diff --git a/libcxx/include/__std_clang_module b/libcxx/include/__std_clang_module
--- a/libcxx/include/__std_clang_module
+++ b/libcxx/include/__std_clang_module
@@ -30,6 +30,12 @@
 #include <algorithm>
 #include <any>
 #include <array>
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+#include <atomic>
+#endif
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <barrier>
+#endif
 #include <bit>
 #include <bitset>
 #include <cassert>
@@ -43,7 +49,13 @@
 #include <cinttypes>
 #include <ciso646>
 #include <climits>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <clocale>
+#endif
 #include <cmath>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <codecvt>
+#endif
 #include <compare>
 #include <complex.h>
 #include <complex>
@@ -63,6 +75,12 @@
 #include <ctime>
 #include <ctype.h>
 #include <cuchar>
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#include <cwchar>
+#endif
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#include <cwctype>
+#endif
 #include <deque>
 #include <errno.h>
 #include <exception>
@@ -75,6 +93,9 @@
 #include <experimental/map>
 #include <experimental/memory_resource>
 #include <experimental/propagate_const>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <experimental/regex>
+#endif
 #include <experimental/set>
 #include <experimental/simd>
 #include <experimental/string>
@@ -88,14 +109,41 @@
 #include <float.h>
 #include <format>
 #include <forward_list>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <fstream>
+#endif
 #include <functional>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <future>
+#endif
 #include <initializer_list>
 #include <inttypes.h>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <iomanip>
+#endif
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <ios>
+#endif
 #include <iosfwd>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <iostream>
+#endif
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <istream>
+#endif
 #include <iterator>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <latch>
+#endif
 #include <limits.h>
 #include <limits>
 #include <list>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <locale.h>
+#endif
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <locale>
+#endif
 #include <map>
 #include <math.h>
 #include <mdspan>
@@ -106,28 +154,58 @@
 #include <numbers>
 #include <numeric>
 #include <optional>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <ostream>
+#endif
 #include <print>
 #include <queue>
 #include <random>
 #include <ranges>
 #include <ratio>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <regex>
+#endif
 #include <scoped_allocator>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <semaphore>
+#endif
 #include <set>
 #include <setjmp.h>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <shared_mutex>
+#endif
 #include <source_location>
 #include <span>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <sstream>
+#endif
 #include <stack>
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
+#include <stdatomic.h>
+#endif
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdexcept>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <stop_token>
+#endif
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <streambuf>
+#endif
 #include <string.h>
 #include <string>
 #include <string_view>
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#include <strstream>
+#endif
 #include <system_error>
 #include <tgmath.h>
+#if !defined(_LIBCPP_HAS_NO_THREADS)
+#include <thread>
+#endif
 #include <tuple>
 #include <type_traits>
 #include <typeindex>
@@ -140,43 +218,9 @@
 #include <variant>
 #include <vector>
 #include <version>
-
-#ifndef _LIBCPP_HAS_NO_ATOMIC_HEADER
-#  include <atomic>
-#  include <stdatomic.h>
-#endif
-
-#ifndef _LIBCPP_HAS_NO_LOCALIZATION
-#  include <clocale>
-#  include <codecvt>
-#  include <experimental/regex>
-#  include <fstream>
-#  include <iomanip>
-#  include <ios>
-#  include <iostream>
-#  include <istream>
-#  include <locale.h>
-#  include <locale>
-#  include <ostream>
-#  include <regex>
-#  include <sstream>
-#  include <streambuf>
-#  include <strstream>
-#endif
-
-#ifndef _LIBCPP_HAS_NO_THREADS
-#  include <barrier>
-#  include <future>
-#  include <latch>
-#  include <semaphore>
-#  include <shared_mutex>
-#  include <stop_token>
-#  include <thread>
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#include <wchar.h>
 #endif
-
-#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-#  include <cwchar>
-#  include <cwctype>
-#  include <wchar.h>
-#  include <wctype.h>
+#if !defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)
+#include <wctype.h>
 #endif
diff --git a/libcxx/utils/generate_std_clang_module_header.py b/libcxx/utils/generate_std_clang_module_header.py
--- a/libcxx/utils/generate_std_clang_module_header.py
+++ b/libcxx/utils/generate_std_clang_module_header.py
@@ -11,11 +11,7 @@
 
 import libcxx.header_information
 
-public_headers = libcxx.header_information.public_headers
-header_include_requirements = libcxx.header_information.header_include_requirements
-always_available_headers = frozenset(public_headers).difference(
-    *header_include_requirements.values()
-)
+header_restrictions = libcxx.header_information.header_restrictions
 
