diff --git a/lib/ClangImporter/ClangIncludePaths.cpp b/lib/ClangImporter/ClangIncludePaths.cpp
index 28be2a1643ae1..4d06e7bb2cb91 100644
--- a/lib/ClangImporter/ClangIncludePaths.cpp
+++ b/lib/ClangImporter/ClangIncludePaths.cpp
@@ -344,7 +344,47 @@ static void getLibStdCxxFileMapping(
       "codecvt",
       // C++17 and newer:
       "any", "charconv", "filesystem", "memory_resource", "optional",
-      "string_view", "variant"};
+      "string_view", "variant", "bits/algorithmfwd.h", "bits/align.h",
+      "bits/alloc_traits.h", "bits/allocated_ptr.h", "bits/allocator.h",
+      "bits/atomic_base.h", "bits/atomic_futex.h",
+      "bits/atomic_lockfree_defines.h", "bits/basic_ios.h",
+      "bits/basic_string.h", "bits/c++0x_warning.h", "bits/char_traits.h",
+      "bits/charconv.h", "bits/codecvt.h", "bits/concept_check.h",
+      "bits/cpp_type_traits.h", "bits/cxxabi_forced.h",
+      "bits/cxxabi_init_exception.h", "bits/enable_special_members.h",
+      "bits/erase_if.h", "bits/exception.h", "bits/exception_defines.h",
+      "bits/exception_ptr.h", "bits/forward_list.h", "bits/fs_dir.h",
+      "bits/fs_fwd.h", "bits/fs_ops.h", "bits/fs_path.h", "bits/functexcept.h",
+      "bits/functional_hash.h", "bits/gslice.h", "bits/gslice_array.h",
+      "bits/hash_bytes.h", "bits/hashtable.h", "bits/hashtable_policy.h",
+      "bits/indirect_array.h", "bits/invoke.h", "bits/ios_base.h",
+      "bits/iterator_concepts.h", "bits/locale_classes.h", "bits/locale_conv.h",
+      "bits/locale_facets.h", "bits/locale_facets_nonio.h", "bits/localefwd.h",
+      "bits/mask_array.h", "bits/max_size_type.h", "bits/memoryfwd.h",
+      "bits/move.h", "bits/nested_exception.h", "bits/node_handle.h",
+      "bits/ostream_insert.h", "bits/parse_numbers.h", "bits/postypes.h",
+      "bits/predefined_ops.h", "bits/ptr_traits.h", "bits/quoted_string.h",
+      "bits/random.h", "bits/range_access.h", "bits/ranges_algo.h",
+      "bits/ranges_algobase.h", "bits/ranges_base.h", "bits/ranges_cmp.h",
+      "bits/ranges_uninitialized.h", "bits/ranges_util.h", "bits/refwrap.h",
+      "bits/shared_ptr.h", "bits/shared_ptr_atomic.h", "bits/shared_ptr_base.h",
+      "bits/slice_array.h", "bits/std_abs.h", "bits/std_function.h",
+      "bits/std_mutex.h", "bits/std_thread.h", "bits/stl_algo.h",
+      "bits/stl_algobase.h", "bits/stl_bvector.h", "bits/stl_construct.h",
+      "bits/stl_deque.h", "bits/stl_function.h", "bits/stl_heap.h",
+      "bits/stl_iterator.h", "bits/stl_iterator_base_funcs.h",
+      "bits/stl_iterator_base_types.h", "bits/stl_list.h", "bits/stl_map.h",
+      "bits/stl_multimap.h", "bits/stl_multiset.h", "bits/stl_numeric.h",
+      "bits/stl_pair.h", "bits/stl_queue.h", "bits/stl_raw_storage_iter.h",
+      "bits/stl_relops.h", "bits/stl_set.h", "bits/stl_stack.h",
+      "bits/stl_tempbuf.h", "bits/stl_tree.h", "bits/stl_uninitialized.h",
+      "bits/stl_vector.h", "bits/stream_iterator.h",
+      "bits/streambuf_iterator.h", "bits/stringfwd.h",
+      "bits/this_thread_sleep.h", "bits/uniform_int_dist.h",
+      "bits/unique_lock.h", "bits/unique_ptr.h", "bits/unordered_map.h",
+      "bits/unordered_set.h", "bits/uses_allocator.h",
+      "bits/uses_allocator_args.h", "bits/valarray_after.h",
+      "bits/valarray_array.h", "bits/valarray_before.h"};
   std::string additionalHeaderDirectives;
   llvm::raw_string_ostream os(additionalHeaderDirectives);
   os << contents.substr(0, headerInjectionPoint);
diff --git a/stdlib/public/Cxx/libstdcxx/libstdcxx.modulemap b/stdlib/public/Cxx/libstdcxx/libstdcxx.modulemap
index a0d95f5946362..4627ffd22307b 100644
--- a/stdlib/public/Cxx/libstdcxx/libstdcxx.modulemap
+++ b/stdlib/public/Cxx/libstdcxx/libstdcxx.modulemap
@@ -82,5 +82,11 @@ module std {
       requires cplusplus
       export *
     }
+
+    module cstdlib {
+      header "cstdlib"
+      requires cplusplus
+      export *
+    }
   }
 }
diff --git a/test/Interop/Cxx/foreign-reference/Inputs/reference-counted.h b/test/Interop/Cxx/foreign-reference/Inputs/reference-counted.h
index c66e58c03c045..fbf410236cc30 100644
--- a/test/Interop/Cxx/foreign-reference/Inputs/reference-counted.h
+++ b/test/Interop/Cxx/foreign-reference/Inputs/reference-counted.h
@@ -2,11 +2,10 @@
 #define TEST_INTEROP_CXX_FOREIGN_REFERENCE_INPUTS_REFERENCE_COUNTED_H
 
 #include <stdlib.h>
+#include <new>
 
 #include "visibility.h"
 
-inline void *operator new(size_t, void *p) { return p; }
-
 SWIFT_BEGIN_NULLABILITY_ANNOTATIONS
 
 static int finalLocalRefCount = 100;
diff --git a/test/Interop/Cxx/stdlib/foundation-and-std-module.swift b/test/Interop/Cxx/stdlib/foundation-and-std-module.swift
new file mode 100644
index 0000000000000..8dcc93b45c710
--- /dev/null
+++ b/test/Interop/Cxx/stdlib/foundation-and-std-module.swift
@@ -0,0 +1,29 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++14 -Xcc -fmodules-cache-path=%t
+// RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++17 -Xcc -fmodules-cache-path=%t
+// RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++20 -Xcc -fmodules-cache-path=%t
+
+// RUN: find %t | %FileCheck %s
+
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++17 -Xcc -fmodules-cache-path=%t -DADD_CXXSTDLIB
+// RUN: %target-swift-frontend %s -c -enable-experimental-cxx-interop -Xcc -std=c++20 -Xcc -fmodules-cache-path=%t -DADD_CXXSTDLIB
+
+// REQUIRES: OS=macosx || OS=linux-gnu
+
+#if canImport(Foundation)
+import Foundation
+#endif
+
+#if ADD_CXXSTDLIB
+import CxxStdlib
+#endif
+
+func test() {
+#if ADD_CXXSTDLIB
+  let _ = std.string()
+#endif
+}
+
+// CHECK: std-{{.*}}.pcm