diff --git a/include/__memory_resource/synchronized_pool_resource.h b/include/__memory_resource/synchronized_pool_resource.h
index 576a29a..cddcd34 100644
--- a/include/__memory_resource/synchronized_pool_resource.h
+++ b/include/__memory_resource/synchronized_pool_resource.h
@@ -14,9 +14,7 @@
 #include <__memory_resource/pool_options.h>
 #include <__memory_resource/unsynchronized_pool_resource.h>
 #include <cstddef>
-#if !defined(_LIBCPP_HAS_NO_THREADS)
-#  include <mutex>
-#endif
+#include <mutex>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
diff --git a/test/libcxx/assertions/headers_declare_verbose_abort.gen.py b/test/libcxx/assertions/headers_declare_verbose_abort.gen.py
index 2bf9b66..f72c257 100644
--- a/test/libcxx/assertions/headers_declare_verbose_abort.gen.py
+++ b/test/libcxx/assertions/headers_declare_verbose_abort.gen.py
@@ -14,22 +14,20 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
     # Skip C compatibility headers.
     if header.endswith('.h'):
         continue
 
-    test_condition_begin = f'#if {header_restrictions[header]}' if header in header_restrictions else ''
-    test_condition_end = '#endif' if header in header_restrictions else ''
-    XFAIL = 'XFAIL' # Make sure Lit doesn't think we are XFAILing this test
+    BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
     print(f"""\
 //--- {header}.compile.pass.cpp
-// {XFAIL}: availability-verbose_abort-missing
-#include <__config>
-{test_condition_begin}
+{lit_header_restrictions.get(header, '')}
+
+// XFAIL{BLOCKLIT}: availability-verbose_abort-missing
+
 #include <{header}>
 using HandlerType = decltype(std::__libcpp_verbose_abort);
-{test_condition_end}
 """)
diff --git a/test/libcxx/clang_tidy.gen.py b/test/libcxx/clang_tidy.gen.py
index 7ced030..a7b8e7b 100644
--- a/test/libcxx/clang_tidy.gen.py
+++ b/test/libcxx/clang_tidy.gen.py
@@ -12,13 +12,10 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
   BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-
   print(f"""\
 //--- {header}.sh.cpp
 
@@ -27,12 +24,11 @@
 // The GCC compiler flags are not always compatible with clang-tidy.
 // UNSUPPORTED{BLOCKLIT}: gcc
 
+{lit_header_restrictions.get(header, '')}
+
 // TODO: run clang-tidy with modules enabled once they are supported
 // RUN{BLOCKLIT}: %{{clang-tidy}} %s --warnings-as-errors=* -header-filter=.* --checks='-*,libcpp-*' --load=%{{test-tools}}/clang_tidy_checks/libcxx-tidy.plugin -- %{{compile_flags}} -fno-modules
 // RUN{BLOCKLIT}: %{{clang-tidy}} %s --warnings-as-errors=* -header-filter=.* --config-file=%{{libcxx}}/.clang-tidy -- -Wweak-vtables %{{compile_flags}} -fno-modules
 
-#include <__config>
-{test_condition_begin}
 #include <{header}>
-{test_condition_end}
 """)
diff --git a/test/libcxx/double_include.gen.py b/test/libcxx/double_include.gen.py
index 10b7be3..ad18121 100644
--- a/test/libcxx/double_include.gen.py
+++ b/test/libcxx/double_include.gen.py
@@ -12,29 +12,22 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
-BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
-print(f"""\
-//--- double_include.sh.cpp
+for header in public_headers:
+  BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
+  print(f"""\
+//--- {header}.sh.cpp
+{lit_header_restrictions.get(header, '')}
+
 // RUN{BLOCKLIT}: %{{cxx}} -c %s -o %t.first.o %{{flags}} %{{compile_flags}}
 // RUN{BLOCKLIT}: %{{cxx}} -c %s -o %t.second.o -DWITH_MAIN %{{flags}} %{{compile_flags}}
 // RUN{BLOCKLIT}: %{{cxx}} -o %t.exe %t.first.o %t.second.o %{{flags}} %{{link_flags}}
 // RUN{BLOCKLIT}: %{{run}}
-""")
 
-for header in public_headers:
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-  print(f"""\
-#include <__config>
-{test_condition_begin}
 #include <{header}>
-{test_condition_end}
-""")
 
