diff --git a/include/details/__config b/include/details/__config
index 9bbce7b..1ed4d44 100644
--- a/include/details/__config
+++ b/include/details/__config
@@ -49,10 +49,10 @@ THE SOFTWARE.
 #define _LIBCPP_HAS_NO_INT128
 #define _LIBCPP_FREESTANDING
 #define _LIBCPP_HAS_NO_SEMAPHORES
+#define _LIBCPP_HAS_NO_IS_AGGREGATE
 #define _LIBCPP_HAS_NO_THREAD_CONTENTION_TABLE
 #define _LIBCPP_HAS_NO_THREAD_CONTENTION_STATE
 #define _LIBCPP_HAS_NO_PLATFORM_WAIT
-#define _LIBCPP_HAS_CLOCK_API_EXTERNAL
 #ifndef _LIBCUPP_HAS_TREE_BARRIER
 # define _LIBCPP_HAS_NO_TREE_BARRIER
 #endif
diff --git a/include/simt/chrono b/include/simt/chrono
index fe2204a..db4f591 100644
--- a/include/simt/chrono
+++ b/include/simt/chrono
@@ -26,10 +26,6 @@ THE SOFTWARE.
 #ifndef _SIMT_CHRONO
 #define _SIMT_CHRONO
 
-#ifndef __CUDACC_RTC__
-    #include <chrono>
-#endif //__CUDACC_RTC__
-
 #include "ctime"
 #include "type_traits"
 #include "ratio"
@@ -38,63 +34,27 @@ THE SOFTWARE.
 
 #include "../details/__config"
 
+#ifdef _LIBCUDACXX_USE_CXX20_CHRONO
+#  define _LIBCPP_STD_VER_PREV _LIBCPP_STD_VER
+#  undef _LIBCPP_STD_VER
+#  define _LIBCPP_STD_VER 20
+#endif //_LIBCUDACXX_USE_CXX20_CHRONO
+
+#ifndef __CUDACC_RTC__
+    #include <chrono>
+#endif //__CUDACC_RTC__
+
+#define _LIBCUDACXX_USE_CUDA_CLOCK
+
 #include "../../libcxx/include/chrono"
 
-_LIBCPP_BEGIN_NAMESPACE_STD
-
-namespace chrono {
-
-class _LIBCPP_TYPE_VIS system_clock
-{
-public:
-    typedef nanoseconds                      duration;
-    typedef duration::rep                    rep;
-    typedef duration::period                 period;
-    typedef chrono::time_point<system_clock> time_point;
-    static _LIBCPP_CONSTEXPR_AFTER_CXX11 const bool is_steady = false;
-
-    inline _LIBCPP_INLINE_VISIBILITY
-    static time_point now() _NOEXCEPT 
-    {
-#ifdef __CUDA_ARCH__
-        uint64_t time;
-        asm("mov.u64  %0, %globaltimer;":"=l"(time)::);
-        return time_point(nanoseconds(time));
-#else
-        return time_point(nanoseconds(
-                ::std::chrono::duration_cast<::std::chrono::nanoseconds>(
-                    ::std::chrono::system_clock::now().time_since_epoch()
-                ).count()
-               ));
-#endif
-    }
-    inline _LIBCPP_INLINE_VISIBILITY
-    static time_t to_time_t(const time_point& __t) _NOEXCEPT 
-    {
-        return time_t(duration_cast<seconds>(__t.time_since_epoch()).count());
-    }
-    inline _LIBCPP_INLINE_VISIBILITY
-    static time_point from_time_t(time_t __t) _NOEXCEPT
-    {
-        return time_point(seconds(__t));;
-    }
-};
-
-using steady_clock = system_clock;
-using high_resolution_clock = steady_clock;
-
-#if _LIBCPP_STD_VER > 17
-
-template <class _Duration>
-using sys_time    = time_point<system_clock, _Duration>;
-using sys_seconds = sys_time<seconds>;
-using sys_days    = sys_time<days>;
-
-#endif
-
-}
-
-_LIBCPP_END_NAMESPACE_STD
+#undef _LIBCUDACXX_USE_CUDA_CLOCK
+
+#ifdef _LIBCUDACXX_USE_CXX20_CHRONO
+#  undef _LIBCPP_STD_VER
+#  define _LIBCPP_STD_VER _LIBCPP_STD_VER_PREV
+#  undef _LIBCPP_STD_VER_PREV
+#endif //_LIBCUDACXX_USE_CXX20_CHRONO
 
 #endif //_SIMT_CHRONO
 
diff --git a/include/simt/type_traits b/include/simt/type_traits
index 5e29b70..f6a81ab 100644
--- a/include/simt/type_traits
+++ b/include/simt/type_traits
@@ -25,6 +25,12 @@ THE SOFTWARE.
 #ifndef _SIMT_TYPE_TRAITS
 #define _SIMT_TYPE_TRAITS
 
+#ifdef _LIBCUDACXX_USE_CXX17_TYPE_TRAITS
+#  define _LIBCPP_STD_VER_PREV _LIBCPP_STD_VER
+#  undef _LIBCPP_STD_VER
+#  define _LIBCPP_STD_VER 17
+#endif //_LIBCUDACXX_USE_CXX17_TYPE_TRAITS
+
 #ifndef __CUDACC_RTC__
     #include <type_traits>
 #endif //__CUDACC_RTC__
@@ -35,4 +41,10 @@ THE SOFTWARE.
 
 #include "../../libcxx/include/type_traits"
 
+#ifdef _LIBCUDACXX_USE_CXX17_TYPE_TRAITS
+#  undef _LIBCPP_STD_VER
+#  define _LIBCPP_STD_VER _LIBCPP_STD_VER_PREV
+#  undef _LIBCPP_STD_VER_PREV
+#endif //_LIBCUDACXX_USE_CXX17_TYPE_TRAITS
+
 #endif //_SIMT_TYPE_TRAITS
diff --git a/libcxx b/libcxx
index a4ace1c..1f4f3a4 160000
--- a/libcxx
+++ b/libcxx
@@ -1 +1 @@
-Subproject commit a4ace1ce72e2e5376c4e3965e632357e7d55e0b6
+Subproject commit 1f4f3a4e4fbc2fec63807e43db251600b7ad8dc4