new file mode 100644
--- /dev/null
+++ b/js/src/jit-test/tests/cacheir/nukedCCW.js
@@ -0,0 +1,23 @@
+var wrapper = evaluate("({a: 15, b: {c: 42}})", {global: newGlobal({sameZoneAs: this})});
+
+function test() {
+    var i, error;
+    try {
+        for (i = 0; i < 150; i++) {
+            assertEq(wrapper.b.c, 42);
+            assertEq(wrapper.a, 15);
+
+            if (i == 142) {
+                // Next access to wrapper.b should throw.
+                nukeCCW(wrapper);
+            }
+        }
+    } catch (e) {
+        error = e;
+    }
+
+    assertEq(error.message.includes("dead object"), true);
+    assertEq(i, 143);
+}
+
+test();

--- a/js/src/shell/js.cpp
+++ b/js/src/shell/js.cpp
@@ -5033,16 +5033,34 @@ NewGlobal(JSContext* cx, unsigned argc, 
     if (!JS_WrapObject(cx, &global))
         return false;
 
     args.rval().setObject(*global);
     return true;
 }
 
 static bool
+NukeCCW(JSContext* cx, unsigned argc, Value* vp)
+{
+    CallArgs args = CallArgsFromVp(argc, vp);
+
+    if (args.length() != 1 || !args[0].isObject() ||
+        !IsCrossCompartmentWrapper(&args[0].toObject()))
+    {
+        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
+                                  "nukeCCW");
+        return false;
+    }
+
+    NukeCrossCompartmentWrapper(cx, &args[0].toObject());
+    args.rval().setUndefined();
+    return true;
+}
+
+static bool
 GetMaxArgs(JSContext* cx, unsigned argc, Value* vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
     args.rval().setInt32(ARGS_LENGTH_MAX);
     return true;
 }
 
 static bool
@@ -6361,16 +6379,20 @@ static const JSFunctionSpecWithHelp shel
 "         integer that fits in 32 bits; use that as the new compartment's\n"
 "         principal. Shell principals are toys, meant only for testing; one\n"
 "         shell principal subsumes another if its set bits are a superset of\n"
 "         the other's. Thus, a principal of 0 subsumes nothing, while a\n"
 "         principals of ~0 subsumes all other principals. The absence of a\n"
 "         principal is treated as if its bits were 0xffff, for subsumption\n"
 "         purposes. If this property is omitted, supply no principal."),
 
+    JS_FN_HELP("nukeCCW", NukeCCW, 1, 0,
+"nukeCCW(wrapper)",
+"  Nuke a CrossCompartmentWrapper, which turns it into a DeadProxyObject."),
+
     JS_FN_HELP("createMappedArrayBuffer", CreateMappedArrayBuffer, 1, 0,
 "createMappedArrayBuffer(filename, [offset, [size]])",
 "  Create an array buffer that mmaps the given file."),
 
     JS_FN_HELP("addPromiseReactions", AddPromiseReactions, 3, 0,
 "addPromiseReactions(promise, onResolve, onReject)",
 "  Calls the JS::AddPromiseReactions JSAPI function with the given arguments."),