diff --git a/content/canvas/src/CanvasRenderingContext2D.cpp b/content/canvas/src/CanvasRenderingContext2D.cpp
index 8419a0ed8e5..32d6970f4c4 100644
--- a/content/canvas/src/CanvasRenderingContext2D.cpp
+++ b/content/canvas/src/CanvasRenderingContext2D.cpp
@@ -1254,7 +1254,7 @@ CanvasRenderingContext2D::GetMozCurrentTransformInverse(JSContext* cx,
 
 void
 CanvasRenderingContext2D::SetStyleFromJSValue(JSContext* cx,
-                                              JS::Value& value,
+                                              JS::Handle<JS::Value> value,
                                               Style whichStyle)
 {
   if (value.isString()) {
@@ -1269,9 +1269,10 @@ CanvasRenderingContext2D::SetStyleFromJSValue(JSContext* cx,
     nsCOMPtr<nsISupports> holder;
 
     CanvasGradient* gradient;
+    JS::Rooted<JS::Value> rootedVal(cx, value);
     nsresult rv = xpc_qsUnwrapArg<CanvasGradient>(cx, value, &gradient,
                                                   static_cast<nsISupports**>(getter_AddRefs(holder)),
-                                                  &value);
+                                                  rootedVal.address());
     if (NS_SUCCEEDED(rv)) {
       SetStyleFromGradient(gradient, whichStyle);
       return;
@@ -1280,7 +1281,7 @@ CanvasRenderingContext2D::SetStyleFromJSValue(JSContext* cx,
     CanvasPattern* pattern;
     rv = xpc_qsUnwrapArg<CanvasPattern>(cx, value, &pattern,
                                         static_cast<nsISupports**>(getter_AddRefs(holder)),
-                                        &value);
+                                        rootedVal.address());
     if (NS_SUCCEEDED(rv)) {
       SetStyleFromPattern(pattern, whichStyle);
       return;
diff --git a/content/canvas/src/CanvasRenderingContext2D.h b/content/canvas/src/CanvasRenderingContext2D.h
index 7ef8f4640aa..ad9f71cfa7e 100644
--- a/content/canvas/src/CanvasRenderingContext2D.h
+++ b/content/canvas/src/CanvasRenderingContext2D.h
@@ -92,14 +92,14 @@ public:
                                    mozilla::ErrorResult& error);
   JS::Value GetStrokeStyle(JSContext* cx, mozilla::ErrorResult& error);
 
-  void SetStrokeStyle(JSContext* cx, JS::Value& value)
+  void SetStrokeStyle(JSContext* cx, JS::Handle<JS::Value> value)
   {
     SetStyleFromJSValue(cx, value, STYLE_STROKE);
   }
 
   JS::Value GetFillStyle(JSContext* cx, mozilla::ErrorResult& error);
 
-  void SetFillStyle(JSContext* cx, JS::Value& value)
+  void SetFillStyle(JSContext* cx, JS::Handle<JS::Value> value)
   {
     SetStyleFromJSValue(cx, value, STYLE_FILL);
   }
@@ -471,7 +471,8 @@ protected:
   static mozilla::gfx::DrawTarget* sErrorTarget;
 
   // Some helpers.  Doesn't modify a color on failure.
-  void SetStyleFromJSValue(JSContext* cx, JS::Value& value, Style whichStyle);
+  void SetStyleFromJSValue(JSContext* cx, JS::Handle<JS::Value> value,
+			   Style whichStyle);
   void SetStyleFromString(const nsAString& str, Style whichStyle);
 
   void SetStyleFromGradient(CanvasGradient *gradient, Style whichStyle)
diff --git a/content/events/src/nsDOMMessageEvent.h b/content/events/src/nsDOMMessageEvent.h
index bbdcc6ee631..72c17bf663f 100644
--- a/content/events/src/nsDOMMessageEvent.h
+++ b/content/events/src/nsDOMMessageEvent.h
@@ -54,7 +54,7 @@ public:
                         const nsAString& aType,
                         bool aCanBubble,
                         bool aCancelable,
-                        JS::Value& aData,
+                        JS::Value aData,
                         const nsAString& aOrigin,
                         const nsAString& aLastEventId,
                         nsIDOMWindow* aSource,
diff --git a/content/html/content/public/HTMLCanvasElement.h b/content/html/content/public/HTMLCanvasElement.h
index 0a7ee639de3..fab95d8b100 100644
--- a/content/html/content/public/HTMLCanvasElement.h
+++ b/content/html/content/public/HTMLCanvasElement.h
@@ -92,7 +92,7 @@ public:
   }
   already_AddRefed<nsISupports>
   GetContext(JSContext* aCx, const nsAString& aContextId,
-             const Optional<JS::Value>& aContextOptions, ErrorResult& aRv)
+             const Optional<LazyRootedValue>& aContextOptions, ErrorResult& aRv)
   {
     JS::Value contextOptions = aContextOptions.WasPassed()
                              ? aContextOptions.Value()
@@ -102,7 +102,7 @@ public:
     return context.forget();
   }
   void ToDataURL(JSContext* aCx, const nsAString& aType,
-                 const Optional<JS::Value>& aParams, nsAString& aDataURL,
+                 const Optional<LazyRootedValue>& aParams, nsAString& aDataURL,
                  ErrorResult& aRv)
   {
     JS::Value params = aParams.WasPassed()
diff --git a/dom/bindings/BindingDeclarations.h b/dom/bindings/BindingDeclarations.h
index af141cfd826..1ff48fe36ca 100644
--- a/dom/bindings/BindingDeclarations.h
+++ b/dom/bindings/BindingDeclarations.h
@@ -515,6 +515,34 @@ public:
   }
 };
 
