diff --git a/libc/bionic/__cxa_guard.cpp b/libc/bionic/__cxa_guard.cpp
index 5b34b58..97284d5 100644
--- a/libc/bionic/__cxa_guard.cpp
+++ b/libc/bionic/__cxa_guard.cpp
@@ -109,7 +109,7 @@
       }
     }
 
-    __futex_wait_ex(&gv->state, false, CONSTRUCTION_UNDERWAY_WITH_WAITER, NULL);
+    __futex_wait_ex(&gv->state, false, CONSTRUCTION_UNDERWAY_WITH_WAITER, false, nullptr);
     old_value = atomic_load_explicit(&gv->state, memory_order_relaxed);
   }
 }
diff --git a/libc/bionic/bionic_time_conversions.cpp b/libc/bionic/bionic_time_conversions.cpp
index 75e8d49..f3ca46a 100644
--- a/libc/bionic/bionic_time_conversions.cpp
+++ b/libc/bionic/bionic_time_conversions.cpp
@@ -52,18 +52,12 @@
   tv.tv_usec = ts.tv_nsec / 1000;
 }
 
-// Initializes 'ts' with the difference between 'abs_ts' and the current time
-// according to 'clock'. Returns false if abstime already expired, true otherwise.
-bool timespec_from_absolute_timespec(timespec& ts, const timespec& abs_ts, clockid_t clock) {
-  clock_gettime(clock, &ts);
-  ts.tv_sec = abs_ts.tv_sec - ts.tv_sec;
-  ts.tv_nsec = abs_ts.tv_nsec - ts.tv_nsec;
-  if (ts.tv_nsec < 0) {
-    ts.tv_sec--;
-    ts.tv_nsec += NS_PER_S;
+void absolute_timespec_from_timespec(timespec& abs_ts, const timespec& ts, clockid_t clock) {
+  clock_gettime(clock, &abs_ts);
+  abs_ts.tv_sec += ts.tv_sec;
+  abs_ts.tv_nsec += ts.tv_nsec;
+  if (abs_ts.tv_nsec >= NS_PER_S) {
+    abs_ts.tv_nsec -= NS_PER_S;
+    abs_ts.tv_sec++;
   }
-  if (ts.tv_nsec < 0 || ts.tv_sec < 0) {
-    return false;
-  }
-  return true;
 }
diff --git a/libc/bionic/pthread_barrier.cpp b/libc/bionic/pthread_barrier.cpp
index 3227daf..1bcd12a 100644
--- a/libc/bionic/pthread_barrier.cpp
+++ b/libc/bionic/pthread_barrier.cpp
@@ -118,7 +118,7 @@
   // threads have left the barrier. Use acquire operation here to synchronize with
   // the last thread leaving the previous cycle, so we can read correct wait_count below.
   while(atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
-    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
+    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, false, nullptr);
   }
 
   uint32_t prev_wait_count = atomic_load_explicit(&barrier->wait_count, memory_order_relaxed);
@@ -152,7 +152,7 @@
     // Use acquire operation here to synchronize between the last thread entering the
     // barrier with all threads leaving the barrier.
     while (atomic_load_explicit(&barrier->state, memory_order_acquire) == WAIT) {
-      __futex_wait_ex(&barrier->state, barrier->pshared, WAIT, nullptr);
+      __futex_wait_ex(&barrier->state, barrier->pshared, WAIT, false, nullptr);
     }
   }
   // Use release operation here to make it not reordered with previous operations.
@@ -173,7 +173,7 @@
   // Use acquire operation here to synchronize with the last thread leaving the barrier.
   // So we can read correct wait_count below.
   while (atomic_load_explicit(&barrier->state, memory_order_acquire) == RELEASE) {
-    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, nullptr);
+    __futex_wait_ex(&barrier->state, barrier->pshared, RELEASE, false, nullptr);
   }
   if (atomic_load_explicit(&barrier->wait_count, memory_order_relaxed) != 0) {
     return EBUSY;
diff --git a/libc/bionic/pthread_cond.cpp b/libc/bionic/pthread_cond.cpp
index 4a69da5..adbce07 100644
--- a/libc/bionic/pthread_cond.cpp
+++ b/libc/bionic/pthread_cond.cpp
@@ -111,8 +111,8 @@
     return COND_IS_SHARED(atomic_load_explicit(&state, memory_order_relaxed));
   }
 
