -979,7 +979,7 @@ JS_SetDebugErrorHook(JSRuntime *rt, JSDebugErrorHook hook, void *closure)
 JS_PUBLIC_API(size_t)
 JS_GetObjectTotalSize(JSContext *cx, JSObject *obj)
 {
-    return obj->slotsAndStructSize();
+    return obj->computedSizeOfIncludingThis();
 }
 
 static size_t
diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
index d1212713c62..350d1d87431 100644
--- a/js/src/jsobj.cpp
+++ b/js/src/jsobj.cpp
@@ -3419,7 +3419,7 @@ JSObject::ReserveForTradeGuts(JSContext *cx, JSObject *a, JSObject *b,
      * swaps can be performed infallibly.
      */
 
-    if (a->structSize() == b->structSize())
+    if (a->sizeOfThis() == b->sizeOfThis())
         return true;
 
     /*
@@ -3512,7 +3512,7 @@ JSObject::TradeGuts(JSContext *cx, JSObject *a, JSObject *b, TradeGutsReserved &
     JS_ASSERT(a->isFunction() == b->isFunction());
 
     /* Don't try to swap a JSFunction for a plain function JSObject. */
-    JS_ASSERT_IF(a->isFunction(), a->structSize() == b->structSize());
+    JS_ASSERT_IF(a->isFunction(), a->sizeOfThis() == b->sizeOfThis());
 
     /*
      * Regexp guts are more complicated -- we would need to migrate the
@@ -3542,8 +3542,8 @@ JSObject::TradeGuts(JSContext *cx, JSObject *a, JSObject *b, TradeGutsReserved &
 #endif
 
     /* Trade the guts of the objects. */
-    const size_t size = a->structSize();
-    if (size == b->structSize()) {
+    const size_t size = a->sizeOfThis();
+    if (size == b->sizeOfThis()) {
         /*
          * If the objects are the same size, then we make no assumptions about
          * whether they have dynamically allocated slots and instead just copy
@@ -4098,7 +4098,7 @@ JSObject::growSlots(JSContext *cx, uint32_t oldCount, uint32_t newCount)
      */
     JS_ASSERT(newCount < NELEMENTS_LIMIT);
 
-    size_t oldSize = Probes::objectResizeActive() ? slotsAndStructSize() : 0;
+    size_t oldSize = Probes::objectResizeActive() ? computedSizeOfIncludingThis() : 0;
     size_t newSize = oldSize + (newCount - oldCount) * sizeof(Value);
 
     /*
@@ -4167,7 +4167,7 @@ JSObject::shrinkSlots(JSContext *cx, uint32_t oldCount, uint32_t newCount)
     if (isCall())
         return;
 
-    size_t oldSize = Probes::objectResizeActive() ? slotsAndStructSize() : 0;
+    size_t oldSize = Probes::objectResizeActive() ? computedSizeOfIncludingThis() : 0;
     size_t newSize = oldSize - (oldCount - newCount) * sizeof(Value);
 
     if (newCount == 0) {
@@ -4213,7 +4213,7 @@ JSObject::growElements(JSContext *cx, uintN newcap)
     uint32_t oldcap = getDenseArrayCapacity();
     JS_ASSERT(oldcap <= newcap);
 
-    size_t oldSize = Probes::objectResizeActive() ? slotsAndStructSize() : 0;
+    size_t oldSize = Probes::objectResizeActive() ? computedSizeOfIncludingThis() : 0;
 
     uint32_t nextsize = (oldcap <= CAPACITY_DOUBLING_MAX)
                       ? oldcap * 2
@@ -4256,7 +4256,7 @@ JSObject::growElements(JSContext *cx, uintN newcap)
     Debug_SetValueRangeToCrashOnTouch(elements + initlen, actualCapacity - initlen);
 
     if (Probes::objectResizeActive())
-        Probes::resizeObject(cx, this, oldSize, slotsAndStructSize());
+        Probes::resizeObject(cx, this, oldSize, computedSizeOfIncludingThis());
 
     return true;
 }
@@ -4269,7 +4269,7 @@ JSObject::shrinkElements(JSContext *cx, uintN newcap)
     uint32_t oldcap = getDenseArrayCapacity();
     JS_ASSERT(newcap <= oldcap);
 
-    size_t oldSize = Probes::objectResizeActive() ? slotsAndStructSize() : 0;
+    size_t oldSize = Probes::objectResizeActive() ? computedSizeOfIncludingThis() : 0;
 
     /* Don't shrink elements below the minimum capacity. */
     if (oldcap <= SLOT_CAPACITY_MIN || !hasDynamicElements())
@@ -4288,7 +4288,7 @@ JSObject::shrinkElements(JSContext *cx, uintN newcap)
     elements = newheader->elements();
 
     if (Probes::objectResizeActive())
-        Probes::resizeObject(cx, this, oldSize, slotsAndStructSize());
+        Probes::resizeObject(cx, this, oldSize, computedSizeOfIncludingThis());
 }
 
 #ifdef DEBUG
diff --git a/js/src/jsobj.h b/js/src/jsobj.h
index eff9daceb4b..0052fceceed 100644
--- a/js/src/jsobj.h
+++ b/js/src/jsobj.h
@@ -669,9 +669,12 @@ struct JSObject : js::gc::Cell
 
     inline bool hasPropertyTable() const;
 