+class LazyRootedValue : public Maybe<JS::Rooted<JS::Value> >
+{
+public:
+  operator JS::Value() const
+  {
+    // Assert if we're empty, on purpose
+    return ref();
+  }
+
+  operator JS::Rooted<JS::Value>& ()
+  {
+    // Assert if we're empty, on purpose
+    return ref();
+  }
+
+  operator JS::Handle<JS::Value>()
+  {
+    // Assert if we're empty, on purpose
+    return ref();
+  }
+
+  JS::Value* operator&()
+  {
+    // Assert if we're empty, on purpose
+    return ref().address();
+  }
+};
+
 } // namespace dom
 } // namespace mozilla
 
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
index c1c148fae1a..57f259f4db6 100644
--- a/dom/bindings/Codegen.py
+++ b/dom/bindings/Codegen.py
@@ -3222,20 +3222,19 @@ for (uint32_t i = 0; i < length; ++i) {
     if type.isAny():
         assert not isEnforceRange and not isClamp
 
-        if isMember == "Dictionary":
-            declType = "RootedJSValue"
-            templateBody = ("if (!${declName}.SetValue(cx, ${val})) {\n"
-                            "  return false;\n"
-                            "}")
-            nullHandling = "${declName}.SetValue(nullptr, JS::NullValue())"
-        elif isMember and isMember != "Variadic":
-            # Variadic arguments are rooted by being in argv
+        if isMember == "Dictionary" or not isMember:
+            declType = "LazyRootedValue"
+            templateBody = "${declName}.construct(cx, ${val});"
+            nullHandling = "${declName}.construct(cx, JS::NullValue());"
+        elif isMember != "Variadic":
             raise TypeError("Can't handle sequence member 'any'; need to sort "
                             "out rooting issues")
         else:
+            # Variadic arguments are rooted by being in argv
             declType = "JS::Value"
             templateBody = "${declName} = ${val};"
             nullHandling = "${declName} = JS::NullValue()"
+
         templateBody = handleDefaultNull(templateBody, nullHandling)
         return (templateBody, CGGeneric(declType), None, isOptional)
 
@@ -8115,7 +8114,7 @@ class CGNativeMember(ClassMethod):
             args.insert(0, Argument("const %s&" % globalObjectType, "global"))
         return args
 
-    def doGetArgType(self, type, optional, isMember):
+    def doGetArgType(self, type, optional, variadic, isMember):
         """
         The main work of getArgType.  Returns a string type decl, whether this
         is a const ref, as well as whether the type should be wrapped in
@@ -8204,7 +8203,12 @@ class CGNativeMember(ClassMethod):
             return declType % name, False, False
 
         if type.isAny():
-            return "JS::Value", False, False
+            # Don't do the rooting stuff for variadics for now
+            if optional and not variadic:
+                declType = "LazyRootedValue"
+            else:
+                declType = "JS::Value"
+            return declType, False, False
 
         if type.isObject():
             if optional:
@@ -8235,7 +8239,7 @@ class CGNativeMember(ClassMethod):
         Get the type of an argument declaration.  Returns the type CGThing, and
         whether this should be a const ref.
         """
-        (decl, ref, handleNullable) = self.doGetArgType(type, optional,
+        (decl, ref, handleNullable) = self.doGetArgType(type, optional, variadic,
                                                         isMember or variadic)
         decl = CGGeneric(decl)
         if handleNullable and type.nullable():
diff --git a/dom/bindings/test/TestBindingHeader.h b/dom/bindings/test/TestBindingHeader.h
index 22719574655..97d2f5d7a8e 100644
--- a/dom/bindings/test/TestBindingHeader.h
+++ b/dom/bindings/test/TestBindingHeader.h
@@ -140,7 +140,7 @@ public:
                                         JSObject&,
                                         JSObject*,
                                         const Sequence<Dict>&,
-                                        const Optional<JS::Value>&,
+                                        const Optional<LazyRootedValue>&,
                                         const Optional<NonNullLazyRootedObject>&,
                                         const Optional<LazyRootedObject>&,
                                         ErrorResult&);
@@ -429,7 +429,7 @@ public:
 
   // Any types
   void PassAny(JSContext*, JS::Value);
-  void PassOptionalAny(JSContext*, const Optional<JS::Value>&);
+  void PassOptionalAny(JSContext*, const Optional<LazyRootedValue>&);
   void PassAnyDefaultNull(JSContext*, JS::Value);
   JS::Value ReceiveAny(JSContext*);