-  int get_clock() {
-    return COND_GET_CLOCK(atomic_load_explicit(&state, memory_order_relaxed));
+  bool use_realtime_clock() {
+    return COND_GET_CLOCK(atomic_load_explicit(&state, memory_order_relaxed)) == CLOCK_REALTIME;
   }
 
 #if defined(__LP64__)
@@ -170,12 +170,17 @@
   return 0;
 }
 
-static int __pthread_cond_timedwait_relative(pthread_cond_internal_t* cond, pthread_mutex_t* mutex,
-                                             const timespec* rel_timeout_or_null) {
-  unsigned int old_state = atomic_load_explicit(&cond->state, memory_order_relaxed);
+static int __pthread_cond_timedwait(pthread_cond_internal_t* cond, pthread_mutex_t* mutex,
+                                    bool use_realtime_clock, const timespec* abs_timeout_or_null) {
+  int result = check_timespec(abs_timeout_or_null);
+  if (result != 0) {
+    return result;
+  }
 
+  unsigned int old_state = atomic_load_explicit(&cond->state, memory_order_relaxed);
   pthread_mutex_unlock(mutex);
-  int status = __futex_wait_ex(&cond->state, cond->process_shared(), old_state, rel_timeout_or_null);
+  int status = __futex_wait_ex(&cond->state, cond->process_shared(), old_state,
+                               use_realtime_clock, abs_timeout_or_null);
   pthread_mutex_lock(mutex);
 
   if (status == -ETIMEDOUT) {
@@ -184,21 +189,6 @@
   return 0;
 }
 
-static int __pthread_cond_timedwait(pthread_cond_internal_t* cond, pthread_mutex_t* mutex,
-                                    const timespec* abs_timeout_or_null, clockid_t clock) {
-  timespec ts;
-  timespec* rel_timeout = NULL;
-
-  if (abs_timeout_or_null != NULL) {
-    rel_timeout = &ts;
-    if (!timespec_from_absolute_timespec(*rel_timeout, *abs_timeout_or_null, clock)) {
-      return ETIMEDOUT;
-    }
-  }
-
-  return __pthread_cond_timedwait_relative(cond, mutex, rel_timeout);
-}
-
 int pthread_cond_broadcast(pthread_cond_t* cond_interface) {
   return __pthread_cond_pulse(__get_internal_cond(cond_interface), INT_MAX);
 }
@@ -209,14 +199,14 @@
 
 int pthread_cond_wait(pthread_cond_t* cond_interface, pthread_mutex_t* mutex) {
   pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
-  return __pthread_cond_timedwait(cond, mutex, NULL, cond->get_clock());
+  return __pthread_cond_timedwait(cond, mutex, false, nullptr);
 }
 
 int pthread_cond_timedwait(pthread_cond_t *cond_interface, pthread_mutex_t * mutex,
                            const timespec *abstime) {
 
   pthread_cond_internal_t* cond = __get_internal_cond(cond_interface);
-  return __pthread_cond_timedwait(cond, mutex, abstime, cond->get_clock());
+  return __pthread_cond_timedwait(cond, mutex, cond->use_realtime_clock(), abstime);
 }
 
 #if !defined(__LP64__)
@@ -225,8 +215,7 @@
                                                 pthread_mutex_t* mutex,
                                                 const timespec* abs_timeout) {
 
