Index: llvm/include/llvm/Transforms/Utils/FunctionImportUtils.h
===================================================================
--- llvm/include/llvm/Transforms/Utils/FunctionImportUtils.h
+++ llvm/include/llvm/Transforms/Utils/FunctionImportUtils.h
@@ -32,7 +32,7 @@
 
   /// Globals to import from this module, all other functions will be
   /// imported as declarations instead of definitions.
-  DenseSet<const GlobalValue *> *GlobalsToImport;
+  SetVector<GlobalValue *> *GlobalsToImport;
 
   /// Set to true if the given ModuleSummaryIndex contains any functions
   /// from this source module, in which case we must conservatively assume
@@ -85,7 +85,7 @@
 public:
   FunctionImportGlobalProcessing(
       Module &M, const ModuleSummaryIndex &Index,
-      DenseSet<const GlobalValue *> *GlobalsToImport = nullptr)
+      SetVector<GlobalValue *> *GlobalsToImport = nullptr)
       : M(M), ImportIndex(Index), GlobalsToImport(GlobalsToImport) {
     // If we have a ModuleSummaryIndex but no function to import,
     // then this is the primary module being compiled in a ThinLTO
@@ -104,16 +104,15 @@
 
   bool run();
 
-  static bool
-  doImportAsDefinition(const GlobalValue *SGV,
-                       DenseSet<const GlobalValue *> *GlobalsToImport);
+  static bool doImportAsDefinition(const GlobalValue *SGV,
+                                   SetVector<GlobalValue *> *GlobalsToImport);
 };
 
 /// Perform in-place global value handling on the given Module for
 /// exported local functions renamed and promoted for ThinLTO.
 bool renameModuleForThinLTO(
     Module &M, const ModuleSummaryIndex &Index,
-    DenseSet<const GlobalValue *> *GlobalsToImport = nullptr);
+    SetVector<GlobalValue *> *GlobalsToImport = nullptr);
 
 } // End llvm namespace
 
Index: llvm/lib/Linker/LinkModules.cpp
===================================================================
--- llvm/lib/Linker/LinkModules.cpp
+++ llvm/lib/Linker/LinkModules.cpp
@@ -129,8 +129,7 @@
 bool ModuleLinker::doImportAsDefinition(const GlobalValue *SGV) {
   if (!isPerformingImport())
     return false;
-  return FunctionImportGlobalProcessing::doImportAsDefinition(SGV,
-                                                              GlobalsToImport);
+  report_fatal_error("ModuleLinker does not support importing");
 }
 
 static GlobalValue::VisibilityTypes
Index: llvm/lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- llvm/lib/Transforms/IPO/FunctionImport.cpp
+++ llvm/lib/Transforms/IPO/FunctionImport.cpp
@@ -658,8 +658,7 @@
                << DestModule.getModuleIdentifier() << "\n");
   unsigned ImportedCount = 0;
 
-  // Linker that will be used for importing function
-  Linker TheLinker(DestModule);
+  IRMover Mover(DestModule);
   // Do the actual import of functions now, one Module at a time
   std::set<StringRef> ModuleNameOrderedList;
   for (auto &FunctionsToImportPerModule : ImportList) {
@@ -683,7 +682,7 @@
 
     auto &ImportGUIDs = FunctionsToImportPerModule->second;
     // Find the globals to import
-    DenseSet<const GlobalValue *> GlobalsToImport;
+    SetVector<GlobalValue *> GlobalsToImport;
     for (Function &F : *SrcModule) {
       if (!F.hasName())
         continue;
@@ -722,6 +721,12 @@
       }
     }
     for (GlobalAlias &GA : SrcModule->aliases()) {
+      if (FunctionImportGlobalProcessing::doImportAsDefinition(
+              &GA, &GlobalsToImport)) {
+        GlobalsToImport.insert(&GA);
+        continue;
+      }
+
       if (!GA.hasName())
         continue;
       auto GUID = GA.getGUID();
@@ -766,10 +771,9 @@
                << " from " << SrcModule->getSourceFileName() << "\n";
     }
 
-    // Instruct the linker that the client will take care of linkonce resolution
-    unsigned Flags = Linker::Flags::DontForceLinkLinkonceODR;
-
-    if (TheLinker.linkInModule(std::move(SrcModule), Flags, &GlobalsToImport))
+    if (Mover.move(std::move(SrcModule), GlobalsToImport.getArrayRef(),
+                   [](GlobalValue &, IRMover::ValueAdder) {},
+                   /*LinkModuleInlineAsm=*/false, /*IsPerformingImport=*/true))
       report_fatal_error("Function Import: link error");
 
     ImportedCount += GlobalsToImport.size();
Index: llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -21,11 +21,11 @@
 /// Checks if we should import SGV as a definition, otherwise import as a
 /// declaration.
 bool FunctionImportGlobalProcessing::doImportAsDefinition(
-    const GlobalValue *SGV, DenseSet<const GlobalValue *> *GlobalsToImport) {
+    const GlobalValue *SGV, SetVector<GlobalValue *> *GlobalsToImport) {
 
   // For alias, we tie the definition to the base object. Extract it and recurse
   if (auto *GA = dyn_cast<GlobalAlias>(SGV)) {
-    if (GA->hasWeakAnyLinkage())
+    if (GA->isInterposable())
       return false;
     const GlobalObject *GO = GA->getBaseObject();
     if (!GO->hasLinkOnceODRLinkage())
@@ -34,7 +34,7 @@
         GO, GlobalsToImport);
   }
   // Only import the globals requested for importing.
-  if (GlobalsToImport->count(SGV))
+  if (GlobalsToImport->count(const_cast<GlobalValue *>(SGV)))
     return true;
   // Otherwise no.
   return false;
@@ -57,7 +57,8 @@
     return false;
 
   if (isPerformingImport()) {
-    assert((!GlobalsToImport->count(SGV) || !isNonRenamableLocal(*SGV)) &&
+    assert((!GlobalsToImport->count(const_cast<GlobalValue *>(SGV)) ||
+            !isNonRenamableLocal(*SGV)) &&
            "Attempting to promote non-renamable local");
     // 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
@@ -254,9 +255,8 @@
   return false;
 }
 
-bool llvm::renameModuleForThinLTO(
-    Module &M, const ModuleSummaryIndex &Index,
-    DenseSet<const GlobalValue *> *GlobalsToImport) {
+bool llvm::renameModuleForThinLTO(Module &M, const ModuleSummaryIndex &Index,
+                                  SetVector<GlobalValue *> *GlobalsToImport) {
   FunctionImportGlobalProcessing ThinLTOProcessing(M, Index, GlobalsToImport);
   return ThinLTOProcessing.run();
 }