diff --git a/clang/include/clang/Basic/Module.h b/clang/include/clang/Basic/Module.h
--- a/clang/include/clang/Basic/Module.h
+++ b/clang/include/clang/Basic/Module.h
@@ -741,16 +741,11 @@
   using submodule_iterator = std::vector<Module *>::iterator;
   using submodule_const_iterator = std::vector<Module *>::const_iterator;
 
-  submodule_iterator submodule_begin() { return SubModules.begin(); }
-  submodule_const_iterator submodule_begin() const {return SubModules.begin();}
-  submodule_iterator submodule_end()   { return SubModules.end(); }
-  submodule_const_iterator submodule_end() const { return SubModules.end(); }
-
   llvm::iterator_range<submodule_iterator> submodules() {
-    return llvm::make_range(submodule_begin(), submodule_end());
+    return llvm::make_range(SubModules.begin(), SubModules.end());
   }
   llvm::iterator_range<submodule_const_iterator> submodules() const {
-    return llvm::make_range(submodule_begin(), submodule_end());
+    return llvm::make_range(SubModules.begin(), SubModules.end());
   }
 
   /// Appends this module's list of exported modules to \p Exported.
diff --git a/clang/lib/Basic/Module.cpp b/clang/lib/Basic/Module.cpp
--- a/clang/lib/Basic/Module.cpp
+++ b/clang/lib/Basic/Module.cpp
@@ -59,9 +59,8 @@
 }
 
 Module::~Module() {
-  for (submodule_iterator I = submodule_begin(), IEnd = submodule_end();
-       I != IEnd; ++I) {
-    delete *I;
+  for (auto *Submodule: SubModules) {
+    delete Submodule;
   }
 }
 
@@ -339,11 +338,9 @@
 
     Current->IsAvailable = false;
     Current->IsUnimportable |= Unimportable;
-    for (submodule_iterator Sub = Current->submodule_begin(),
-                         SubEnd = Current->submodule_end();
-         Sub != SubEnd; ++Sub) {
-      if (needUpdate(*Sub))
-        Stack.push_back(*Sub);
+    for(auto *Submodule: Current->submodules()){
+      if (needUpdate(Submodule))
+        Stack.push_back(Submodule);
     }
   }
 }
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -6536,16 +6536,14 @@
         EmitTopLevelDecl(D);
 
       // Visit the submodules of this module.
-      for (clang::Module::submodule_iterator Sub = Mod->submodule_begin(),
-                                             SubEnd = Mod->submodule_end();
-           Sub != SubEnd; ++Sub) {
+      for (auto *Submodule : Mod->submodules()) {
         // Skip explicit children; they need to be explicitly imported to emit
         // the initializers.
-        if ((*Sub)->IsExplicit)
+        if (Submodule->IsExplicit)
           continue;
 
-        if (Visited.insert(*Sub).second)
-          Stack.push_back(*Sub);
+        if (Visited.insert(Submodule).second)
+          Stack.push_back(Submodule);
       }
     }
     break;
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -605,8 +605,9 @@
           Module *Current = Stack.pop_back_val();
           if (Current->IsUnimportable) continue;
           Current->IsAvailable = true;
-          Stack.insert(Stack.end(),
-                       Current->submodule_begin(), Current->submodule_end());
+          auto SubmodulesRange = Current->submodules();
+          Stack.insert(Stack.end(), SubmodulesRange.begin(),
+                       SubmodulesRange.end());
         }
       }
     }
diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -429,11 +429,9 @@
   }
 
   // Recurse into submodules.
-  for (clang::Module::submodule_iterator Sub = Module->submodule_begin(),
-                                      SubEnd = Module->submodule_end();
-       Sub != SubEnd; ++Sub)
+  for (auto *Submodule : Module->submodules())
     if (std::error_code Err = collectModuleHeaderIncludes(
-            LangOpts, FileMgr, Diag, ModMap, *Sub, Includes))
+            LangOpts, FileMgr, Diag, ModMap, Submodule, Includes))
       return Err;
 
   return std::error_code();
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -4309,15 +4309,12 @@
                                         /*IsInclusionDirective=*/false);
     // Enumerate submodules.
     if (Mod) {
-      for (Module::submodule_iterator Sub = Mod->submodule_begin(),
-                                      SubEnd = Mod->submodule_end();
-           Sub != SubEnd; ++Sub) {
-
+      for (auto *Submodule : Mod->submodules()) {
         Builder.AddTypedTextChunk(
-            Builder.getAllocator().CopyString((*Sub)->Name));
+            Builder.getAllocator().CopyString(Submodule->Name));
         Results.AddResult(Result(
             Builder.TakeString(), CCP_Declaration, CXCursor_ModuleImportDecl,
-            (*Sub)->isAvailable() ? CXAvailability_Available
+            Submodule->isAvailable() ? CXAvailability_Available
                                   : CXAvailability_NotAvailable));
       }
     }
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1903,18 +1903,16 @@
         SavedStrings.push_back(FilenameDup.data());
 
         HeaderFileInfoTrait::key_type Key = {
-          FilenameDup, *U.Size, IncludeTimestamps ? *U.ModTime : 0
-        };
+            FilenameDup, *U.Size, IncludeTimestamps ? *U.ModTime : 0};
         HeaderFileInfoTrait::data_type Data = {
-          Empty, {}, {M, ModuleMap::headerKindToRole(U.Kind)}
-        };
+            Empty, {}, {M, ModuleMap::headerKindToRole(U.Kind)}};
         // FIXME: Deal with cases where there are multiple unresolved header
         // directives in different submodules for the same header.
         Generator.insert(Key, Data, GeneratorTrait);
         ++NumHeaderSearchEntries;
       }
-
-      Worklist.append(M->submodule_begin(), M->submodule_end());
+      auto SubmodulesRange = M->submodules();
+      Worklist.append(SubmodulesRange.begin(), SubmodulesRange.end());
     }
   }
 
@@ -2701,9 +2699,8 @@
 /// given module).
 static unsigned getNumberOfModules(Module *Mod) {
   unsigned ChildModules = 0;
-  for (auto Sub = Mod->submodule_begin(), SubEnd = Mod->submodule_end();
-       Sub != SubEnd; ++Sub)
-    ChildModules += getNumberOfModules(*Sub);
+  for (auto *Submodule : Mod->submodules())
+    ChildModules += getNumberOfModules(Submodule);
 
   return ChildModules + 1;
 }