diff --git a/include/__config b/include/__config
index 17e5e04..0a5e8e5 100644
--- a/include/__config
+++ b/include/__config
@@ -1087,12 +1087,6 @@
 #  endif // _LIBCPP_HAS_THREAD_API
 #endif // _LIBCPP_HAS_NO_THREADS
 
-#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
-#  if (defined(__ANDROID__) && __ANDROID_API__ >= 30) || _LIBCPP_GLIBC_PREREQ(2, 30)
-#    define _LIBCPP_HAS_COND_CLOCKWAIT
-#  endif
-#endif
-
 #if defined(_LIBCPP_HAS_NO_THREADS) && defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
 #error _LIBCPP_HAS_THREAD_API_PTHREAD may only be defined when \
        _LIBCPP_HAS_NO_THREADS is not defined.
diff --git a/include/__mutex_base b/include/__mutex_base
index a4ac361..a85ded8 100644
--- a/include/__mutex_base
+++ b/include/__mutex_base
@@ -15,7 +15,6 @@
 #include <system_error>
 #include <__threading_support>
 
-#include <time.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -338,75 +337,23 @@
 private:
     void __do_timed_wait(unique_lock<mutex>& __lk,
        chrono::time_point<chrono::system_clock, chrono::nanoseconds>) _NOEXCEPT;
-#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
-    void __do_timed_wait(unique_lock<mutex>& __lk,
-       chrono::time_point<chrono::steady_clock, chrono::nanoseconds>) _NOEXCEPT;
-#endif
-    template <class _Clock>
-    void __do_timed_wait(unique_lock<mutex>& __lk,
-       chrono::time_point<_Clock, chrono::nanoseconds>) _NOEXCEPT;
 };
 #endif // !_LIBCPP_HAS_NO_THREADS
 
-template <class _Rep, class _Period>
+template <class _To, class _Rep, class _Period>
 inline _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
-    is_floating_point<_Rep>::value,
-    chrono::nanoseconds
+    chrono::__is_duration<_To>::value,
+    _To
 >::type
-__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
+__ceil(chrono::duration<_Rep, _Period> __d)
 {
     using namespace chrono;
-    using __ratio = ratio_divide<_Period, nano>;
-    using __ns_rep = nanoseconds::rep;
-    _Rep __result_float = __d.count() * __ratio::num / __ratio::den;
-
-    _Rep __result_max = numeric_limits<__ns_rep>::max();
-    if (__result_float >= __result_max) {
-        return nanoseconds::max();
-    }
-
-    _Rep __result_min = numeric_limits<__ns_rep>::min();
-    if (__result_float <= __result_min) {
-        return nanoseconds::min();
-    }
-
-    return nanoseconds(static_cast<__ns_rep>(__result_float));
-}
-
-template <class _Rep, class _Period>
-inline _LIBCPP_INLINE_VISIBILITY
-typename enable_if
-<
-    !is_floating_point<_Rep>::value,
-    chrono::nanoseconds
->::type
-__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
-{
-    using namespace chrono;
-    if (__d.count() == 0) {
-        return nanoseconds(0);
-    }
-
-    using __ratio = ratio_divide<_Period, nano>;
-    using __ns_rep = nanoseconds::rep;
-    __ns_rep __result_max = std::numeric_limits<__ns_rep>::max();
-    if (__d.count() > 0 && __d.count() > __result_max / __ratio::num) {
-        return nanoseconds::max();
-    }
-
-    __ns_rep __result_min = std::numeric_limits<__ns_rep>::min();
-    if (__d.count() < 0 && __d.count() < __result_min / __ratio::num) {
-        return nanoseconds::min();
-    }
-
-    __ns_rep __result = __d.count() * __ratio::num / __ratio::den;
-    if (__result == 0) {
-        return nanoseconds(1);
-    }
-
-    return nanoseconds(__result);
+    _To __r = duration_cast<_To>(__d);
+    if (__r < __d)
+        ++__r;
+    return __r;
 }
 
 #ifndef _LIBCPP_HAS_NO_THREADS
@@ -424,15 +371,7 @@
                                const chrono::time_point<_Clock, _Duration>& __t)
 {
     using namespace chrono;
-    using __clock_tp_ns = time_point<_Clock, nanoseconds>;
-
-    typename _Clock::time_point __now = _Clock::now();
-    if (__t <= __now)
-        return cv_status::timeout;
-
-    __clock_tp_ns __t_ns = __clock_tp_ns(__safe_nanosecond_cast(__t.time_since_epoch()));
-
-    __do_timed_wait(__lk, __t_ns);
+    wait_for(__lk, __t - _Clock::now());
     return _Clock::now() < __t ? cv_status::no_timeout : cv_status::timeout;
 }
 
