diff --git a/clang/lib/Lex/ModuleMap.cpp b/clang/lib/Lex/ModuleMap.cpp
index f39928a..1c5b4e2 100644
--- a/clang/lib/Lex/ModuleMap.cpp
+++ b/clang/lib/Lex/ModuleMap.cpp
@@ -89,7 +89,7 @@
                      HeaderSearch &HeaderInfo)
     : SourceMgr(SourceMgr), Diags(Diags), LangOpts(LangOpts), Target(Target),
       HeaderInfo(HeaderInfo), BuiltinIncludeDir(nullptr),
-      CompilingModule(nullptr), SourceModule(nullptr), NumCreatedModules(0) {
+      SourceModule(nullptr), NumCreatedModules(0) {
   MMapLangOpts.LineComment = true;
 }
 
@@ -343,8 +343,8 @@
     ModuleMap::KnownHeader Result;
     // Iterate over all modules that 'File' is part of to find the best fit.
     for (KnownHeader &H : Known->second) {
-      // Prefer a header from the current module over all others.
-      if (H.getModule()->getTopLevelModule() == CompilingModule)
+      // Prefer a header from the source module over all others.
+      if (H.getModule()->getTopLevelModule() == SourceModule)
         return MakeResult(H);
       if (!Result || isBetterKnownHeader(H, Result))
         Result = H;
@@ -556,16 +556,10 @@
   // Create a new module with this name.
   Module *Result = new Module(Name, SourceLocation(), Parent,
                               IsFramework, IsExplicit, NumCreatedModules++);
-  if (LangOpts.CurrentModule == Name) {
-    SourceModule = Result;
-    SourceModuleName = Name;
-  }
   if (!Parent) {
+    if (LangOpts.CurrentModule == Name)
+      SourceModule = Result;
     Modules[Name] = Result;
-    if (!LangOpts.CurrentModule.empty() && !CompilingModule &&
-        Name == LangOpts.CurrentModule) {
-      CompilingModule = Result;
-    }
   }
   return std::make_pair(Result, true);
 }
@@ -693,9 +687,10 @@
                               NumCreatedModules++);
   InferredModuleAllowedBy[Result] = ModuleMapFile;
   Result->IsInferred = true;
-  if (LangOpts.CurrentModule == ModuleName) {
-    SourceModule = Result;
-    SourceModuleName = ModuleName;
+  if (!Parent) {
+    if (LangOpts.CurrentModule == ModuleName)
+      SourceModule = Result;
+    Modules[ModuleName] = Result;
   }
 
   Result->IsSystem |= Attrs.IsSystem;
@@ -703,9 +698,6 @@
   Result->ConfigMacrosExhaustive |= Attrs.IsExhaustive;
   Result->Directory = FrameworkDir;
 
-  if (!Parent)
-    Modules[ModuleName] = Result;
-  
   // umbrella header "umbrella-header-name"
   //
   // The "Headers/" component of the name is implied because this is
@@ -812,7 +804,8 @@
   HeaderList.push_back(KH);
   Mod->Headers[headerRoleToKind(Role)].push_back(std::move(Header));
 
-  bool isCompilingModuleHeader = Mod->getTopLevelModule() == CompilingModule;
+  bool isCompilingModuleHeader =
+      LangOpts.CompilingModule && Mod->getTopLevelModule() == SourceModule;
   if (!Imported || isCompilingModuleHeader) {
     // When we import HeaderFileInfo, the external source is expected to
     // set the isModuleHeader flag itself.