diff --git a/libcxx/test/std/utilities/charconv/charconv.msvc/test.pass.cpp b/libcxx/test/std/utilities/charconv/charconv.msvc/test.pass.cpp
--- a/libcxx/test/std/utilities/charconv/charconv.msvc/test.pass.cpp
+++ b/libcxx/test/std/utilities/charconv/charconv.msvc/test.pass.cpp
@@ -31,6 +31,10 @@
 #  define sprintf_s snprintf
 #endif
 
+#ifdef _MSVC_STL_VERSION
+#include <xutility>
+using std::_Bit_cast;
+#else
 // FUNCTION TEMPLATE _Bit_cast
 template <class _To, class _From,
           std::enable_if_t<sizeof(_To) == sizeof(_From) && std::is_trivially_copyable_v<_To> &&
@@ -39,6 +43,7 @@
 [[nodiscard]] constexpr _To _Bit_cast(const _From& _From_obj) noexcept {
   return __builtin_bit_cast(_To, _From_obj);
 }
+#endif
 
 // Includes Microsoft's test that tests the entire header.