--- libmalloc/libmalloc-67.40.1/src/malloc_internal.h
+++ libmalloc/libmalloc-53.1.1/src/malloc_internal.h
@@ -31,32 +31,30 @@
 #define MALLOC_USE_OS_LOCK_HANDOFF 1 // <rdar://problem/13807682>
 #endif
 
+#if !TARGET_IPHONE_SIMULATOR || MALLOC_USE_OS_LOCK_HANDOFF
+#define MALLOC_USE_OS_LOCK 1 // <rdar://problem/16104834> <rdar://problem/16230083>
+#endif
+
 #if MALLOC_USE_OS_LOCK_HANDOFF
 typedef os_lock_handoff_s _malloc_lock_s;
 #define _MALLOC_LOCK_INIT OS_LOCK_HANDOFF_INIT
+#elif MALLOC_USE_OS_LOCK
+typedef os_lock_spin_s _malloc_lock_s;
+#define _MALLOC_LOCK_INIT OS_LOCK_SPIN_INIT
+#else
+#include <libkern/OSAtomic.h>
+typedef OSSpinLock _malloc_lock_s;
+#define _MALLOC_LOCK_INIT OS_SPINLOCK_INIT
+#endif
 
 __attribute__((always_inline))
 static inline void
 _malloc_lock_init(_malloc_lock_s *lock) {
-	const os_lock_handoff_s _os_lock_handoff_init = OS_LOCK_HANDOFF_INIT;
-	*lock = _os_lock_handoff_init;
+	const _malloc_lock_s _malloc_lock_init = _MALLOC_LOCK_INIT;
+	*lock = _malloc_lock_init;
 }
 
-#else /* !MALLOC_USE_OS_LOCK_HANDOFF */
-
-typedef os_lock_spin_s _malloc_lock_s;
-
-#define _MALLOC_LOCK_INIT OS_LOCK_SPIN_INIT
-
-__attribute__((always_inline))
-static inline void
-_malloc_lock_init(_malloc_lock_s *lock) {
-	const os_lock_spin_s _os_lock_spin_init = OS_LOCK_SPIN_INIT;
-	*lock = _os_lock_spin_init;
-}
-
-#endif /* !MALLOC_USE_OS_LOCK_HANDOFF */
-
+#if MALLOC_USE_OS_LOCK
 __attribute__((always_inline))
 static inline void
 _malloc_lock_lock(_malloc_lock_s *lock) {
@@ -75,4 +73,27 @@
 	return os_lock_unlock(lock);
 }
 
+#else // MALLOC_USE_OS_LOCK
+
+__attribute__((always_inline))
+static inline void
+_malloc_lock_lock(_malloc_lock_s *lock) {
+	return OSSpinLockLock(lock);
+}
+
+__attribute__((always_inline))
+static inline bool
+_malloc_lock_trylock(_malloc_lock_s *lock) {
+	return OSSpinLockTry(lock);
+}
+
+__attribute__((always_inline))
+static inline void
+_malloc_lock_unlock(_malloc_lock_s *lock) {
+	return OSSpinLockUnlock(lock);
+}
+
+#endif // MALLOC_USE_OS_LOCK
+
+
 #endif // __MALLOC_INTERNAL_H