-    inline size_t structSize() const;
-    inline size_t slotsAndStructSize() const;
-    inline size_t dynamicSlotSize(JSMallocSizeOfFun mallocSizeOf) const;
+    inline size_t sizeOfThis() const;
+    inline size_t computedSizeOfIncludingThis() const;
+
+    /* mallocSizeOf can be NULL, in which case we compute the sizes analytically */
+    inline void sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf,
+                                    size_t *slotsSize, size_t *elementsSize) const;
 
     inline size_t numFixedSlots() const;
 
diff --git a/js/src/jsobjinlines.h b/js/src/jsobjinlines.h
index f329af4c471..e36f1f6d1fa 100644
--- a/js/src/jsobjinlines.h
+++ b/js/src/jsobjinlines.h
@@ -1199,32 +1199,38 @@ JSObject::hasPropertyTable() const
 }
 
 inline size_t
-JSObject::structSize() const
+JSObject::sizeOfThis() const
 {
     return arenaHeader()->getThingSize();
 }
 
 inline size_t
-JSObject::slotsAndStructSize() const
+JSObject::computedSizeOfIncludingThis() const
 {
-    return structSize() + dynamicSlotSize(NULL);
+    size_t slotsSize, elementsSize;
+    sizeOfExcludingThis(NULL, &slotsSize, &elementsSize);
+    return sizeOfThis() + slotsSize + elementsSize;
 }
 
-inline size_t
-JSObject::dynamicSlotSize(JSMallocSizeOfFun mallocSizeOf) const
+inline void
+JSObject::sizeOfExcludingThis(JSMallocSizeOfFun mallocSizeOf,
+                              size_t *slotsSize, size_t *elementsSize) const
 {
-    size_t size = 0;
     if (hasDynamicSlots()) {
-        size_t bytes = numDynamicSlots() * sizeof(js::Value);
-        size += mallocSizeOf ? mallocSizeOf(slots, bytes) : bytes;
+        size_t computedSize = numDynamicSlots() * sizeof(js::Value);
+        *slotsSize = mallocSizeOf ? mallocSizeOf(slots, computedSize) : computedSize;
+    } else {
+        *slotsSize = 0;
     }
     if (hasDynamicElements()) {
-        size_t bytes =
+        size_t computedSize =
             (js::ObjectElements::VALUES_PER_HEADER +
              getElementsHeader()->capacity) * sizeof(js::Value);
-        size += mallocSizeOf ? mallocSizeOf(getElementsHeader(), bytes) : bytes;
+        *elementsSize =
+            mallocSizeOf ? mallocSizeOf(getElementsHeader(), computedSize) : computedSize;
+    } else {
+        *elementsSize = 0;
     }
-    return size;
 }
 
 inline JSBool
@@ -1564,7 +1570,7 @@ NewObjectCache::fill(EntryIndex entry_, Class *clasp, gc::Cell *key, gc::AllocKi
     entry->key = key;
     entry->kind = kind;
 
-    entry->nbytes = obj->structSize();
+    entry->nbytes = obj->sizeOfThis();
     js_memcpy(&entry->templateObject, obj, entry->nbytes);
 }
 
diff --git a/js/src/jsprobes.cpp b/js/src/jsprobes.cpp
index c994ff6e1af..b2629f0290f 100644
--- a/js/src/jsprobes.cpp
+++ b/js/src/jsprobes.cpp
@@ -444,7 +444,7 @@ Probes::ETWCreateObject(JSContext *cx, JSObject *obj)
 
     return EventWriteEvtObjectCreate(script_filename, lineno,
                                      ObjectClassname(obj), reinterpret_cast<uint64_t_t>(obj),
-                                     obj ? obj->slotsAndStructSize() : 0) == ERROR_SUCCESS;
+                                     obj ? obj->computedSizeOfIncludingThis() : 0) == ERROR_SUCCESS;
 }
 
 bool
diff --git a/js/xpconnect/src/XPCJSRuntime.cpp b/js/xpconnect/src/XPCJSRuntime.cpp
index 7121f2929f6..692462de1f5 100644
--- a/js/xpconnect/src/XPCJSRuntime.cpp
+++ b/js/xpconnect/src/XPCJSRuntime.cpp
@@ -1513,6 +1513,13 @@ ReportCompartmentStats(const JS::CompartmentStats &stats,
                        "'gc-heap/objects' instead." SLOP_BYTES_STRING,
                        callback, closure);
 
+    ReportMemoryBytes0(MakeMemoryReporterPath(pathPrefix, stats,
+                                              "object-elements"),
+                       nsIMemoryReporter::KIND_HEAP, stats.objectElements,
+                       "Memory allocated for the compartment's object element arrays, "
+                       "which are used to represent indexed object properties." SLOP_BYTES_STRING,
+                       callback, closure);
+
     ReportMemoryBytes0(MakeMemoryReporterPath(pathPrefix, stats,
                                               "string-chars"),
                        nsIMemoryReporter::KIND_HEAP, stats.stringChars,