diff --git a/js/src/builtin/RegExp.cpp b/js/src/builtin/RegExp.cpp
index 2f3ea0f25ed..758c39ed606 100644
--- a/js/src/builtin/RegExp.cpp
+++ b/js/src/builtin/RegExp.cpp
@@ -18,42 +18,19 @@ using namespace js::types;
 
 using mozilla::ArrayLength;
 
-class RegExpMatchBuilder
+static inline bool
+DefinePropertyHelper(JSContext *cx, HandleObject obj, Handle<PropertyName*> name, HandleValue v)
 {
-    JSContext   * const cx;
-    RootedObject array;
-
-    bool setProperty(Handle<PropertyName*> name, HandleValue v) {
-        return !!baseops::DefineProperty(cx, array, name, v,
-                                         JS_PropertyStub, JS_StrictPropertyStub, JSPROP_ENUMERATE);
-    }
-
-  public:
-    RegExpMatchBuilder(JSContext *cx, HandleObject array) : cx(cx), array(cx, array) {}
-
-    bool append(uint32_t index, HandleValue v) {
-        JS_ASSERT(!array->getOps()->getElement);
-        return !!baseops::DefineElement(cx, array, index, v, JS_PropertyStub, JS_StrictPropertyStub,
-                                        JSPROP_ENUMERATE);
-    }
-
-    bool setIndex(int index) {
-        RootedValue value(cx, Int32Value(index));
-        return setProperty(cx->names().index, value);
-    }
-
-    bool setInput(HandleString str) {
-        JS_ASSERT(str);
-        RootedValue value(cx, StringValue(str));
-        return setProperty(cx->names().input, value);
-    }
-};
+    return !!baseops::DefineProperty(cx, obj, name, v,
+                                     JS_PropertyStub, JS_StrictPropertyStub, JSPROP_ENUMERATE);
+}
 
 bool
 js::CreateRegExpMatchResult(JSContext *cx, HandleString input_, const jschar *chars, size_t length,
                             MatchPairs &matches, MutableHandleValue rval)
 {
     RootedString input(cx, input_);
+    RootedValue undefinedValue(cx, UndefinedValue());
 
     /*
      * Create the (slow) result array for a match.
@@ -64,39 +41,47 @@ js::CreateRegExpMatchResult(JSContext *cx, HandleString input_, const jschar *ch
      *  input:          input string
      *  index:          start index for the match
      */
-    RootedObject array(cx, NewDenseEmptyArray(cx));
-    if (!array)
-        return false;
-
     if (!input) {
         input = js_NewStringCopyN<CanGC>(cx, chars, length);
         if (!input)
             return false;
     }
 
-    RegExpMatchBuilder builder(cx, array);
-    RootedValue undefinedValue(cx, UndefinedValue());
-
     size_t numPairs = matches.length();
     JS_ASSERT(numPairs > 0);
 
+    AutoValueVector elements(cx);
+    if (!elements.reserve(numPairs))
+        return false;
+
+    /* Accumulate a Value for each pair, in a rooted vector. */
     for (size_t i = 0; i < numPairs; ++i) {
         const MatchPair &pair = matches[i];
 
-        RootedString captured(cx);
         if (pair.isUndefined()) {
             JS_ASSERT(i != 0); /* Since we had a match, first pair must be present. */
-            if (!builder.append(i, undefinedValue))
-                return false;
+            elements.infallibleAppend(undefinedValue);
         } else {
-            captured = js_NewDependentString(cx, input, pair.start, pair.length());
-            RootedValue value(cx, StringValue(captured));
-            if (!captured || !builder.append(i, value))
+            JSLinearString *str = js_NewDependentString(cx, input, pair.start, pair.length());
+            if (!str)
                 return false;
+            elements.infallibleAppend(StringValue(str));
         }
     }
 
-    if (!builder.setIndex(matches[0].start) || !builder.setInput(input))
+    /* Copy the rooted vector into the array object. */
+    RootedObject array(cx, NewDenseCopiedArray(cx, elements.length(), elements.begin()));
+    if (!array)
+        return false;
+
+    /* Set the |index| property. */
+    RootedValue index(cx, Int32Value(matches[0].start));
+    if (!DefinePropertyHelper(cx, array, cx->names().index, index))
+        return false;
+
+    /* Set the |input| property. */
+    RootedValue inputVal(cx, StringValue(input));
+    if (!DefinePropertyHelper(cx, array, cx->names().input, inputVal))
         return false;
 
     rval.setObject(*array);