-  return __pthread_cond_timedwait(__get_internal_cond(cond_interface), mutex, abs_timeout,
-                                  CLOCK_MONOTONIC);
+  return __pthread_cond_timedwait(__get_internal_cond(cond_interface), mutex, false, abs_timeout);
 }
 
 extern "C" int pthread_cond_timedwait_monotonic_np(pthread_cond_t* cond_interface,
@@ -238,8 +227,13 @@
 extern "C" int pthread_cond_timedwait_relative_np(pthread_cond_t* cond_interface,
                                                   pthread_mutex_t* mutex,
                                                   const timespec* rel_timeout) {
-
-  return __pthread_cond_timedwait_relative(__get_internal_cond(cond_interface), mutex, rel_timeout);
+  timespec ts;
+  timespec* abs_timeout = nullptr;
+  if (rel_timeout != nullptr) {
+    absolute_timespec_from_timespec(ts, *rel_timeout, CLOCK_REALTIME);
+    abs_timeout = &ts;
+  }
+  return __pthread_cond_timedwait(__get_internal_cond(cond_interface), mutex, true, abs_timeout);
 }
 
 extern "C" int pthread_cond_timeout_np(pthread_cond_t* cond_interface,
diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index 851fc3d..23dc3b0 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -296,11 +296,15 @@
  */
 static inline __always_inline int __pthread_normal_mutex_lock(pthread_mutex_internal_t* mutex,
                                                               uint16_t shared,
-                                                              const timespec* abs_timeout_or_null,
-                                                              clockid_t clock) {
+                                                              bool use_realtime_clock,
+                                                              const timespec* abs_timeout_or_null) {
     if (__predict_true(__pthread_normal_mutex_trylock(mutex, shared) == 0)) {
         return 0;
     }
+    int result = check_timespec(abs_timeout_or_null);
+    if (result != 0) {
+        return result;
+    }
 
     ScopedTrace trace("Contending for pthread mutex");
 
@@ -317,15 +321,8 @@
     // made by other threads visible to the current CPU.
     while (atomic_exchange_explicit(&mutex->state, locked_contended,
                                     memory_order_acquire) != unlocked) {
-        timespec ts;
-        timespec* rel_timeout = NULL;
-        if (abs_timeout_or_null != NULL) {
-            rel_timeout = &ts;
-            if (!timespec_from_absolute_timespec(*rel_timeout, *abs_timeout_or_null, clock)) {
-                return ETIMEDOUT;
-            }
-        }
-        if (__futex_wait_ex(&mutex->state, shared, locked_contended, rel_timeout) == -ETIMEDOUT) {
+        if (__futex_wait_ex(&mutex->state, shared, locked_contended, use_realtime_clock,
+                            abs_timeout_or_null) == -ETIMEDOUT) {
             return ETIMEDOUT;
         }
     }
@@ -396,14 +393,15 @@
                                                       pthread_mutex_internal_t* mutex,
                                                       uint16_t shared,
                                                       uint16_t old_state,
-                                                      const timespec* rel_timeout) {
+                                                      bool use_realtime_clock,
+                                                      const timespec* abs_timeout) {
 // __futex_wait always waits on a 32-bit value. But state is 16-bit. For a normal mutex, the owner_tid
 // field in mutex is not used. On 64-bit devices, the __pad field in mutex is not used.
 // But when a recursive or errorcheck mutex is used on 32-bit devices, we need to add the
 // owner_tid value in the value argument for __futex_wait, otherwise we may always get EAGAIN error.
 
 #if defined(__LP64__)
-  return __futex_wait_ex(&mutex->state, shared, old_state, rel_timeout);
+  return __futex_wait_ex(&mutex->state, shared, old_state, use_realtime_clock, abs_timeout);
 
 #else
   // This implementation works only when the layout of pthread_mutex_internal_t matches below expectation.
@@ -412,19 +410,21 @@
   static_assert(offsetof(pthread_mutex_internal_t, owner_tid) == 2, "");
 
   uint32_t owner_tid = atomic_load_explicit(&mutex->owner_tid, memory_order_relaxed);
-  return __futex_wait_ex(&mutex->state, shared, (owner_tid << 16) | old_state, rel_timeout);
+  return __futex_wait_ex(&mutex->state, shared, (owner_tid << 16) | old_state,
+                         use_realtime_clock, abs_timeout);
 #endif
 }
 
 static int __pthread_mutex_lock_with_timeout(pthread_mutex_internal_t* mutex,
-                                           const timespec* abs_timeout_or_null, clockid_t clock) {
+                                             bool use_realtime_clock,
+                                             const timespec* abs_timeout_or_null) {
     uint16_t old_state = atomic_load_explicit(&mutex->state, memory_order_relaxed);
     uint16_t mtype = (old_state & MUTEX_TYPE_MASK);
     uint16_t shared = (old_state & MUTEX_SHARED_MASK);
 
