diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -84,6 +84,8 @@
    the C locale API (e.g. embedded). When localization is not supported,
    several parts of the library will be disabled: <iostream>, <regex>, <locale>
    will be completely unusable, and other parts may be only partly available." ON)
+option(LIBCXX_ENABLE_FSTREAM
+   "Whether to include support for <fstream>." ON) # TODO: Consider rolling that into LIBCXX_ENABLE_FILESYSTEM
 option(LIBCXX_ENABLE_UNICODE
   "Whether to include support for Unicode in the library. Disabling Unicode can
    be useful when porting to platforms that don't support UTF-8 encoding (e.g.
@@ -860,6 +862,7 @@
 config_define_if_not(LIBCXX_ENABLE_FILESYSTEM _LIBCPP_HAS_NO_FILESYSTEM_LIBRARY)
 config_define_if_not(LIBCXX_ENABLE_RANDOM_DEVICE _LIBCPP_HAS_NO_RANDOM_DEVICE)
 config_define_if_not(LIBCXX_ENABLE_LOCALIZATION _LIBCPP_HAS_NO_LOCALIZATION)
+config_define_if_not(LIBCXX_ENABLE_FSTREAM _LIBCPP_HAS_NO_FSTREAM)
 config_define_if_not(LIBCXX_ENABLE_UNICODE _LIBCPP_HAS_NO_UNICODE)
 config_define_if_not(LIBCXX_ENABLE_WIDE_CHARACTERS _LIBCPP_HAS_NO_WIDE_CHARACTERS)
 config_define_if_not(LIBCXX_ENABLE_VENDOR_AVAILABILITY_ANNOTATIONS _LIBCPP_HAS_NO_VENDOR_AVAILABILITY_ANNOTATIONS)
diff --git a/libcxx/cmake/caches/Generic-no-fstream.cmake b/libcxx/cmake/caches/Generic-no-fstream.cmake
new file mode 100644
--- /dev/null
+++ b/libcxx/cmake/caches/Generic-no-fstream.cmake
@@ -0,0 +1 @@
+set(LIBCXX_ENABLE_FSTREAM OFF CACHE BOOL "")
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -838,7 +838,7 @@
   wctype.h
   )
 
-foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)
+foreach(feature LIBCXX_ENABLE_FILESYSTEM LIBCXX_ENABLE_LOCALIZATION LIBCXX_ENABLE_FSTREAM LIBCXX_ENABLE_THREADS LIBCXX_ENABLE_WIDE_CHARACTERS)
   if (NOT ${${feature}})
     set(requires_${feature} "requires LIBCXX_CONFIGURED_WITHOUT_SUPPORT_FOR_THIS_HEADER")
   endif()
diff --git a/libcxx/include/__config_site.in b/libcxx/include/__config_site.in
--- a/libcxx/include/__config_site.in
+++ b/libcxx/include/__config_site.in
@@ -28,6 +28,7 @@
 #cmakedefine _LIBCPP_HAS_PARALLEL_ALGORITHMS
 #cmakedefine _LIBCPP_HAS_NO_RANDOM_DEVICE
 #cmakedefine _LIBCPP_HAS_NO_LOCALIZATION
+#cmakedefine _LIBCPP_HAS_NO_FSTREAM
 #cmakedefine _LIBCPP_HAS_NO_WIDE_CHARACTERS
 #cmakedefine01 _LIBCPP_ENABLE_ASSERTIONS_DEFAULT
 #cmakedefine _LIBCPP_ENABLE_DEBUG_MODE
diff --git a/libcxx/include/fstream b/libcxx/include/fstream
--- a/libcxx/include/fstream
+++ b/libcxx/include/fstream
@@ -210,6 +210,8 @@
 #  define _LIBCPP_HAS_NO_OFF_T_FUNCTIONS
 #endif
 
+#if !defined(_LIBCPP_HAS_NO_FSTREAM)
+
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template <class _CharT, class _Traits>
@@ -1742,6 +1744,8 @@
 
 _LIBCPP_END_NAMESPACE_STD
 
+#endif // _LIBCPP_HAS_NO_FSTREAM
+
 _LIBCPP_POP_MACROS
 
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -855,6 +855,7 @@
   }
   module fstream {
     @requires_LIBCXX_ENABLE_LOCALIZATION@
+    @requires_LIBCXX_ENABLE_FSTREAM@
     header "fstream"
     export *
   }
diff --git a/libcxx/src/ios.instantiations.cpp b/libcxx/src/ios.instantiations.cpp
--- a/libcxx/src/ios.instantiations.cpp
+++ b/libcxx/src/ios.instantiations.cpp
@@ -36,9 +36,12 @@
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_stringstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostringstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istringstream<char>;
+
+#ifndef _LIBCPP_HAS_NO_FSTREAM
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ifstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ofstream<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_filebuf<char>;
+#endif
 
 // Add more here if needed...
 
diff --git a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
--- a/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
+++ b/libcxx/test/libcxx/assertions/headers_declare_verbose_abort.sh.cpp
@@ -325,7 +325,7 @@
 #endif
 