-print("""
 #if defined(WITH_MAIN)
-int main(int, char**) { return 0; }
+int main(int, char**) {{ return 0; }}
 #endif
 """)
diff --git a/test/libcxx/header_inclusions.gen.py b/test/libcxx/header_inclusions.gen.py
index 3273f01..f41ac27 100644
--- a/test/libcxx/header_inclusions.gen.py
+++ b/test/libcxx/header_inclusions.gen.py
@@ -13,12 +13,9 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers, mandatory_inclusions
+from libcxx.test.header_information import lit_header_restrictions, public_headers, mandatory_inclusions
 
 for header in public_headers:
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-
   header_guard = lambda h: f"_LIBCPP_{h.upper().replace('.', '_').replace('/', '_')}"
 
   # <cassert> has no header guards
@@ -39,9 +36,8 @@
 
   print(f"""\
 //--- {header}.compile.pass.cpp
-#include <__config>
-{test_condition_begin}
+{lit_header_restrictions.get(header, '')}
+
 #include <{header}>
 {checks}
-{test_condition_end}
 """)
diff --git a/test/libcxx/modules_include.gen.py b/test/libcxx/modules_include.gen.py
index 0b9e67a..565def8 100644
--- a/test/libcxx/modules_include.gen.py
+++ b/test/libcxx/modules_include.gen.py
@@ -14,13 +14,10 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
   BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-
   print(f"""\
 //--- {header}.compile.pass.cpp
 // RUN{BLOCKLIT}: %{{cxx}} %s %{{flags}} %{{compile_flags}} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only
@@ -38,8 +35,7 @@
 // TODO: Investigate this failure
 // UNSUPPORTED{BLOCKLIT}: LIBCXX-FREEBSD-FIXME
 
-#include <__config>
-{test_condition_begin}
+{lit_header_restrictions.get(header, '')}
+
 #include <{header}>
-{test_condition_end}
 """)
diff --git a/test/libcxx/nasty_macros.gen.py b/test/libcxx/nasty_macros.gen.py
index 3308b0b..3d3868f 100644
--- a/test/libcxx/nasty_macros.gen.py
+++ b/test/libcxx/nasty_macros.gen.py
@@ -13,14 +13,13 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-
   print(f"""\
 //--- {header}.compile.pass.cpp
+{lit_header_restrictions.get(header, '')}
+
 #define NASTY_MACRO This should not be expanded!!!
 
 // libc++ does not use single-letter names as a matter of principle.
@@ -150,8 +149,5 @@
 #define min NASTY_MACRO
 #define max NASTY_MACRO
 
-#include <__config>
-{test_condition_begin}
 #include <{header}>
-{test_condition_end}
 """)
diff --git a/test/libcxx/no_assert_include.gen.py b/test/libcxx/no_assert_include.gen.py
index 900cf3e..45152a3 100644
--- a/test/libcxx/no_assert_include.gen.py
+++ b/test/libcxx/no_assert_include.gen.py
@@ -13,23 +13,19 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 for header in public_headers:
   if header == 'cassert':
     continue
 
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
-
   print(f"""\
 //--- {header}.compile.pass.cpp
+{lit_header_restrictions.get(header, '')}
 
-#include <__config>
-{test_condition_begin}
 #include <{header}>
+
 #ifdef assert
 # error "Do not include cassert or assert.h in standard header files"
 #endif
-{test_condition_end}
 """)
diff --git a/test/libcxx/private_headers.gen.py b/test/libcxx/private_headers.gen.py
index 541ce20..9091e62 100644
--- a/test/libcxx/private_headers.gen.py
+++ b/test/libcxx/private_headers.gen.py
@@ -13,7 +13,7 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, private_headers, private_headers_still_public_in_modules
+from libcxx.test.header_information import lit_header_restrictions, private_headers, private_headers_still_public_in_modules
 
 for header in private_headers:
   # Skip headers that are not private yet in the modulemap
@@ -32,16 +32,11 @@
   if header.startswith('__pstl'):
     continue
 
-  test_condition_begin = '#if ' + header_restrictions[header] if header in header_restrictions else ''
-  test_condition_end = '#endif' if header in header_restrictions else ''
   BLOCKLIT = '' # block Lit from interpreting a RUN/XFAIL/etc inside the generation script
-
   print(f"""\
 //--- {header}.verify.cpp
 // REQUIRES{BLOCKLIT}: modules-build
+{lit_header_restrictions.get(header, '')}
 