     // Handle common case first.
     if ( __predict_true(mtype == MUTEX_TYPE_BITS_NORMAL) ) {
-        return __pthread_normal_mutex_lock(mutex, shared, abs_timeout_or_null, clock);
+        return __pthread_normal_mutex_lock(mutex, shared, use_realtime_clock, abs_timeout_or_null);
     }
 
     // Do we already own this recursive or error-check mutex?
@@ -484,16 +484,13 @@
             old_state = new_state;
         }
 
-        // We are in locked_contended state, sleep until someone wakes us up.
-        timespec ts;
-        timespec* rel_timeout = NULL;
-        if (abs_timeout_or_null != NULL) {
-            rel_timeout = &ts;
-            if (!timespec_from_absolute_timespec(*rel_timeout, *abs_timeout_or_null, clock)) {
-                return ETIMEDOUT;
-            }
+        int result = check_timespec(abs_timeout_or_null);
+        if (result != 0) {
+            return result;
         }
-        if (__recursive_or_errorcheck_mutex_wait(mutex, shared, old_state, rel_timeout) == -ETIMEDOUT) {
+        // We are in locked_contended state, sleep until someone wakes us up.
+        if (__recursive_or_errorcheck_mutex_wait(mutex, shared, old_state, use_realtime_clock,
+                                                 abs_timeout_or_null) == -ETIMEDOUT) {
             return ETIMEDOUT;
         }
         old_state = atomic_load_explicit(&mutex->state, memory_order_relaxed);
@@ -518,7 +515,7 @@
         return 0;
       }
     }
-    return __pthread_mutex_lock_with_timeout(mutex, NULL, 0);
+    return __pthread_mutex_lock_with_timeout(mutex, false, nullptr);
 }
 
 int pthread_mutex_unlock(pthread_mutex_t* mutex_interface) {
@@ -613,17 +610,12 @@
 
 #if !defined(__LP64__)
 extern "C" int pthread_mutex_lock_timeout_np(pthread_mutex_t* mutex_interface, unsigned ms) {
+    timespec ts;
+    timespec_from_ms(ts, ms);
     timespec abs_timeout;
-    clock_gettime(CLOCK_MONOTONIC, &abs_timeout);
-    abs_timeout.tv_sec  += ms / 1000;
-    abs_timeout.tv_nsec += (ms % 1000) * 1000000;
-    if (abs_timeout.tv_nsec >= NS_PER_S) {
-        abs_timeout.tv_sec++;
-        abs_timeout.tv_nsec -= NS_PER_S;
-    }
-
+    absolute_timespec_from_timespec(abs_timeout, ts, CLOCK_MONOTONIC);
     int error = __pthread_mutex_lock_with_timeout(__get_internal_mutex(mutex_interface),
-                                                  &abs_timeout, CLOCK_MONOTONIC);
+                                                  false, &abs_timeout);
     if (error == ETIMEDOUT) {
         error = EBUSY;
     }
@@ -633,7 +625,7 @@
 
 int pthread_mutex_timedlock(pthread_mutex_t* mutex_interface, const timespec* abs_timeout) {
     return __pthread_mutex_lock_with_timeout(__get_internal_mutex(mutex_interface),
-                                             abs_timeout, CLOCK_REALTIME);
+                                             true, abs_timeout);
 }
 
 int pthread_mutex_destroy(pthread_mutex_t* mutex_interface) {
diff --git a/libc/bionic/pthread_once.cpp b/libc/bionic/pthread_once.cpp
index 7688a23..f48eadc 100644
--- a/libc/bionic/pthread_once.cpp
+++ b/libc/bionic/pthread_once.cpp
@@ -79,7 +79,7 @@
     }
 
