diff --git a/libcutils/include/cutils/threads.h b/libcutils/include/cutils/threads.h
index 572749407..ba4846e33 100644
--- a/libcutils/include/cutils/threads.h
+++ b/libcutils/include/cutils/threads.h
@@ -29,16 +29,16 @@
 extern "C" {
 #endif
 
-/***********************************************************************/
-/***********************************************************************/
-/*****                                                             *****/
-/*****         local thread storage                                *****/
-/*****                                                             *****/
-/***********************************************************************/
-/***********************************************************************/
+//
+// Deprecated: use android::base::GetThreadId instead, which doesn't truncate on Mac/Windows.
+//
 
 extern pid_t gettid();
 
+//
+// Deprecated: use `_Thread_local` in C or `thread_local` in C++.
+//
+
 #if !defined(_WIN32)
 
 typedef struct {
@@ -70,77 +70,6 @@ extern void   thread_store_set(thread_store_t*          store,
                                void*                    value,
                                thread_store_destruct_t  destroy);
 
-/***********************************************************************/
-/***********************************************************************/
-/*****                                                             *****/
-/*****         mutexes                                             *****/
-/*****                                                             *****/
-/***********************************************************************/
-/***********************************************************************/
-
-#if !defined(_WIN32)
-
-typedef pthread_mutex_t   mutex_t;
-
-#define  MUTEX_INITIALIZER  PTHREAD_MUTEX_INITIALIZER
-
-static __inline__ void  mutex_lock(mutex_t*  lock)
-{
-    pthread_mutex_lock(lock);
-}
-static __inline__ void  mutex_unlock(mutex_t*  lock)
-{
-    pthread_mutex_unlock(lock);
-}
-static __inline__ int  mutex_init(mutex_t*  lock)
-{
-    return pthread_mutex_init(lock, NULL);
-}
-static __inline__ void mutex_destroy(mutex_t*  lock)
-{
-    pthread_mutex_destroy(lock);
-}
-
-#else // !defined(_WIN32)
-
-typedef struct {
-    int                init;
-    CRITICAL_SECTION   lock[1];
-} mutex_t;
-
-#define  MUTEX_INITIALIZER  { 0, {{ NULL, 0, 0, NULL, NULL, 0 }} }
-
-static __inline__ void  mutex_lock(mutex_t*  lock)
-{
-    if (!lock->init) {
-        lock->init = 1;
-        InitializeCriticalSection( lock->lock );
-        lock->init = 2;
-    } else while (lock->init != 2)
-        Sleep(10);
-
-    EnterCriticalSection(lock->lock);
-}
-
-static __inline__ void  mutex_unlock(mutex_t*  lock)
-{
-    LeaveCriticalSection(lock->lock);
-}
-static __inline__ int  mutex_init(mutex_t*  lock)
-{
-    InitializeCriticalSection(lock->lock);
-    lock->init = 2;
-    return 0;
-}
-static __inline__ void  mutex_destroy(mutex_t*  lock)
-{
-    if (lock->init) {
-        lock->init = 0;
-        DeleteCriticalSection(lock->lock);
-    }
-}
-#endif // !defined(_WIN32)
-
 #ifdef __cplusplus
 }
 #endif