Index: cfe/trunk/include/clang/Serialization/ASTReader.h
===================================================================
--- cfe/trunk/include/clang/Serialization/ASTReader.h
+++ cfe/trunk/include/clang/Serialization/ASTReader.h
@@ -821,6 +821,7 @@
   // \brief A list of late parsed template function data.
   SmallVector<uint64_t, 1> LateParsedTemplates;
 
+public:
   struct ImportedSubmodule {
     serialization::SubmoduleID ID;
     SourceLocation ImportLoc;
@@ -829,6 +830,7 @@
       : ID(ID), ImportLoc(ImportLoc) {}
   };
 
+private:
   /// \brief A list of modules that were imported by precompiled headers or
   /// any other non-module AST file.
   SmallVector<ImportedSubmodule, 2> ImportedModules;
@@ -1404,9 +1406,13 @@
   /// \param ClientLoadCapabilities The set of client load-failure
   /// capabilities, represented as a bitset of the enumerators of
   /// LoadFailureCapabilities.
+  ///
+  /// \param Imported optional out-parameter to append the list of modules
+  /// that were imported by precompiled headers or any other non-module AST file
   ASTReadResult ReadAST(StringRef FileName, ModuleKind Type,
                         SourceLocation ImportLoc,
-                        unsigned ClientLoadCapabilities);
+                        unsigned ClientLoadCapabilities,
+                        SmallVectorImpl<ImportedSubmodule> *Imported = nullptr);
 
   /// \brief Make the entities in the given module and any of its (non-explicit)
   /// submodules visible to name lookup.
Index: cfe/trunk/lib/Serialization/ASTReader.cpp
===================================================================
--- cfe/trunk/lib/Serialization/ASTReader.cpp
+++ cfe/trunk/lib/Serialization/ASTReader.cpp
@@ -3578,7 +3578,8 @@
 ASTReader::ASTReadResult ASTReader::ReadAST(StringRef FileName,
                                             ModuleKind Type,
                                             SourceLocation ImportLoc,
-                                            unsigned ClientLoadCapabilities) {
+                                            unsigned ClientLoadCapabilities,
+                                            SmallVectorImpl<ImportedSubmodule> *Imported) {
   llvm::SaveAndRestore<SourceLocation>
     SetCurImportLocRAII(CurrentImportLoc, ImportLoc);
 
@@ -3744,6 +3745,10 @@
   }
   UnresolvedModuleRefs.clear();
 
+  if (Imported)
+    Imported->append(ImportedModules.begin(),
+                     ImportedModules.end());
+
   // FIXME: How do we load the 'use'd modules? They may not be submodules.
   // Might be unnecessary as use declarations are only used to build the
   // module itself.