     // The initialization is underway, wait for its finish.
-    __futex_wait_ex(once_control_ptr, 0, old_value, NULL);
+    __futex_wait_ex(once_control_ptr, 0, old_value, false, nullptr);
     old_value = atomic_load_explicit(once_control_ptr, memory_order_acquire);
   }
 }
diff --git a/libc/bionic/pthread_rwlock.cpp b/libc/bionic/pthread_rwlock.cpp
index 934210e..b1c48c8 100644
--- a/libc/bionic/pthread_rwlock.cpp
+++ b/libc/bionic/pthread_rwlock.cpp
@@ -294,9 +294,13 @@
   }
 
   while (true) {
-    int ret = __pthread_rwlock_tryrdlock(rwlock);
-    if (ret == 0 || ret == EAGAIN) {
-      return ret;
+    int result = __pthread_rwlock_tryrdlock(rwlock);
+    if (result == 0 || result == EAGAIN) {
+      return result;
+    }
+    result = check_timespec(abs_timeout_or_null);
+    if (result != 0) {
+      return result;
     }
 
     int old_state = atomic_load_explicit(&rwlock->state, memory_order_relaxed);
@@ -304,16 +308,6 @@
       continue;
     }
 
-    timespec ts;
-    timespec* rel_timeout = NULL;
-
-    if (abs_timeout_or_null != NULL) {
-      rel_timeout = &ts;
-      if (!timespec_from_absolute_timespec(*rel_timeout, *abs_timeout_or_null, CLOCK_REALTIME)) {
-        return ETIMEDOUT;
-      }
-    }
-
     rwlock->pending_lock.lock();
     rwlock->pending_reader_count++;
 
@@ -327,10 +321,10 @@
     int old_serial = rwlock->pending_reader_wakeup_serial;
     rwlock->pending_lock.unlock();
 
-    int futex_ret = 0;
+    int futex_result = 0;
     if (!__can_acquire_read_lock(old_state, rwlock->writer_nonrecursive_preferred)) {
-      futex_ret = __futex_wait_ex(&rwlock->pending_reader_wakeup_serial, rwlock->pshared,
-                                  old_serial, rel_timeout);
+      futex_result = __futex_wait_ex(&rwlock->pending_reader_wakeup_serial, rwlock->pshared,
+                                  old_serial, true, abs_timeout_or_null);
     }
 
     rwlock->pending_lock.lock();
@@ -341,7 +335,7 @@
     }
     rwlock->pending_lock.unlock();
 
-    if (futex_ret == -ETIMEDOUT) {
+    if (futex_result == -ETIMEDOUT) {
       return ETIMEDOUT;
     }
   }
@@ -372,9 +366,13 @@
     return EDEADLK;
   }
   while (true) {
-    int ret = __pthread_rwlock_trywrlock(rwlock);
-    if (ret == 0) {
-      return ret;
+    int result = __pthread_rwlock_trywrlock(rwlock);
+    if (result == 0) {
+      return result;
+    }
+    result = check_timespec(abs_timeout_or_null);
+    if (result != 0) {
+      return result;
     }
 
     int old_state = atomic_load_explicit(&rwlock->state, memory_order_relaxed);
@@ -382,16 +380,6 @@
       continue;
     }
 
-    timespec ts;
-    timespec* rel_timeout = NULL;
-
-    if (abs_timeout_or_null != NULL) {
-      rel_timeout = &ts;
-      if (!timespec_from_absolute_timespec(*rel_timeout, *abs_timeout_or_null, CLOCK_REALTIME)) {
-        return ETIMEDOUT;
-      }
-    }
-
     rwlock->pending_lock.lock();
     rwlock->pending_writer_count++;
 
@@ -401,10 +389,10 @@
     int old_serial = rwlock->pending_writer_wakeup_serial;
     rwlock->pending_lock.unlock();
 
