diff --git a/libcxx/include/bit b/libcxx/include/bit
--- a/libcxx/include/bit
+++ b/libcxx/include/bit
@@ -72,10 +72,10 @@
 #include <version>
 
 #if defined(__IBMCPP__)
-#include "__support/ibm/support.h"
+#  include "__support/ibm/support.h"
 #endif
 #if defined(_LIBCPP_COMPILER_MSVC)
-#include <intrin.h>
+#  include <intrin.h>
 #endif
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -87,199 +87,123 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp __rotl(_Tp __t, unsigned int __cnt) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotl requires an unsigned integer type");
-    const unsigned int __dig = numeric_limits<_Tp>::digits;
-    if ((__cnt % __dig) == 0)
-        return __t;
-    return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-_Tp __rotr(_Tp __t, unsigned int __cnt) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__rotr requires an unsigned integer type");
-    const unsigned int __dig = numeric_limits<_Tp>::digits;
-    if ((__cnt % __dig) == 0)
-        return __t;
-    return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-int __countr_zero(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countr_zero requires an unsigned integer type");
-    if (__t == 0)
-        return numeric_limits<_Tp>::digits;
-
-    if      (sizeof(_Tp) <= sizeof(unsigned int))
-        return __libcpp_ctz(static_cast<unsigned int>(__t));
-    else if (sizeof(_Tp) <= sizeof(unsigned long))
-        return __libcpp_ctz(static_cast<unsigned long>(__t));
-    else if (sizeof(_Tp) <= sizeof(unsigned long long))
-        return __libcpp_ctz(static_cast<unsigned long long>(__t));
-    else
-    {
-        int __ret = 0;
-        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
-        while (static_cast<unsigned long long>(__t) == 0uLL)
-        {
-            __ret += __ulldigits;
-            __t >>= __ulldigits;
-        }
-        return __ret + __libcpp_ctz(static_cast<unsigned long long>(__t));
-    }
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-int __countl_zero(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countl_zero requires an unsigned integer type");
-    if (__t == 0)
-        return numeric_limits<_Tp>::digits;
-
-    if      (sizeof(_Tp) <= sizeof(unsigned int))
-        return __libcpp_clz(static_cast<unsigned int>(__t))
-              - (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
-    else if (sizeof(_Tp) <= sizeof(unsigned long))
-        return __libcpp_clz(static_cast<unsigned long>(__t))
-              - (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
-    else if (sizeof(_Tp) <= sizeof(unsigned long long))
-        return __libcpp_clz(static_cast<unsigned long long>(__t))
-              - (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
-    else
-    {
-        int __ret = 0;
-        int __iter = 0;
-        const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
-        while (true) {
-            __t = __rotr(__t, __ulldigits);
-            if ((__iter = __countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
-                break;
-            __ret += __iter;
-            }
-        return __ret + __iter;
-    }
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-int __countl_one(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countl_one requires an unsigned integer type");
-    return __t != numeric_limits<_Tp>::max()
-        ? __countl_zero(static_cast<_Tp>(~__t))
-        : numeric_limits<_Tp>::digits;
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-int __countr_one(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__countr_one requires an unsigned integer type");
-    return __t != numeric_limits<_Tp>::max()
-        ? __countr_zero(static_cast<_Tp>(~__t))
-        : numeric_limits<_Tp>::digits;
-}
-
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-int __popcount(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__popcount requires an unsigned integer type");
-    if      (sizeof(_Tp) <= sizeof(unsigned int))
-        return __libcpp_popcount(static_cast<unsigned int>(__t));
-    else if (sizeof(_Tp) <= sizeof(unsigned long))
-        return __libcpp_popcount(static_cast<unsigned long>(__t));
-    else if (sizeof(_Tp) <= sizeof(unsigned long long))
-        return __libcpp_popcount(static_cast<unsigned long long>(__t));
-    else
-    {
-        int __ret = 0;
-        while (__t != 0)
-        {
-            __ret += __libcpp_popcount(static_cast<unsigned long long>(__t));
-            __t >>= numeric_limits<unsigned long long>::digits;
-        }
-        return __ret;
-    }
-}
-
-// integral log base 2
-template<class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX11
-unsigned __bit_log2(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__bit_log2 requires an unsigned integer type");
-    return numeric_limits<_Tp>::digits - 1 - __countl_zero(__t);
-}
-
-template <class _Tp>
-_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR
-bool __has_single_bit(_Tp __t) _NOEXCEPT
-{
-    static_assert(__libcpp_is_unsigned_integer<_Tp>::value, "__has_single_bit requires an unsigned integer type");
-    return __t != 0 && (((__t & (__t - 1)) == 0));
-}
-
 #if _LIBCPP_STD_VER > 17
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotl(_Tp __t, unsigned int __cnt) noexcept {
