Index: lib/LTO/ThinLTOCodeGenerator.cpp
===================================================================
--- lib/LTO/ThinLTOCodeGenerator.cpp
+++ lib/LTO/ThinLTOCodeGenerator.cpp
@@ -530,6 +530,7 @@
                                    ModuleSummaryIndex &Index) {
   auto ModuleCount = Index.modulePaths().size();
   auto ModuleIdentifier = TheModule.getModuleIdentifier();
+
   // Collect for each module the list of function it defines (GUID -> Summary).
   StringMap<GVSummaryMapTy> ModuleToDefinedGVSummaries;
   Index.collectDefinedGVSummariesPerModule(ModuleToDefinedGVSummaries);
@@ -547,6 +548,20 @@
   thinLTOResolveWeakForLinkerModule(
       TheModule, ModuleToDefinedGVSummaries[ModuleIdentifier]);
 
+  // Convert the preserved symbols set from string to GUID
+  auto GUIDPreservedSymbols = computeGUIDPreservedSymbols(
+      PreservedSymbols, Triple(TheModule.getTargetTriple()));
+
+  // Promote the exported values in the index, so that they are promoted
+  // in the module.
+  auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
+    const auto &ExportList = ExportLists.find(ModuleIdentifier);
+    return (ExportList != ExportLists.end() &&
+            ExportList->second.count(GUID)) ||
+           GUIDPreservedSymbols.count(GUID);
+  };
+  thinLTOInternalizeAndPromoteInIndex(Index, isExported);
+
   promoteModule(TheModule, Index);
 }
 
Index: lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- lib/Transforms/IPO/FunctionImport.cpp
+++ lib/Transforms/IPO/FunctionImport.cpp
@@ -792,6 +792,17 @@
   ComputeCrossModuleImportForModule(M.getModuleIdentifier(), *Index,
                                     ImportList);
 
+  // Conservatively mark all internal values as promoted. This interface is
+  // only used when doing importing via the function importing pass. The pass
+  // is only enabled when testing importing via the 'opt' tool, which does
+  // not do the ThinLink that would normally determine what values to promote.
+  for (auto &I : *Index) {
+    for (auto &S : I.second) {
+      if (GlobalValue::isLocalLinkage(S->linkage()))
+        S->setLinkage(GlobalValue::ExternalLinkage);
+    }
+  }
+
   // Next we need to promote to global scope and rename any local values that
   // are potentially exported to other modules.
   if (renameModuleForThinLTO(M, *Index, nullptr)) {
Index: lib/Transforms/Utils/FunctionImportUtils.cpp
===================================================================
--- lib/Transforms/Utils/FunctionImportUtils.cpp
+++ lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -72,25 +72,27 @@
   // a summary in the distributed backend case (only summaries for values
   // importes as defs, not references, are included in the index passed
   // to the distributed backends).
+  if (isPerformingImport()) {
+    // We don't know for sure yet if we are importing this value (as either
+    // a reference or a def), since we are simply walking all values in the
+    // module. But by necessity if we end up importing it and it is local,
+    // it must be promoted, so unconditionally promote all values in the
+    // importing module.
+    return true;
+  }
+
+  // When exporting, consult the index.
   auto Summaries = ImportIndex.findGlobalValueSummaryList(SGV->getGUID());
-  if (Summaries == ImportIndex.end())
-    // Assert that this is an import - we should always have access to the
-    // summary when exporting.
-    assert(isPerformingImport() &&
-           "Missing summary for global value when exporting");
-  else {
-    assert(Summaries->second.size() == 1 && "Local has more than one summary");
-    if (Summaries->second.front()->noRename()) {
-      assert((isModuleExporting() || !GlobalsToImport->count(SGV)) &&
-             "Imported a non-renamable local value");
-      return false;
-    }
+  assert(Summaries != ImportIndex.end() &&
+         "Missing summary for global value when exporting");
+  assert(Summaries->second.size() == 1 && "Local has more than one summary");
+  auto Linkage = Summaries->second.front()->linkage();
+  if (!GlobalValue::isLocalLinkage(Linkage)) {
+    assert(!Summaries->second.front()->noRename());
+    return true;
   }
 
-  // Eventually we only need to promote functions in the exporting module that
-  // are referenced by a potentially exported function (i.e. one that is in the
-  // summary index).
-  return true;
+  return false;
 }
 