-    int futex_ret = 0;
+    int futex_result = 0;
     if (!__can_acquire_write_lock(old_state)) {
-      futex_ret = __futex_wait_ex(&rwlock->pending_writer_wakeup_serial, rwlock->pshared,
-                                  old_serial, rel_timeout);
+      futex_result = __futex_wait_ex(&rwlock->pending_writer_wakeup_serial, rwlock->pshared,
+                                  old_serial, true, abs_timeout_or_null);
     }
 
     rwlock->pending_lock.lock();
@@ -415,7 +403,7 @@
     }
     rwlock->pending_lock.unlock();
 
-    if (futex_ret == -ETIMEDOUT) {
+    if (futex_result == -ETIMEDOUT) {
       return ETIMEDOUT;
     }
   }
@@ -427,7 +415,7 @@
   if (__predict_true(__pthread_rwlock_tryrdlock(rwlock) == 0)) {
     return 0;
   }
-  return __pthread_rwlock_timedrdlock(rwlock, NULL);
+  return __pthread_rwlock_timedrdlock(rwlock, nullptr);
 }
 
 int pthread_rwlock_timedrdlock(pthread_rwlock_t* rwlock_interface, const timespec* abs_timeout) {
@@ -446,7 +434,7 @@
   if (__predict_true(__pthread_rwlock_trywrlock(rwlock) == 0)) {
     return 0;
   }
-  return __pthread_rwlock_timedwrlock(rwlock, NULL);
+  return __pthread_rwlock_timedwrlock(rwlock, nullptr);
 }
 
 int pthread_rwlock_timedwrlock(pthread_rwlock_t* rwlock_interface, const timespec* abs_timeout) {
diff --git a/libc/bionic/semaphore.cpp b/libc/bionic/semaphore.cpp
index ff84443..79b5d63 100644
--- a/libc/bionic/semaphore.cpp
+++ b/libc/bionic/semaphore.cpp
@@ -220,7 +220,7 @@
       return 0;
     }
 
-    __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, NULL);
+    __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, false, nullptr);
   }
 }
 
@@ -235,36 +235,29 @@
   }
 
   // Check it as per POSIX.
-  if (abs_timeout == NULL || abs_timeout->tv_sec < 0 || abs_timeout->tv_nsec < 0 || abs_timeout->tv_nsec >= NS_PER_S) {
-    errno = EINVAL;
+  int result = check_timespec(abs_timeout);
+  if (result != 0) {
+    errno = result;
     return -1;
   }
 
   unsigned int shared = SEM_GET_SHARED(sem_count_ptr);
 
   while (true) {
-    // POSIX mandates CLOCK_REALTIME here.
-    timespec ts;
-    if (!timespec_from_absolute_timespec(ts, *abs_timeout, CLOCK_REALTIME)) {
-      errno = ETIMEDOUT;
-      return -1;
-    }
-
     // Try to grab the semaphore. If the value was 0, this will also change it to -1.
     if (__sem_dec(sem_count_ptr) > 0) {
-      break;
+      return 0;
     }
 
     // Contention detected. Wait for a wakeup event.
-    int ret = __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, &ts);
+    int result = __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, true, abs_timeout);
 
     // Return in case of timeout or interrupt.
-    if (ret == -ETIMEDOUT || ret == -EINTR) {
-      errno = -ret;
+    if (result == -ETIMEDOUT || result == -EINTR) {
+      errno = -result;
       return -1;
     }
   }
-  return 0;
 }
 
 int sem_post(sem_t* sem) {
diff --git a/libc/private/bionic_futex.h b/libc/private/bionic_futex.h
index 401577a..946d9dd 100644
--- a/libc/private/bionic_futex.h
+++ b/libc/private/bionic_futex.h
@@ -40,10 +40,12 @@
 
 struct timespec;
 
