Index: include/llvm/IR/ModuleSummaryIndex.h
===================================================================
--- include/llvm/IR/ModuleSummaryIndex.h
+++ include/llvm/IR/ModuleSummaryIndex.h
@@ -218,11 +218,18 @@
     /// within the same linkage unit.
     unsigned DSOLocal : 1;
 
+    /// In per-module summary, indicates that the global value is at least
+    /// local unnamed addr.
+    /// In combined summary, indicates that the global value is global unnamed
+    /// addr.
+    unsigned UnnamedAddr : 1;
+
     /// Convenience Constructors
     explicit GVFlags(GlobalValue::LinkageTypes Linkage,
-                     bool NotEligibleToImport, bool Live, bool IsLocal)
+                     bool NotEligibleToImport, bool Live, bool IsLocal,
+                     bool UnnamedAddr)
         : Linkage(Linkage), NotEligibleToImport(NotEligibleToImport),
-          Live(Live), DSOLocal(IsLocal) {}
+          Live(Live), DSOLocal(IsLocal), UnnamedAddr(UnnamedAddr) {}
   };
 
 private:
Index: include/llvm/IR/ModuleSummaryIndexYAML.h
===================================================================
--- include/llvm/IR/ModuleSummaryIndexYAML.h
+++ include/llvm/IR/ModuleSummaryIndexYAML.h
@@ -135,7 +135,7 @@
 
 struct FunctionSummaryYaml {
   unsigned Linkage;
-  bool NotEligibleToImport, Live, IsLocal;
+  bool NotEligibleToImport, Live, IsLocal, UnnamedAddr;
   std::vector<uint64_t> TypeTests;
   std::vector<FunctionSummary::VFuncId> TypeTestAssumeVCalls,
       TypeCheckedLoadVCalls;
@@ -178,6 +178,7 @@
     io.mapOptional("NotEligibleToImport", summary.NotEligibleToImport);
     io.mapOptional("Live", summary.Live);
     io.mapOptional("Local", summary.IsLocal);
+    io.mapOptional("UnnamedAddr", summary.UnnamedAddr);
     io.mapOptional("TypeTests", summary.TypeTests);
     io.mapOptional("TypeTestAssumeVCalls", summary.TypeTestAssumeVCalls);
     io.mapOptional("TypeCheckedLoadVCalls", summary.TypeCheckedLoadVCalls);
@@ -213,7 +214,8 @@
       Elem.SummaryList.push_back(llvm::make_unique<FunctionSummary>(
           GlobalValueSummary::GVFlags(
               static_cast<GlobalValue::LinkageTypes>(FSum.Linkage),
-              FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal),
+              FSum.NotEligibleToImport, FSum.Live, FSum.IsLocal,
+              FSum.UnnamedAddr),
           0, FunctionSummary::FFlags{}, ArrayRef<ValueInfo>{},
           ArrayRef<FunctionSummary::EdgeTy>{}, std::move(FSum.TypeTests),
           std::move(FSum.TypeTestAssumeVCalls),
@@ -231,7 +233,8 @@
               FSum->flags().Linkage,
               static_cast<bool>(FSum->flags().NotEligibleToImport),
               static_cast<bool>(FSum->flags().Live),
-              static_cast<bool>(FSum->flags().DSOLocal), FSum->type_tests(),
+              static_cast<bool>(FSum->flags().DSOLocal), 
+              static_cast<bool>(FSum->flags().UnnamedAddr), FSum->type_tests(),
               FSum->type_test_assume_vcalls(), FSum->type_checked_load_vcalls(),
               FSum->type_test_assume_const_vcalls(),
               FSum->type_checked_load_const_vcalls()});
Index: lib/Analysis/ModuleSummaryAnalysis.cpp
===================================================================
--- lib/Analysis/ModuleSummaryAnalysis.cpp
+++ lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -325,7 +325,8 @@
       // Don't try to import functions with noinline attribute.
       F.getAttributes().hasFnAttribute(Attribute::NoInline);
   GlobalValueSummary::GVFlags Flags(F.getLinkage(), NotEligibleForImport,
-                                    /* Live = */ false, F.isDSOLocal());
+                                    /* Live = */ false, F.isDSOLocal(),
+                                    /* UnnamedAddr= */false);
   FunctionSummary::FFlags FunFlags{
       F.hasFnAttribute(Attribute::ReadNone),
       F.hasFnAttribute(Attribute::ReadOnly),
@@ -351,7 +352,8 @@
   findRefEdges(Index, &V, RefEdges, Visited);
   bool NonRenamableLocal = isNonRenamableLocal(V);
   GlobalValueSummary::GVFlags Flags(V.getLinkage(), NonRenamableLocal,
-                                    /* Live = */ false, V.isDSOLocal());
+                                    /* Live = */ false, V.isDSOLocal(),
+                                    /* UnnamedAddr= */false);
   auto GVarSummary =
       llvm::make_unique<GlobalVarSummary>(Flags, RefEdges.takeVector());
   if (NonRenamableLocal)
@@ -364,7 +366,8 @@
                     DenseSet<GlobalValue::GUID> &CantBePromoted) {
   bool NonRenamableLocal = isNonRenamableLocal(A);
   GlobalValueSummary::GVFlags Flags(A.getLinkage(), NonRenamableLocal,
-                                    /* Live = */ false, A.isDSOLocal());
+                                    /* Live = */ false, A.isDSOLocal(),
+                                    /* UnnamedAddr= */false);
   auto AS = llvm::make_unique<AliasSummary>(Flags);
   auto *Aliasee = A.getBaseObject();
   auto *AliaseeSummary = Index.getGlobalValueSummary(*Aliasee);
@@ -433,7 +436,8 @@
           GlobalValueSummary::GVFlags GVFlags(GlobalValue::InternalLinkage,
                                               /* NotEligibleToImport = */ true,
                                               /* Live = */ true,
-                                              /* Local */ GV->isDSOLocal());
+                                              /* Local */ GV->isDSOLocal(),
+                                              /* UnnamedAddr= */ false);
           CantBePromoted.insert(GlobalValue::getGUID(Name));
           // Create the appropriate summary type.
           if (Function *F = dyn_cast<Function>(GV)) {
Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -891,8 +891,11 @@
   // values as live.
   bool Live = (RawFlags & 0x2) || Version < 3;
   bool Local = (RawFlags & 0x4);
+  // UnnamedAddr flag. Treat as false if not set which is the default behavior.
+  bool UnnamedAddr = (RawFlags & 0x8);
 