 // RUN: %{build} -DTEST_51
-#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
     using HandlerType = decltype(std::__libcpp_verbose_abort);
 #endif
diff --git a/libcxx/test/libcxx/clang_tidy.sh.cpp b/libcxx/test/libcxx/clang_tidy.sh.cpp
--- a/libcxx/test/libcxx/clang_tidy.sh.cpp
+++ b/libcxx/test/libcxx/clang_tidy.sh.cpp
@@ -98,7 +98,7 @@
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/double_include.sh.cpp b/libcxx/test/libcxx/double_include.sh.cpp
--- a/libcxx/test/libcxx/double_include.sh.cpp
+++ b/libcxx/test/libcxx/double_include.sh.cpp
@@ -100,7 +100,7 @@
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/min_max_macros.compile.pass.cpp
@@ -151,7 +151,7 @@
 TEST_MACROS();
 #include <forward_list>
 TEST_MACROS();
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 TEST_MACROS();
 #endif
diff --git a/libcxx/test/libcxx/modules_include.sh.cpp b/libcxx/test/libcxx/modules_include.sh.cpp
--- a/libcxx/test/libcxx/modules_include.sh.cpp
+++ b/libcxx/test/libcxx/modules_include.sh.cpp
@@ -251,7 +251,7 @@
 #include <forward_list>
 #endif
 // RUN: %{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_51
-#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if defined(TEST_51) && !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #include <fstream>
 #endif
 // RUN: %{cxx} %s %{flags} %{compile_flags} -fmodules -fcxx-modules -fmodules-cache-path=%t -fsyntax-only -DTEST_52
diff --git a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
--- a/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
+++ b/libcxx/test/libcxx/nasty_macros.compile.pass.cpp
@@ -219,7 +219,7 @@
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
--- a/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
+++ b/libcxx/test/libcxx/no_assert_include.compile.pass.cpp
@@ -97,7 +97,7 @@
 #include <float.h>
 #include <format>
 #include <forward_list>
-#if !defined(_LIBCPP_HAS_NO_LOCALIZATION)
+#if !defined(_LIBCPP_HAS_NO_LOCALIZATION) && !defined(_LIBCPP_HAS_NO_FSTREAM)
 #   include <fstream>
 #endif
 #include <functional>
diff --git a/libcxx/test/std/input.output/file.streams/lit.local.cfg b/libcxx/test/std/input.output/file.streams/lit.local.cfg
--- a/libcxx/test/std/input.output/file.streams/lit.local.cfg
+++ b/libcxx/test/std/input.output/file.streams/lit.local.cfg
@@ -1,3 +1,6 @@
 # All non-trivial uses of iostreams require localization support
 if 'no-localization' in config.available_features:
   config.unsupported = True
+
+if 'no-fstream' in config.available_features:
+  config.unsupported = True
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.PR14074.pass.cpp
@@ -17,6 +17,8 @@
 // basic_streambuf, but I can't seem to reproduce without going through one
 // of its derived classes.
 
+// UNSUPPORTED: no-fstream
+
 #include <cassert>
 #include <cstddef>
 #include <cstdio>
diff --git a/libcxx/utils/ci/buildkite-pipeline.yml b/libcxx/utils/ci/buildkite-pipeline.yml
--- a/libcxx/utils/ci/buildkite-pipeline.yml
+++ b/libcxx/utils/ci/buildkite-pipeline.yml
@@ -520,6 +520,23 @@
             limit: 2
       timeout_in_minutes: 120
 
+    - label: "No fstream"
+      command: "libcxx/utils/ci/run-buildbot generic-no-fstream"
+      artifact_paths:
+        - "**/test-results.xml"
+        - "**/*.abilist"
+      env:
+          CC: "clang-${LLVM_HEAD_VERSION}"
+          CXX: "clang++-${LLVM_HEAD_VERSION}"
+      agents:
+        queue: "libcxx-builders"
+        os: "linux"
+      retry:
+        automatic:
+          - exit_status: -1  # Agent was lost
+            limit: 2
+      timeout_in_minutes: 120
+
     - label: "No locale"
       command: "libcxx/utils/ci/run-buildbot generic-no-localization"
       artifact_paths:
diff --git a/libcxx/utils/ci/run-buildbot b/libcxx/utils/ci/run-buildbot
--- a/libcxx/utils/ci/run-buildbot
+++ b/libcxx/utils/ci/run-buildbot
@@ -334,6 +334,11 @@
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-random_device.cmake"
     check-runtimes
 ;;
+generic-no-fstream)
+    clean
+    generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-fstream.cmake"
+    check-runtimes
+;;
 generic-no-localization)
     clean
     generate-cmake -C "${MONOREPO_ROOT}/libcxx/cmake/caches/Generic-no-localization.cmake"
diff --git a/libcxx/utils/generate_header_tests.py b/libcxx/utils/generate_header_tests.py
--- a/libcxx/utils/generate_header_tests.py
+++ b/libcxx/utils/generate_header_tests.py
@@ -21,7 +21,7 @@
 
     "clocale": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
     "codecvt": "!defined(_LIBCPP_HAS_NO_LOCALIZATION)",
-    "fstream": "!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)",
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -206,6 +206,7 @@
   '_LIBCPP_HAS_NO_FILESYSTEM_LIBRARY': 'no-filesystem',
   '_LIBCPP_HAS_NO_RANDOM_DEVICE': 'no-random-device',
   '_LIBCPP_HAS_NO_LOCALIZATION': 'no-localization',
+  '_LIBCPP_HAS_NO_FSTREAM': 'no-fstream',
   '_LIBCPP_HAS_NO_WIDE_CHARACTERS': 'no-wide-characters',
   '_LIBCPP_HAS_NO_UNICODE': 'libcpp-has-no-unicode',
   '_LIBCPP_ENABLE_DEBUG_MODE': 'libcpp-has-debug-mode',