-static inline __always_inline int __futex(volatile void* ftx, int op, int value, const struct timespec* timeout) {
+static inline __always_inline int __futex(volatile void* ftx, int op, int value,
+                                          const struct timespec* timeout,
+                                          int bitset) {
   // Our generated syscall assembler sets errno, but our callers (pthread functions) don't want to.
   int saved_errno = errno;
-  int result = syscall(__NR_futex, ftx, op, value, timeout);
+  int result = syscall(__NR_futex, ftx, op, value, timeout, NULL, bitset);
   if (__predict_false(result == -1)) {
     result = -errno;
     errno = saved_errno;
@@ -52,19 +54,22 @@
 }
 
 static inline int __futex_wake(volatile void* ftx, int count) {
-  return __futex(ftx, FUTEX_WAKE, count, NULL);
+  return __futex(ftx, FUTEX_WAKE, count, NULL, 0);
 }
 
 static inline int __futex_wake_ex(volatile void* ftx, bool shared, int count) {
-  return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL);
+  return __futex(ftx, shared ? FUTEX_WAKE : FUTEX_WAKE_PRIVATE, count, NULL, 0);
 }
 
 static inline int __futex_wait(volatile void* ftx, int value, const struct timespec* timeout) {
-  return __futex(ftx, FUTEX_WAIT, value, timeout);
+  return __futex(ftx, FUTEX_WAIT, value, timeout, 0);
 }
 
-static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value, const struct timespec* timeout) {
-  return __futex(ftx, shared ? FUTEX_WAIT : FUTEX_WAIT_PRIVATE, value, timeout);
+static inline int __futex_wait_ex(volatile void* ftx, bool shared, int value,
+                                  bool use_realtime_clock, const struct timespec* abs_timeout) {
+  return __futex(ftx, (shared ? FUTEX_WAIT_BITSET : FUTEX_WAIT_BITSET_PRIVATE) |
+                 (use_realtime_clock ? FUTEX_CLOCK_REALTIME : 0), value, abs_timeout,
+                 FUTEX_BITSET_MATCH_ANY);
 }
 
 __END_DECLS
diff --git a/libc/private/bionic_lock.h b/libc/private/bionic_lock.h
index a36d1ed..eb73274 100644
--- a/libc/private/bionic_lock.h
+++ b/libc/private/bionic_lock.h
@@ -57,7 +57,7 @@
     }
     while (atomic_exchange_explicit(&state, LockedWithWaiter, memory_order_acquire) != Unlocked) {
       // TODO: As the critical section is brief, it is a better choice to spin a few times befor sleeping.
-      __futex_wait_ex(&state, process_shared, LockedWithWaiter, NULL);
+      __futex_wait_ex(&state, process_shared, LockedWithWaiter, false, nullptr);
     }
     return;
   }
diff --git a/libc/private/bionic_time_conversions.h b/libc/private/bionic_time_conversions.h
index cf0046a..294c29a 100644
--- a/libc/private/bionic_time_conversions.h
+++ b/libc/private/bionic_time_conversions.h
@@ -29,9 +29,12 @@
 #ifndef _BIONIC_TIME_CONVERSIONS_H
 #define _BIONIC_TIME_CONVERSIONS_H
 
+#include <errno.h>
 #include <time.h>
 #include <sys/cdefs.h>
 
+#include "private/bionic_constants.h"
+
 __BEGIN_DECLS
 
 __LIBC_HIDDEN__ bool timespec_from_timeval(timespec& ts, const timeval& tv);
@@ -39,8 +42,21 @@
 
 __LIBC_HIDDEN__ void timeval_from_timespec(timeval& tv, const timespec& ts);
 
-__LIBC_HIDDEN__ bool timespec_from_absolute_timespec(timespec& ts, const timespec& abs_ts, clockid_t clock);
+__LIBC_HIDDEN__ void absolute_timespec_from_timespec(timespec& abs_ts, const timespec& ts,
+                                                     clockid_t clock);
 
 __END_DECLS
 
+static inline int check_timespec(const timespec* ts) {
+  if (ts != nullptr) {
+    if (ts->tv_nsec < 0 || ts->tv_nsec >= NS_PER_S) {
+      return EINVAL;
+    }
+    if (ts->tv_sec < 0) {
+      return ETIMEDOUT;
+    }
+  }
+  return 0;
+}
+
 #endif