diff --git a/libcxx/include/__algorithm/pstl_replace.h b/libcxx/include/__algorithm/pstl_replace.h
--- a/libcxx/include/__algorithm/pstl_replace.h
+++ b/libcxx/include/__algorithm/pstl_replace.h
@@ -12,6 +12,7 @@
 #include <__algorithm/pstl_backend.h>
 #include <__algorithm/pstl_for_each.h>
 #include <__algorithm/pstl_frontend_dispatch.h>
+#include <__algorithm/pstl_transform.h>
 #include <__config>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
diff --git a/libcxx/include/private_module_attributes.json.in b/libcxx/include/private_module_attributes.json.in
--- a/libcxx/include/private_module_attributes.json.in
+++ b/libcxx/include/private_module_attributes.json.in
@@ -149,6 +149,11 @@
             "__utility/forward.h"
         ]
     },
+    "__algorithm/pstl_stable_sort.h": {
+        "exports": [
+            "__functional/operations.h"
+        ]
+    },
     "__algorithm/ranges_binary_search.h": {
         "exports": [
             "__functional/ranges_operations.h"
@@ -495,6 +500,11 @@
             "@requires_LIBCXX_ENABLE_FILESYSTEM@"
         ]
     },
+    "__filesystem/filesystem_error.h": {
+        "exports": [
+            "*"
+        ]
+    },
     "__filesystem/path.h": {
         "exports": [
             "__functional/hash.h",
@@ -688,6 +698,11 @@
             "__type_traits/type_identity.h"
         ]
     },
+    "__memory_resource/synchronized_pool_resource.h": {
+        "exports": [
+            "*"
+        ]
+    },
     "__mutex": {
         "requires": [
             "@requires_LIBCXX_ENABLE_THREADS@"
diff --git a/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp
--- a/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp
+++ b/libcxx/test/libcxx/strings/char.traits/char.traits.specializations/arbitrary_char_type.deprecated.verify.cpp
@@ -6,6 +6,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+// This should work for modules too, but clang doesn't emit the diagnostics for unknown reasons.
+// UNSUPPORTED: modules-build
+
 // <string>
 
 // template<> struct char_traits<T> for arbitrary T