Index: clang/include/clang/Lex/HeaderSearch.h
===================================================================
--- clang/include/clang/Lex/HeaderSearch.h
+++ clang/include/clang/Lex/HeaderSearch.h
@@ -665,9 +665,13 @@
 
   /// Retrieve all the modules corresponding to the given file.
   ///
+  /// \param AllowCreation Whether to allow inference of a new submodule, or to
+  ///        only return existing known modules.
+  ///
   /// \ref findModuleForHeader should typically be used instead of this.
   ArrayRef<ModuleMap::KnownHeader>
-  findAllModulesForHeader(const FileEntry *File) const;
+  findAllModulesForHeader(const FileEntry *File,
+                          bool AllowCreation = true) const;
 
   /// Read the contents of the given module map file.
   ///
Index: clang/include/clang/Lex/ModuleMap.h
===================================================================
--- clang/include/clang/Lex/ModuleMap.h
+++ clang/include/clang/Lex/ModuleMap.h
@@ -448,9 +448,13 @@
   /// and does not consult the external source. (Those checks are the
   /// responsibility of \ref HeaderSearch.)
   ///
+  /// \param AllowCreation Whether to allow inference of a new submodule, or to
+  ///        only return existing known modules.
+  ///
   /// Typically, \ref findModuleForHeader should be used instead, as it picks
   /// the preferred module for the header.
-  ArrayRef<KnownHeader> findAllModulesForHeader(const FileEntry *File);
+  ArrayRef<KnownHeader> findAllModulesForHeader(const FileEntry *File,
+                                                bool AllowCreation = true);
 
   /// Like \ref findAllModulesForHeader, but do not attempt to infer module
   /// ownership from umbrella headers if we've not already done so.
Index: clang/lib/Lex/HeaderSearch.cpp
===================================================================
--- clang/lib/Lex/HeaderSearch.cpp
+++ clang/lib/Lex/HeaderSearch.cpp
@@ -1565,13 +1565,14 @@
 }
 
 ArrayRef<ModuleMap::KnownHeader>
-HeaderSearch::findAllModulesForHeader(const FileEntry *File) const {
+HeaderSearch::findAllModulesForHeader(const FileEntry *File,
+                                      bool AllowCreation) const {
   if (ExternalSource) {
     // Make sure the external source has handled header info about this file,
     // which includes whether the file is part of a module.
     (void)getExistingFileInfo(File);
   }
-  return ModMap.findAllModulesForHeader(File);
+  return ModMap.findAllModulesForHeader(File, AllowCreation);
 }
 
 static bool suggestModule(HeaderSearch &HS, const FileEntry *File,
Index: clang/lib/Lex/ModuleMap.cpp
===================================================================
--- clang/lib/Lex/ModuleMap.cpp
+++ clang/lib/Lex/ModuleMap.cpp
@@ -683,12 +683,12 @@
 }
 
 ArrayRef<ModuleMap::KnownHeader>
-ModuleMap::findAllModulesForHeader(const FileEntry *File) {
+ModuleMap::findAllModulesForHeader(const FileEntry *File, bool AllowCreation) {
   HeadersMap::iterator Known = findKnownHeader(File);
   if (Known != Headers.end())
     return Known->second;
 
-  if (findOrCreateModuleForHeaderInUmbrellaDir(File))
+  if (AllowCreation && findOrCreateModuleForHeaderInUmbrellaDir(File))
     return Headers.find(File)->second;
 
   return std::nullopt;
Index: clang/lib/Serialization/ASTWriter.cpp
===================================================================
--- clang/lib/Serialization/ASTWriter.cpp
+++ clang/lib/Serialization/ASTWriter.cpp
@@ -185,7 +185,8 @@
     if (!HFI || (HFI->isModuleHeader && !HFI->isCompilingModuleHeader))
       continue;
 
-    for (const auto &KH : HS.findAllModulesForHeader(File)) {
+    for (const auto &KH :
+         HS.findAllModulesForHeader(File, /*AllowCreation=*/false)) {
       if (!KH.getModule())
         continue;
       ModulesToProcess.push_back(KH.getModule());