@@ -458,25 +397,15 @@
     using namespace chrono;
     if (__d <= __d.zero())
         return cv_status::timeout;
-    using __ns_rep = nanoseconds::rep;
+    typedef time_point<system_clock, duration<long double, nano> > __sys_tpf;
+    typedef time_point<system_clock, nanoseconds> __sys_tpi;
+    __sys_tpf _Max = __sys_tpi::max();
     steady_clock::time_point __c_now = steady_clock::now();
-
-#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
-    using __clock_tp_ns = time_point<steady_clock, nanoseconds>;
-    __ns_rep __now_count_ns = __safe_nanosecond_cast(__c_now.time_since_epoch()).count();
-#else
-    using __clock_tp_ns = time_point<system_clock, nanoseconds>;
-    __ns_rep __now_count_ns = __safe_nanosecond_cast(system_clock::now().time_since_epoch()).count();
-#endif
-
-    __ns_rep __d_ns_count = __safe_nanosecond_cast(__d).count();
-
-    if (__now_count_ns > numeric_limits<__ns_rep>::max() - __d_ns_count) {
-        __do_timed_wait(__lk, __clock_tp_ns::max());
-    } else {
-        __do_timed_wait(__lk, __clock_tp_ns(nanoseconds(__now_count_ns + __d_ns_count)));
-    }
-
+    system_clock::time_point __s_now = system_clock::now();
+    if (_Max - __d > __s_now)
+        __do_timed_wait(__lk, __s_now + __ceil<nanoseconds>(__d));
+    else
+        __do_timed_wait(__lk, __sys_tpi::max());
     return steady_clock::now() - __c_now < __d ? cv_status::no_timeout :
                                                  cv_status::timeout;
 }
@@ -492,46 +421,6 @@
                       _VSTD::move(__pred));
 }
 
-#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
-inline
-void
-condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
-     chrono::time_point<chrono::steady_clock, chrono::nanoseconds> __tp) _NOEXCEPT
-{
-    using namespace chrono;
-    if (!__lk.owns_lock())
-        __throw_system_error(EPERM,
-                            "condition_variable::timed wait: mutex not locked");
-    nanoseconds __d = __tp.time_since_epoch();
-    timespec __ts;
-    seconds __s = duration_cast<seconds>(__d);
-    using __ts_sec = decltype(__ts.tv_sec);
-    const __ts_sec __ts_sec_max = numeric_limits<__ts_sec>::max();
-    if (__s.count() < __ts_sec_max)
-    {
-        __ts.tv_sec = static_cast<__ts_sec>(__s.count());
-        __ts.tv_nsec = (__d - __s).count();
-    }
-    else
-    {
-        __ts.tv_sec = __ts_sec_max;
-        __ts.tv_nsec = giga::num - 1;
-    }
-    int __ec = pthread_cond_clockwait(&__cv_, __lk.mutex()->native_handle(), CLOCK_MONOTONIC, &__ts);
-    if (__ec != 0 && __ec != ETIMEDOUT)
-        __throw_system_error(__ec, "condition_variable timed_wait failed");
-}
-#endif // _LIBCPP_HAS_COND_CLOCKWAIT
-
-template <class _Clock>
-inline
-void
-condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
-     chrono::time_point<_Clock, chrono::nanoseconds> __tp) _NOEXCEPT
-{
-    wait_for(__lk, __tp - _Clock::now());
-}
-
 #endif // !_LIBCPP_HAS_NO_THREADS
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/test/std/thread/thread.condition/thread.condition.condvar/wait_until.pass.cpp b/test/std/thread/thread.condition/thread.condition.condvar/wait_until.pass.cpp
index e5c77f2..12ccf3f 100644
--- a/test/std/thread/thread.condition/thread.condition.condvar/wait_until.pass.cpp
+++ b/test/std/thread/thread.condition/thread.condition.condvar/wait_until.pass.cpp
@@ -25,12 +25,12 @@
 
 #include "test_macros.h"
 
-struct TestClock
+struct Clock
 {
     typedef std::chrono::milliseconds duration;
     typedef duration::rep             rep;
     typedef duration::period          period;
-    typedef std::chrono::time_point<TestClock> time_point;
+    typedef std::chrono::time_point<Clock> time_point;
     static const bool is_steady =  true;
 
     static time_point now()
@@ -50,40 +50,35 @@
 
 int runs = 0;
 
-template <typename Clock>
 void f()
 {
     std::unique_lock<std::mutex> lk(mut);
     assert(test2 == 0);
     test1 = 1;
     cv.notify_one();
-    typename Clock::time_point t0 = Clock::now();
-    typename Clock::time_point t = t0 + std::chrono::milliseconds(250);
+    Clock::time_point t0 = Clock::now();
+    Clock::time_point t = t0 + Clock::duration(250);
     while (test2 == 0 && cv.wait_until(lk, t) == std::cv_status::no_timeout)
         ;
-    typename Clock::time_point t1 = Clock::now();
+    Clock::time_point t1 = Clock::now();
     if (runs == 0)
     {
-        assert(t1 - t0 < std::chrono::milliseconds(250));
+        assert(t1 - t0 < Clock::duration(250));
         assert(test2 != 0);
     }
     else
     {
-        assert(t1 - t0 - std::chrono::milliseconds(250) < std::chrono::milliseconds(50));
+        assert(t1 - t0 - Clock::duration(250) < Clock::duration(50));
         assert(test2 == 0);
     }
     ++runs;
 }
 
-template <typename Clock>
-void run_test()
+int main(int, char**)
 {
-    runs = 0;
-    test1 = 0;
-    test2 = 0;
     {
         std::unique_lock<std::mutex>lk(mut);
-        std::thread t(f<Clock>);
+        std::thread t(f);
         assert(test1 == 0);
         while (test1 == 0)
             cv.wait(lk);
@@ -97,7 +92,7 @@
     test2 = 0;
     {
         std::unique_lock<std::mutex>lk(mut);
-        std::thread t(f<Clock>);
+        std::thread t(f);
         assert(test1 == 0);
         while (test1 == 0)
             cv.wait(lk);
@@ -105,12 +100,6 @@
         lk.unlock();
         t.join();
     }
-}
 
-int main(int, char**)
-{
-    run_test<TestClock>();
-    run_test<std::chrono::steady_clock>();
-    run_test<std::chrono::system_clock>();
-    return 0;
+  return 0;
 }