diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 314eee0..dbba5fd 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1017,6 +1017,7 @@
   RECORD(SUBMODULE_PRIVATE_HEADER);
   RECORD(SUBMODULE_TEXTUAL_HEADER);
   RECORD(SUBMODULE_PRIVATE_TEXTUAL_HEADER);
+  RECORD(SUBMODULE_INITIALIZERS);
 
   // Comments Block.
   BLOCK(COMMENTS_BLOCK);
@@ -2417,7 +2418,9 @@
   if (Known != SubmoduleIDs.end())
     return Known->second;
 
-  if (Mod->getTopLevelModule() != WritingModule)
+  auto *Top = Mod->getTopLevelModule();
+  if (Top != WritingModule &&
+      !Top->fullModuleNameIs(StringRef(getLangOpts().CurrentModule)))
     return 0;
 
   return SubmoduleIDs[Mod] = NextSubmoduleID++;
@@ -2649,6 +2652,13 @@
       Stream.EmitRecordWithBlob(ConfigMacroAbbrev, Record, CM);
     }
 
+    // Emit the initializers, if any.
+    RecordData Inits;
+    for (Decl *D : Context->getModuleInitializers(Mod))
+      Inits.push_back(GetDeclRef(D));
+    if (!Inits.empty())
+      Stream.EmitRecord(SUBMODULE_INITIALIZERS, Inits);
+
     // Queue up the submodules of this module.
     for (auto *M : Mod->submodules())
       Q.push(M);
@@ -4514,6 +4524,17 @@
   // If we're emitting a module, write out the submodule information.  
   if (WritingModule)
     WriteSubmodules(WritingModule);
+  else if (!getLangOpts().CurrentModule.empty()) {
+    // If we're building a PCH in the implementation of a module, we may need
+    // the description of the current module.
+    //
+    // FIXME: We may need other modules that we did not load from an AST file,
+    // such as if a module declares a 'conflicts' on a different module.
+    Module *M = PP.getHeaderSearchInfo().getModuleMap().findModule(
+        getLangOpts().CurrentModule);
+    if (M && !M->IsFromModuleFile)
+      WriteSubmodules(M);
+  }
 
   Stream.EmitRecord(SPECIAL_TYPES, SpecialTypes);