-#include <__config>
-{test_condition_begin}
 #include <{header}> // expected-error@*:* {{{{use of private header from outside its module: '{header}'}}}}
-{test_condition_end}
 """)
diff --git a/test/libcxx/transitive_includes.gen.py b/test/libcxx/transitive_includes.gen.py
index 94ba9a1..13f897b 100644
--- a/test/libcxx/transitive_includes.gen.py
+++ b/test/libcxx/transitive_includes.gen.py
@@ -20,7 +20,7 @@
 
 import sys
 sys.path.append(sys.argv[1])
-from libcxx.test.header_information import header_restrictions, public_headers
+from libcxx.test.header_information import lit_header_restrictions, public_headers
 
 import re
 
@@ -61,10 +61,10 @@
 
     print(f"""\
 //--- {header}.sh.cpp
+{lit_header_restrictions.get(header, '')}
 
-// This test doesn't support being run when some headers are not available, since we
-// would need to add significant complexity to make that work.
-// UNSUPPORTED{BLOCKLIT}: no-localization, no-threads, no-wide-characters, no-filesystem
+// TODO: Fix this test to make it work with filesystem, localization or wide characters disabled
+// UNSUPPORTED{BLOCKLIT}: no-filesystem, no-localization, no-wide-characters
 
 // When built with modules, this test doesn't work because --trace-includes doesn't
 // report the stack of includes correctly.
diff --git a/utils/libcxx/test/header_information.py b/utils/libcxx/test/header_information.py
index af182df..6ebfbb8 100644
--- a/utils/libcxx/test/header_information.py
+++ b/utils/libcxx/test/header_information.py
@@ -8,58 +8,6 @@
 
 import os, pathlib
 
-header_restrictions = {
-    "barrier": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "future": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "latch": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "mutex": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "semaphore": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "shared_mutex": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "stdatomic.h": "__cplusplus > 202002L && !defined(_LIBCPP_HAS_NO_THREADS)",
-    "stop_token": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "thread": "!defined(_LIBCPP_HAS_NO_THREADS)",
-    "filesystem": "!defined(_LIBCPP_HAS_NO_FILESYSTEM_LIBRARY)",
-    # TODO(LLVM-17): simplify this to __cplusplus >= 202002L
-    "coroutine": "(defined(__cpp_impl_coroutine) && __cpp_impl_coroutine >= 201902L) || (defined(__cpp_coroutines) && __cpp_coroutines >= 201703L)",
-    "clocale": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "codecvt": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "fstream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)",
-    "iomanip": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "ios": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "iostream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "istream": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "locale.h": "!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)",
-    "wctype.h": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
-    "cwctype": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
-    "cwchar": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
-    "wchar.h": "!defined(_LIBCPP_HAS_NO_WIDE_CHARACTERS)",
-    "experimental/algorithm": "__cplusplus >= 201103L",
-    "experimental/deque": "__cplusplus >= 201103L",
-    "experimental/forward_list": "__cplusplus >= 201103L",
-    "experimental/functional": "__cplusplus >= 201103L",
-    "experimental/iterator": "__cplusplus >= 201103L",
-    "experimental/list": "__cplusplus >= 201103L",
-    "experimental/map": "__cplusplus >= 201103L",
-    "experimental/memory_resource": "__cplusplus >= 201103L",
-    "experimental/propagate_const": "__cplusplus >= 201103L",
-    "experimental/regex": "!defined(_LIBCPP_HAS_NO_LOCALIZATION) && __cplusplus >= 201103L",
-    "experimental/set": "__cplusplus >= 201103L",
-    "experimental/simd": "__cplusplus >= 201103L",
-    "experimental/span": "__cplusplus >= 201103L",
-    "experimental/string": "__cplusplus >= 201103L",
-    "experimental/type_traits": "__cplusplus >= 201103L",
-    "experimental/unordered_map": "__cplusplus >= 201103L",
-    "experimental/unordered_set": "__cplusplus >= 201103L",
-    "experimental/utility": "__cplusplus >= 201103L",
-    "experimental/vector": "__cplusplus >= 201103L",
-}
-
 lit_header_restrictions = {
     "barrier": "// UNSUPPORTED: no-threads, c++03, c++11, c++14, c++17",
     "stop_token": "// UNSUPPORTED: no-threads, c++03, c++11, c++14, c++17",