-  return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local);
+  return GlobalValueSummary::GVFlags(Linkage, NotEligibleToImport, Live, Local,
+                                     UnnamedAddr);
 }
 
 static GlobalValue::VisibilityTypes getDecodedVisibility(unsigned Val) {
Index: lib/Bitcode/Writer/BitcodeWriter.cpp
===================================================================
--- lib/Bitcode/Writer/BitcodeWriter.cpp
+++ lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -967,6 +967,7 @@
   RawFlags |= Flags.NotEligibleToImport; // bool
   RawFlags |= (Flags.Live << 1);
   RawFlags |= (Flags.DSOLocal << 2);
+  RawFlags |= (Flags.UnnamedAddr << 3);
 
   // Linkage don't need to be remapped at that time for the summary. Any future
   // change to the getEncodedLinkage() function will need to be taken into
Index: test/Transforms/LowerTypeTests/import-unsat.ll
===================================================================
--- test/Transforms/LowerTypeTests/import-unsat.ll
+++ test/Transforms/LowerTypeTests/import-unsat.ll
@@ -8,6 +8,7 @@
 ; SUMMARY-NEXT:      NotEligibleToImport: false
 ; SUMMARY-NEXT:      Live:                true
 ; SUMMARY-NEXT:      Local:               false
+; SUMMARY-NEXT:      UnnamedAddr:         false
 ; SUMMARY-NEXT:      TypeTests: [ 123 ]
 ; SUMMARY-NEXT: TypeIdMap:
 ; SUMMARY-NEXT:   typeid1:
Index: test/Transforms/WholeProgramDevirt/import-indir.ll
===================================================================
--- test/Transforms/WholeProgramDevirt/import-indir.ll
+++ test/Transforms/WholeProgramDevirt/import-indir.ll
@@ -8,6 +8,7 @@
 ; SUMMARY-NEXT:      NotEligibleToImport: false
 ; SUMMARY-NEXT:      Live:                true
 ; SUMMARY-NEXT:      Local:               false
+; SUMMARY-NEXT:      UnnamedAddr:         false
 ; SUMMARY-NEXT:      TypeTestAssumeVCalls:
 ; SUMMARY-NEXT:        - GUID:            123
 ; SUMMARY-NEXT:          Offset:          0