-  return __rotl(__t, __cnt);
+  const unsigned int __dig = numeric_limits<_Tp>::digits;
+  if ((__cnt % __dig) == 0)
+    return __t;
+  return (__t << (__cnt % __dig)) | (__t >> (__dig - (__cnt % __dig)));
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr _Tp rotr(_Tp __t, unsigned int __cnt) noexcept {
-  return __rotr(__t, __cnt);
+  const unsigned int __dig = numeric_limits<_Tp>::digits;
+  if ((__cnt % __dig) == 0)
+    return __t;
+  return (__t >> (__cnt % __dig)) | (__t << (__dig - (__cnt % __dig)));
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int countl_zero(_Tp __t) noexcept {
-  return __countl_zero(__t);
+  if (__t == 0)
+    return numeric_limits<_Tp>::digits;
+
+  if (sizeof(_Tp) <= sizeof(unsigned int))
+    return __libcpp_clz(static_cast<unsigned int>(__t)) -
+           (numeric_limits<unsigned int>::digits - numeric_limits<_Tp>::digits);
+  else if (sizeof(_Tp) <= sizeof(unsigned long))
+    return __libcpp_clz(static_cast<unsigned long>(__t)) -
+           (numeric_limits<unsigned long>::digits - numeric_limits<_Tp>::digits);
+  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+    return __libcpp_clz(static_cast<unsigned long long>(__t)) -
+           (numeric_limits<unsigned long long>::digits - numeric_limits<_Tp>::digits);
+  else {
+    int __ret = 0;
+    int __iter = 0;
+    const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
+    while (true) {
+      __t = std::rotr(__t, __ulldigits);
+      if ((__iter = std::countl_zero(static_cast<unsigned long long>(__t))) != __ulldigits)
+        break;
+      __ret += __iter;
+    }
+    return __ret + __iter;
+  }
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int countl_one(_Tp __t) noexcept {
-  return __countl_one(__t);
+  return __t != numeric_limits<_Tp>::max() ? std::countl_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int countr_zero(_Tp __t) noexcept {
-  return __countr_zero(__t);
+  if (__t == 0)
+    return numeric_limits<_Tp>::digits;
+
+  if (sizeof(_Tp) <= sizeof(unsigned int))
+    return __libcpp_ctz(static_cast<unsigned int>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long))
+    return __libcpp_ctz(static_cast<unsigned long>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+    return __libcpp_ctz(static_cast<unsigned long long>(__t));
+  else {
+    int __ret = 0;
+    const unsigned int __ulldigits = numeric_limits<unsigned long long>::digits;
+    while (static_cast<unsigned long long>(__t) == 0uLL) {
+      __ret += __ulldigits;
+      __t >>= __ulldigits;
+    }
+    return __ret + std::__libcpp_ctz(static_cast<unsigned long long>(__t));
+  }
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int countr_one(_Tp __t) noexcept {
-  return __countr_one(__t);
+  return __t != numeric_limits<_Tp>::max() ? std::countr_zero(static_cast<_Tp>(~__t)) : numeric_limits<_Tp>::digits;
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
-  return __popcount(__t);
+  if (sizeof(_Tp) <= sizeof(unsigned int))
+    return __libcpp_popcount(static_cast<unsigned int>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long))
+    return __libcpp_popcount(static_cast<unsigned long>(__t));
+  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+    return __libcpp_popcount(static_cast<unsigned long long>(__t));
+  else {
+    int __ret = 0;
+    while (__t != 0) {
+      __ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
+      __t >>= numeric_limits<unsigned long long>::digits;
+    }
+    return __ret;
+  }
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr bool has_single_bit(_Tp __t) noexcept {
-  return __has_single_bit(__t);
+  return __t != 0 && (((__t & (__t - 1)) == 0));
+}
+
+// integral log base 2
+template <__libcpp_unsigned_integer _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp __bit_log2(_Tp __t) noexcept {
+  return numeric_limits<_Tp>::digits - 1 - std::countl_zero(__t);
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_floor(_Tp __t) noexcept {
-  return __t == 0 ? 0 : _Tp{1} << __bit_log2(__t);
+  return __t == 0 ? 0 : _Tp{1} << std::__bit_log2(__t);
 }
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr _Tp bit_ceil(_Tp __t) noexcept {
   if (__t < 2)
     return 1;
-  const unsigned __n = numeric_limits<_Tp>::digits - countl_zero((_Tp)(__t - 1u));
+  const unsigned __n = numeric_limits<_Tp>::digits - std::countl_zero((_Tp)(__t - 1u));
   _LIBCPP_ASSERT(__n != numeric_limits<_Tp>::digits, "Bad input to bit_ceil");
 
   if constexpr (sizeof(_Tp) >= sizeof(unsigned))
@@ -293,20 +217,19 @@
 
 template <__libcpp_unsigned_integer _Tp>
 _LIBCPP_HIDE_FROM_ABI constexpr int bit_width(_Tp __t) noexcept {
-  return __t == 0 ? 0 : __bit_log2(__t) + 1;
-}
-
-enum class endian
-{
-    little = 0xDEAD,
-    big    = 0xFACE,
-#if defined(_LIBCPP_LITTLE_ENDIAN)
-    native = little
-#elif defined(_LIBCPP_BIG_ENDIAN)
-    native = big
-#else
-    native = 0xCAFE
-#endif
+  return __t == 0 ? 0 : std::__bit_log2(__t) + 1;
+}
+
+enum class endian {
+  little = 0xDEAD,
+  big = 0xFACE,
+#  if defined(_LIBCPP_LITTLE_ENDIAN)
+  native = little
+#  elif defined(_LIBCPP_BIG_ENDIAN)
+  native = big
+#  else
+  native = 0xCAFE
+#  endif
 };
 
 #endif // _LIBCPP_STD_VER > 17