 libcxx_include_directory = os.path.join(
     os.path.dirname(os.path.dirname(os.path.realpath(__file__))), "include"
@@ -58,25 +54,10 @@
     )
     # Include the angle brackets in sorting so that <a.h> sorts before <a>
     # like check-format wants.
-    for include in sorted([f"<{header}>" for header in always_available_headers]):
+    for include, header in sorted([(f"<{header}>", header) for header in libcxx.header_information.public_headers]):
+        header_restriction = header_restrictions.get(header)
+        if header_restriction:
+            std_clang_module_header.write(f"#if {header_restriction}\n")
         std_clang_module_header.write(f"#include {include}\n")
-
-    for requirements, headers in sorted(
-        header_include_requirements.items(), key=operator.itemgetter(0)
-    ):
-        std_clang_module_header.write("\n")
-        if len(requirements) == 1:
-            std_clang_module_header.write("#ifndef ")
-            std_clang_module_header.write(requirements[0])
-        else:
-            std_clang_module_header.write("#if")
-            for index, requirement in enumerate(requirements):
-                if index > 0:
-                    std_clang_module_header.write(" &&")
-                std_clang_module_header.write(f" !defined({requirement})")
-        std_clang_module_header.write("\n")
-
-        for include in sorted([f"<{header}>" for header in headers]):
-            std_clang_module_header.write(f"#  include {include}\n")
-
-        std_clang_module_header.write("#endif\n")
+        if header_restriction:
+            std_clang_module_header.write(f"#endif\n")
diff --git a/libcxx/utils/libcxx/header_information.py b/libcxx/utils/libcxx/header_information.py
--- a/libcxx/utils/libcxx/header_information.py
+++ b/libcxx/utils/libcxx/header_information.py
@@ -8,6 +8,46 @@
 
 import os, pathlib
 
+header_restrictions = {
+    # headers with #error directives
+    "atomic": "!defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)",
+    "stdatomic.h": "!defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)",
+
+    # headers with #error directives
+    "ios": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "locale.h": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    # transitive includers of the above headers
+    "clocale": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "codecvt": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "experimental/regex": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "fstream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "iomanip": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "iostream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "istream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "locale": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "ostream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "regex": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "sstream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "streambuf": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+    "strstream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
+
+    # headers with #error directives
+    "barrier": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "future": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "latch": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "semaphore": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "shared_mutex": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "stop_token": "!defined(_LIBCPP_HAS_NO_THREADS)",
+    "thread": "!defined(_LIBCPP_HAS_NO_THREADS)",
+
+    # headers with #error directives
+    "wchar.h": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
+    "wctype.h": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
+    # transitive includers of the above headers
+    "cwchar": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
+    "cwctype": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
+}
+
 lit_header_restrictions = {
     "barrier": "// UNSUPPORTED: no-threads, c++03, c++11, c++14, c++17",
     "clocale": "// UNSUPPORTED: no-localization",
@@ -57,52 +97,6 @@
     "wctype.h": "// UNSUPPORTED: no-wide-characters",
 }
 
-header_include_requirements = {
-    ("_LIBCPP_HAS_NO_ATOMIC_HEADER",): (
-        # headers with #error directives
-        "atomic",
-        # transitive includers of the above headers
-        "stdatomic.h",
-    ),
-    ("_LIBCPP_HAS_NO_LOCALIZATION",): (
-        # headers with #error directives
-        "ios",
-        "locale.h",
-        # transitive includers of the above headers
-        "clocale",
-        "codecvt",
-        "experimental/regex",
-        "fstream",
-        "iomanip",
-        "iostream",
-        "istream",
-        "locale",
-        "ostream",
-        "regex",
-        "sstream",
-        "streambuf",
-        "strstream",
-    ),
-    ("_LIBCPP_HAS_NO_THREADS",): (
-        # headers with #error directives
-        "barrier",
-        "future",
-        "latch",
-        "semaphore",
-        "shared_mutex",
-        "stop_token",
-        "thread",
-    ),
-    ("_LIBCPP_HAS_NO_WIDE_CHARACTERS",): (
-        # headers with #error directives
-        "wchar.h",
-        "wctype.h",
-        # transitive includers of the above headers
-        "cwchar",
-        "cwctype",
-    ),
-}
-
 # This table was produced manually, by grepping the TeX source of the Standard's
 # library clauses for the string "#include". Each header's synopsis contains
 # explicit "#include" directives for its mandatory inclusions.