diff --git a/libcxx/include/__config b/libcxx/include/__config
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -953,10 +953,6 @@
 #define _LIBCPP_WCTYPE_IS_MASK
 #endif
 
-#if _LIBCPP_STD_VER <= 17 || !defined(__cpp_char8_t)
-#define _LIBCPP_NO_HAS_CHAR8_T
-#endif
-
 // Deprecation macros.
 //
 // Deprecations warnings are always enabled, except when users explicitly opt-out
diff --git a/libcxx/include/__string b/libcxx/include/__string
--- a/libcxx/include/__string
+++ b/libcxx/include/__string
@@ -57,6 +57,7 @@
 #include <algorithm>  // for search and min
 #include <cstdio>     // For EOF.
 #include <memory>     // for __murmur2_or_cityhash
+#include <version>    // for feature-test macros
 
 #include <__debug>
 
@@ -579,7 +580,7 @@
 }
 
 
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 
 template <>
 struct _LIBCPP_TEMPLATE_VIS char_traits<char8_t>
@@ -686,7 +687,7 @@
     return nullptr;
 }
 
-#endif // #_LIBCPP_NO_HAS_CHAR8_T
+#endif // __cpp_lib_char8_t
 
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 
diff --git a/libcxx/include/atomic b/libcxx/include/atomic
--- a/libcxx/include/atomic
+++ b/libcxx/include/atomic
@@ -1127,7 +1127,7 @@
 #if defined(__CLANG_ATOMIC_BOOL_LOCK_FREE)
 # define ATOMIC_BOOL_LOCK_FREE      __CLANG_ATOMIC_BOOL_LOCK_FREE
 # define ATOMIC_CHAR_LOCK_FREE      __CLANG_ATOMIC_CHAR_LOCK_FREE
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 # define ATOMIC_CHAR8_T_LOCK_FREE   __CLANG_ATOMIC_CHAR8_T_LOCK_FREE
 #endif
 # define ATOMIC_CHAR16_T_LOCK_FREE  __CLANG_ATOMIC_CHAR16_T_LOCK_FREE
@@ -1141,7 +1141,7 @@
 #elif defined(__GCC_ATOMIC_BOOL_LOCK_FREE)
 # define ATOMIC_BOOL_LOCK_FREE      __GCC_ATOMIC_BOOL_LOCK_FREE
 # define ATOMIC_CHAR_LOCK_FREE      __GCC_ATOMIC_CHAR_LOCK_FREE
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 # define ATOMIC_CHAR8_T_LOCK_FREE   __GCC_ATOMIC_CHAR8_T_LOCK_FREE
 #endif
 # define ATOMIC_CHAR16_T_LOCK_FREE  __GCC_ATOMIC_CHAR16_T_LOCK_FREE
@@ -1458,7 +1458,7 @@
 template<> struct __cxx_is_always_lock_free<char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<signed char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
 template<> struct __cxx_is_always_lock_free<unsigned char> { enum { __value = 2 == ATOMIC_CHAR_LOCK_FREE }; };
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 template<> struct __cxx_is_always_lock_free<char8_t> { enum { __value = 2 == ATOMIC_CHAR8_T_LOCK_FREE }; };
 #endif
 template<> struct __cxx_is_always_lock_free<char16_t> { enum { __value = 2 == ATOMIC_CHAR16_T_LOCK_FREE }; };
@@ -2732,7 +2732,7 @@
 typedef atomic<unsigned long>      atomic_ulong;
 typedef atomic<long long>          atomic_llong;
 typedef atomic<unsigned long long> atomic_ullong;
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 typedef atomic<char8_t>            atomic_char8_t;
 #endif
 typedef atomic<char16_t>           atomic_char16_t;
diff --git a/libcxx/include/cstddef b/libcxx/include/cstddef
--- a/libcxx/include/cstddef
+++ b/libcxx/include/cstddef
@@ -59,7 +59,7 @@
 template <>          struct __libcpp_is_integral<signed char>        { enum { value = 1 }; };
 template <>          struct __libcpp_is_integral<unsigned char>      { enum { value = 1 }; };
 template <>          struct __libcpp_is_integral<wchar_t>            { enum { value = 1 }; };
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 template <>          struct __libcpp_is_integral<char8_t>            { enum { value = 1 }; };
 #endif
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
diff --git a/libcxx/include/iosfwd b/libcxx/include/iosfwd
--- a/libcxx/include/iosfwd
+++ b/libcxx/include/iosfwd
@@ -93,6 +93,7 @@
 
 #include <__config>
 #include <wchar.h>  // for mbstate_t
+#include <version>  // for feature-test macros
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -104,7 +105,7 @@
 
 template<class _CharT>  struct _LIBCPP_TEMPLATE_VIS char_traits;
 template<> struct char_traits<char>;
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 template<> struct char_traits<char8_t>;
 #endif
 template<> struct char_traits<char16_t>;
@@ -188,7 +189,7 @@
 template <class _State>             class _LIBCPP_TEMPLATE_VIS fpos;
 typedef fpos<mbstate_t>    streampos;
 typedef fpos<mbstate_t>    wstreampos;
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 typedef fpos<mbstate_t>    u8streampos;
 #endif
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
diff --git a/libcxx/include/string b/libcxx/include/string
--- a/libcxx/include/string
+++ b/libcxx/include/string
@@ -4327,7 +4327,7 @@
     __lhs.swap(__rhs);
 }
 
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 typedef basic_string<char8_t> u8string;
 #endif
 
@@ -4506,7 +4506,7 @@
         return basic_string<wchar_t> (__str, __len);
     }
 
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
     inline _LIBCPP_INLINE_VISIBILITY
     basic_string<char8_t> operator "" s(const char8_t *__str, size_t __len) _NOEXCEPT
     {
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -777,7 +777,7 @@
            basic_string_view<_CharT, _Traits> __str);
 
 typedef basic_string_view<char>     string_view;
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
 typedef basic_string_view<char8_t>  u8string_view;
 #endif
 typedef basic_string_view<char16_t> u16string_view;
@@ -813,7 +813,7 @@
         return basic_string_view<wchar_t> (__str, __len);
     }
 
-#ifndef _LIBCPP_NO_HAS_CHAR8_T
+#if defined(__cpp_lib_char8_t)
     inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
     basic_string_view<char8_t> operator "" sv(const char8_t *__str, size_t __len) _NOEXCEPT
     {
diff --git a/libcxx/include/version b/libcxx/include/version
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -249,7 +249,7 @@
 # endif
 // # define __cpp_lib_bind_front                           201811L
 // # define __cpp_lib_bit_cast                             201806L
-# if !defined(_LIBCPP_NO_HAS_CHAR8_T)
+# if defined(__cpp_char8_t)
 #   define __cpp_lib_char8_t                            201811L
 # endif
 // # define __cpp_lib_concepts                             201806L
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -336,7 +336,7 @@
     "headers": ["atomic", "filesystem", "istream", "limits", "locale", "ostream",
                 "string", "string_view"],
     "depends": "defined(__cpp_char8_t)",
-    "internal_depends": "!defined(_LIBCPP_NO_HAS_CHAR8_T)",
+    "internal_depends": "defined(__cpp_char8_t)",
    }, {
     "name": "__cpp_lib_erase_if",
     "values": { "c++2a": int(202002) },