Index: include/llvm/LinkAllPasses.h
===================================================================
--- include/llvm/LinkAllPasses.h
+++ include/llvm/LinkAllPasses.h
@@ -86,6 +86,7 @@
       (void) llvm::createDomViewerPass();
       (void) llvm::createGCOVProfilerPass();
       (void) llvm::createInstrProfilingPass();
+      (void) llvm::createFunctionImportPass(std::string());
       (void) llvm::createFunctionInliningPass();
       (void) llvm::createAlwaysInlinerPass();
       (void) llvm::createGlobalDCEPass();
Index: include/llvm/Linker/Linker.h
===================================================================
--- include/llvm/Linker/Linker.h
+++ include/llvm/Linker/Linker.h
@@ -90,10 +90,12 @@
 
   static bool LinkModules(Module *Dest, Module *Src,
                           DiagnosticHandlerFunction DiagnosticHandler,
-                          unsigned Flags = Flags::None);
+                          unsigned Flags = Flags::None,
+                          FunctionInfoIndex *Index = nullptr);
 
   static bool LinkModules(Module *Dest, Module *Src,
-                          unsigned Flags = Flags::None);
+                          unsigned Flags = Flags::None,
+                          FunctionInfoIndex *Index = nullptr);
 
 private:
   void init(Module *M, DiagnosticHandlerFunction DiagnosticHandler);
Index: include/llvm/Transforms/IPO.h
===================================================================
--- include/llvm/Transforms/IPO.h
+++ include/llvm/Transforms/IPO.h
@@ -85,6 +85,8 @@
 ModulePass *createGVExtractionPass(std::vector<GlobalValue*>& GVs, bool
                                    deleteFn = false);
 
+ModulePass *createFunctionImportPass(StringRef IndexFile);
+
 //===----------------------------------------------------------------------===//
 /// createFunctionInliningPass - Return a new pass object that uses a heuristic
 /// to inline direct function calls to small functions.
Index: include/llvm/Transforms/IPO/PassManagerBuilder.h
===================================================================
--- include/llvm/Transforms/IPO/PassManagerBuilder.h
+++ include/llvm/Transforms/IPO/PassManagerBuilder.h
@@ -15,6 +15,7 @@
 #ifndef LLVM_TRANSFORMS_IPO_PASSMANAGERBUILDER_H
 #define LLVM_TRANSFORMS_IPO_PASSMANAGERBUILDER_H
 
+#include <string>
 #include <vector>
 
 namespace llvm {
@@ -114,6 +115,9 @@
   /// added to the per-module passes.
   Pass *Inliner;
 
+  /// The function summary index file to use for function importing.
+  std::string FunctionImportIndexFile;
+
   bool DisableTailCalls;
   bool DisableUnitAtATime;
   bool DisableUnrollLoops;
Index: lib/Linker/LinkModules.cpp
===================================================================
--- lib/Linker/LinkModules.cpp
+++ lib/Linker/LinkModules.cpp
@@ -2113,14 +2113,15 @@
 /// relied on to be consistent.
 bool Linker::LinkModules(Module *Dest, Module *Src,
                          DiagnosticHandlerFunction DiagnosticHandler,
-                         unsigned Flags) {
+                         unsigned Flags, FunctionInfoIndex *Index) {
   Linker L(Dest, DiagnosticHandler);
-  return L.linkInModule(Src, Flags);
+  return L.linkInModule(Src, Flags, Index);
 }
 
-bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags) {
+bool Linker::LinkModules(Module *Dest, Module *Src, unsigned Flags,
+                         FunctionInfoIndex *Index) {
   Linker L(Dest);
-  return L.linkInModule(Src, Flags);
+  return L.linkInModule(Src, Flags, Index);
 }
 
 //===----------------------------------------------------------------------===//
Index: lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- lib/Transforms/IPO/FunctionImport.cpp
+++ lib/Transforms/IPO/FunctionImport.cpp
@@ -239,22 +239,36 @@
 
 /// Pass that performs cross-module function import provided a summary file.
 class FunctionImportPass : public ModulePass {
+  /// File holding the function summary index for import
+  StringRef IndexFile;
 
 public:
   /// Pass identification, replacement for typeid
   static char ID;
 
-  explicit FunctionImportPass() : ModulePass(ID) {}
+  /// Specify pass name for debug output
+  const char *getPassName() const override {
+    return "Function Importing";
+  }
 
-  bool runOnModule(Module &M) override {
-    if (SummaryFile.empty()) {
-      report_fatal_error("error: -function-import requires -summary-file\n");
+  explicit FunctionImportPass(StringRef IndexFileName = "")
+      : ModulePass(ID), IndexFile(IndexFileName) {
+    if (!SummaryFile.empty()) {
+      if (!IndexFile.empty())
+        report_fatal_error("error: -summary-file and file from frontend\n");
+      IndexFile = SummaryFile;
     }
+    if (IndexFile.empty())
+      report_fatal_error("error: -function-import requires -summary-file or "
+                         "file from frontend\n");
+  }
+
+  bool runOnModule(Module &M) override {
     std::string Error;
     std::unique_ptr<FunctionInfoIndex> Index =
-        getFunctionIndexForFile(SummaryFile, Error, diagnosticHandler);
+        getFunctionIndexForFile(IndexFile, Error, diagnosticHandler);
     if (!Index) {
-      errs() << "Error loading file '" << SummaryFile << "': " << Error << "\n";
+      errs() << "Error loading file '" << IndexFile << "': " << Error << "\n";
       return false;
     }
 
@@ -273,5 +287,7 @@
                     "Summary Based Function Import", false, false)
 
 namespace llvm {
-Pass *createFunctionImportPass() { return new FunctionImportPass(); }
+Pass *createFunctionImportPass(StringRef IndexFile) {
+  return new FunctionImportPass(IndexFile);
+}
 }
Index: lib/Transforms/IPO/PassManagerBuilder.cpp
===================================================================
--- lib/Transforms/IPO/PassManagerBuilder.cpp
+++ lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -476,6 +476,9 @@
   // Provide AliasAnalysis services for optimizations.
   addInitialAliasAnalysisPasses(PM);
 
+  if (!FunctionImportIndexFile.empty())
+    PM.add(createFunctionImportPass(FunctionImportIndexFile));
+
   // Propagate constants at call sites into the functions they call.  This
   // opens opportunities for globalopt (and inlining) by substituting function
   // pointers passed as arguments to direct uses of functions.