diff --git a/Source/JavaScriptCore/dynbench.cpp b/Source/JavaScriptCore/dynbench.cpp
new file mode 100644
index 0000000..db359ec
--- /dev/null
+++ b/Source/JavaScriptCore/dynbench.cpp
@@ -0,0 +1,241 @@
+/*
+ * Copyright (C) 2015 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#include "config.h"
+
+#include "Identifier.h"
+#include "InitializeThreading.h"
+#include "JSCInlines.h"
+#include "JSCJSValue.h"
+#include "JSGlobalObject.h"
+#include "JSLock.h"
+#include "JSObject.h"
+#include "VM.h"
+
+using namespace JSC;
+
+namespace {
+
+StaticLock crashLock;
+const char* nameFilter;
+unsigned requestedIterationCount;
+
+#define CHECK(x) do {                                                   \
+        if (!!(x))                                                      \
+            break;                                                      \
+        crashLock.lock();                                               \
+        WTFReportAssertionFailure(__FILE__, __LINE__, WTF_PRETTY_FUNCTION, #x); \
+        CRASH();                                                        \
+    } while (false)
+
+template<typename Callback>
+NEVER_INLINE void benchmarkImpl(const char* name, unsigned iterationCount, const Callback& callback)
+{
+    if (nameFilter && !strcasestr(name, nameFilter))
+        return;
+
+    if (requestedIterationCount)
+        iterationCount = requestedIterationCount;
+    
+    double before = monotonicallyIncreasingTimeMS();
+    callback(iterationCount);
+    double after = monotonicallyIncreasingTimeMS();
+    dataLog(name, ": ", after - before, " ms.\n");
+}
+
+} // anonymous namespace
+
+int main(int argc, char** argv)
+{
+    if (argc >= 2) {
+        if (argv[1][0] == '-') {
+            dataLog("Usage: dynbench [<filter> [<iteration count>]]\n");
+            return 1;
+        }
+
+        nameFilter = argv[1];
+
+        if (argc >= 3) {
+            if (sscanf(argv[2], "%u", &requestedIterationCount) != 1) {
+                dataLog("Could not parse iteration count ", argv[2], "\n");
+                return 1;
+            }
+        }
+    }
+    
+    WTF::initializeMainThread();
+    JSC::initializeThreading();
+
+    VM* vm = &VM::create(LargeHeap).leakRef();
+    {
+        JSLockHolder locker(vm);
+
+        JSGlobalObject* globalObject =
+            JSGlobalObject::create(*vm, JSGlobalObject::createStructure(*vm, jsNull()));
+        ExecState* exec = globalObject->globalExec();
+
+        Identifier identF = Identifier::fromString(exec, "f");
+        Identifier identG = Identifier::fromString(exec, "g");
+
+        Structure* objectStructure =
+            JSFinalObject::createStructure(*vm, globalObject, globalObject->objectPrototype(), 2);
+
+        // Non-strict dynamic get by id:
+        JSValue object = JSFinalObject::create(*vm, objectStructure);
+        {
+            PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+            object.putInline(exec, identF, jsNumber(42), slot);
+        }
+        {
+            PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+            object.putInline(exec, identG, jsNumber(43), slot);
+        }
+        benchmarkImpl(
+            "Non Strict Dynamic Get By Id",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    JSValue result = object.get(exec, identF);
+                    CHECK(result == jsNumber(42));
+                    result = object.get(exec, identG);
+                    CHECK(result == jsNumber(43));
+                }
+            });
+
+        // Non-strict dynamic put by id replace:
+        object = JSFinalObject::create(*vm, objectStructure);
+        {
+            PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+            object.putInline(exec, identF, jsNumber(42), slot);
+        }
+        {
+            PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+            object.putInline(exec, identG, jsNumber(43), slot);
+        }
+        benchmarkImpl(
+            "Non Strict Dynamic Put By Id Replace",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    {
+                        PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+                        object.putInline(exec, identF, jsNumber(i), slot);
+                    }
+                    {
+                        PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+                        object.putInline(exec, identG, jsNumber(i), slot);
+                    }
+                }
+            });
+
+        // Non-strict dynamic put by id transition with object allocation:
+        benchmarkImpl(
+            "Non Strict Dynamic Allocation and Put By Id Transition",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    JSValue object = JSFinalObject::create(*vm, objectStructure);
+                    {
+                        PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+                        object.putInline(exec, identF, jsNumber(i), slot);
+                    }
+                    {
+                        PutPropertySlot slot(object, false, PutPropertySlot::PutById);
+                        object.putInline(exec, identG, jsNumber(i), slot);
+                    }
+                }
+            });
+
+        // Non-strict dynamic get by id with dynamic store context:
+        object = JSFinalObject::create(*vm, objectStructure);
+        {
+            PutPropertySlot slot(object, false);
+            object.putInline(exec, identF, jsNumber(42), slot);
+        }
+        {
+            PutPropertySlot slot(object, false);
+            object.putInline(exec, identG, jsNumber(43), slot);
+        }
+        benchmarkImpl(
+            "Non Strict Dynamic Get By Id With Dynamic Store Context",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    JSValue result = object.get(exec, identF);
+                    CHECK(result == jsNumber(42));
+                    result = object.get(exec, identG);
+                    CHECK(result == jsNumber(43));
+                }
+            });
+
+        // Non-strict dynamic put by id replace with dynamic store context:
+        object = JSFinalObject::create(*vm, objectStructure);
+        {
+            PutPropertySlot slot(object, false);
+            object.putInline(exec, identF, jsNumber(42), slot);
+        }
+        {
+            PutPropertySlot slot(object, false);
+            object.putInline(exec, identG, jsNumber(43), slot);
+        }
+        benchmarkImpl(
+            "Non Strict Dynamic Put By Id Replace With Dynamic Store Context",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    {
+                        PutPropertySlot slot(object, false);
+                        object.putInline(exec, identF, jsNumber(i), slot);
+                    }
+                    {
+                        PutPropertySlot slot(object, false);
+                        object.putInline(exec, identG, jsNumber(i), slot);
+                    }
+                }
+            });
+
+        // Non-strict dynamic put by id transition with object allocation with dynamic store context:
+        benchmarkImpl(
+            "Non Strict Dynamic Allocation and Put By Id Transition With Dynamic Store Context",
+            1000000,
+            [&] (unsigned iterationCount) {
+                for (unsigned i = iterationCount; i--;) {
+                    JSValue object = JSFinalObject::create(*vm, objectStructure);
+                    {
+                        PutPropertySlot slot(object, false);
+                        object.putInline(exec, identF, jsNumber(i), slot);
+                    }
+                    {
+                        PutPropertySlot slot(object, false);
+                        object.putInline(exec, identG, jsNumber(i), slot);
+                    }
+                }
+            });
+    }
+
+    crashLock.lock();
+    return 0;
+}
+