 std::string FunctionImportGlobalProcessing::getName(const GlobalValue *SGV,
Index: test/ThinLTO/X86/alias_import.ll
===================================================================
--- test/ThinLTO/X86/alias_import.ll
+++ test/ThinLTO/X86/alias_import.ll
@@ -14,11 +14,11 @@
 ; PROMOTE-DAG: @globalfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @globalfunc to void (...)*)
 ; PROMOTE-DAG: @globalfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @globalfunc to void (...)*)
 ; PROMOTE-DAG: @globalfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @globalfunc to void (...)*)
-; PROMOTE-DAG: @internalfuncAlias = alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-DAG: @internalfuncWeakAlias = weak alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-DAG: @internalfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-DAG: @internalfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-DAG: @internalfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
+; PROMOTE-DAG: @internalfuncAlias = alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-DAG: @internalfuncWeakAlias = weak alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-DAG: @internalfuncLinkonceAlias = weak alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-DAG: @internalfuncWeakODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-DAG: @internalfuncLinkonceODRAlias = weak_odr alias void (...), bitcast (void ()* @internalfunc to void (...)*)
 ; PROMOTE-DAG: @linkoncefuncAlias = alias void (...), bitcast (void ()* @linkoncefunc to void (...)*)
 ; PROMOTE-DAG: @linkoncefuncWeakAlias = weak alias void (...), bitcast (void ()* @linkoncefunc to void (...)*)
 ; PROMOTE-DAG: @linkoncefuncLinkonceAlias = weak alias void (...), bitcast (void ()* @linkoncefunc to void (...)*)
@@ -45,7 +45,7 @@
 
 ; These will be imported, check the linkage/renaming after promotion
 ; PROMOTE-DAG: define void @globalfunc()
-; PROMOTE-DAG: define hidden void @internalfunc.llvm.0()
+; PROMOTE-DAG: define internal void @internalfunc()
 ; PROMOTE-DAG: define weak_odr void @linkonceODRfunc()
 ; PROMOTE-DAG: define weak_odr void @weakODRfunc()
 ; PROMOTE-DAG: define weak void @linkoncefunc()
@@ -95,11 +95,11 @@
 ; PROMOTE-INTERNALIZE-DAG: @globalfuncLinkonceAlias = internal alias void (...), bitcast (void ()* @globalfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @globalfuncWeakODRAlias = internal alias void (...), bitcast (void ()* @globalfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @globalfuncLinkonceODRAlias = internal alias void (...), bitcast (void ()* @globalfunc to void (...)*)
-; PROMOTE-INTERNALIZE-DAG: @internalfuncAlias = internal alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-INTERNALIZE-DAG: @internalfuncWeakAlias = internal alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-INTERNALIZE-DAG: @internalfuncLinkonceAlias = internal alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-INTERNALIZE-DAG: @internalfuncWeakODRAlias = internal alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
-; PROMOTE-INTERNALIZE-DAG: @internalfuncLinkonceODRAlias = internal alias void (...), bitcast (void ()* @internalfunc.llvm.0 to void (...)*)
+; PROMOTE-INTERNALIZE-DAG: @internalfuncAlias = internal alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-INTERNALIZE-DAG: @internalfuncWeakAlias = internal alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-INTERNALIZE-DAG: @internalfuncLinkonceAlias = internal alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-INTERNALIZE-DAG: @internalfuncWeakODRAlias = internal alias void (...), bitcast (void ()* @internalfunc to void (...)*)
+; PROMOTE-INTERNALIZE-DAG: @internalfuncLinkonceODRAlias = internal alias void (...), bitcast (void ()* @internalfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @linkonceODRfuncAlias = alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @linkonceODRfuncWeakAlias = internal alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @linkonceODRfuncLinkonceAlias = internal alias void (...), bitcast (void ()* @linkonceODRfunc to void (...)*)
@@ -121,7 +121,7 @@
 ; PROMOTE-INTERNALIZE-DAG: @weakfuncWeakODRAlias = internal alias void (...), bitcast (void ()* @weakfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: @weakfuncLinkonceODRAlias = internal alias void (...), bitcast (void ()* @weakfunc to void (...)*)
 ; PROMOTE-INTERNALIZE-DAG: define internal void @globalfunc()
-; PROMOTE-INTERNALIZE-DAG: define internal void @internalfunc.llvm.0()
+; PROMOTE-INTERNALIZE-DAG: define internal void @internalfunc()
 ; PROMOTE-INTERNALIZE-DAG: define internal void @linkonceODRfunc()
 ; PROMOTE-INTERNALIZE-DAG: define internal void @weakODRfunc()
 ; PROMOTE-INTERNALIZE-DAG: define internal void @linkoncefunc()
Index: tools/llvm-link/llvm-link.cpp
===================================================================
--- tools/llvm-link/llvm-link.cpp
+++ tools/llvm-link/llvm-link.cpp
@@ -328,6 +328,16 @@
       }
       auto Index = std::move(IndexOrErr.get());
 
+      // Conservatively mark all internal values as promoted, since this tool
+      // does not do the ThinLink that would normally determine what values to
+      // promote.
+      for (auto &I : *Index) {
+        for (auto &S : I.second) {
+          if (GlobalValue::isLocalLinkage(S->linkage()))
+            S->setLinkage(GlobalValue::ExternalLinkage);
+        }
+      }
+
       // Promotion
       if (renameModuleForThinLTO(*M, *Index))
         return true;