Index: lib/LTO/LTO.cpp
===================================================================
--- lib/LTO/LTO.cpp
+++ lib/LTO/LTO.cpp
@@ -291,7 +291,7 @@
         recordNewLinkage) {
   for (auto &S : GVSummaryList) {
     GlobalValue::LinkageTypes OriginalLinkage = S->linkage();
-    if (!GlobalValue::isWeakForLinker(OriginalLinkage))
+    if (GlobalValue::isLocalLinkage(OriginalLinkage))
       continue;
     // We need to emit only one of these. The prevailing module will keep it,
     // but turned into a weak, while the others will drop it when possible.
Index: lib/LTO/ThinLTOCodeGenerator.cpp
===================================================================
--- lib/LTO/ThinLTOCodeGenerator.cpp
+++ lib/LTO/ThinLTOCodeGenerator.cpp
@@ -127,8 +127,16 @@
     return GVSummaryList.size() > 1;
   };
 
+  auto IsAppendingLinkage = [&](const GlobalValueSummaryList &GVSummaryList) {
+    return GVSummaryList.size() > 0 &&
+        GlobalValue::isAppendingLinkage(GVSummaryList[0]->linkage());
+  };
+
   for (auto &I : Index) {
-    if (HasMultipleCopies(I.second.SummaryList))
+    auto &GVSummaryList = I.second.SummaryList;
+    if (HasMultipleCopies(GVSummaryList) &&
+        // There are no non-prevailing copies for symbols with AppendingLinkage
+        !IsAppendingLinkage(GVSummaryList))
       PrevailingCopy[I.first] =
           getFirstDefinitionForLinker(I.second.SummaryList);
   }
Index: lib/Transforms/IPO/FunctionImport.cpp
===================================================================
--- lib/Transforms/IPO/FunctionImport.cpp
+++ lib/Transforms/IPO/FunctionImport.cpp
@@ -911,7 +911,10 @@
       return;
     }
 
-    if (!GlobalValue::isWeakForLinker(GV.getLinkage()))
+    if (GlobalValue::isLocalLinkage(GV.getLinkage()) ||
+        GlobalValue::isAppendingLinkage(GV.getLinkage()) ||
+        // In case it was dead and already converted to declaration.
+        GV.isDeclaration())
       return;
     // Check for a non-prevailing def that has interposable linkage
     // (e.g. non-odr weak or linkonce). In that case we can't simply
Index: test/LTO/Resolution/X86/dead-strip-fulllto.ll
===================================================================
--- test/LTO/Resolution/X86/dead-strip-fulllto.ll
+++ test/LTO/Resolution/X86/dead-strip-fulllto.ll
@@ -1,14 +1,14 @@
 ; RUN: opt -module-summary -o %t %s
 ; RUN: opt -module-summary -o %t2 %S/Inputs/dead-strip-fulllto.ll
 
-; RUN: llvm-lto2 run %t -r %t,main,px -r %t,live1,p -r %t,live2,p -r %t,dead2,p \
-; RUN:               %t2 -r %t2,live1, -r %t2,live2, -r %t2,dead1,p -r %t2,dead2, -r %t2,odr, \
+; RUN: llvm-lto2 run %t -r %t,main,px -r %t,live1, -r %t,live2,p -r %t,dead2,p \
+; RUN:               %t2 -r %t2,live1,p -r %t2,live2, -r %t2,dead1,p -r %t2,dead2, -r %t2,odr, \
 ; RUN: -save-temps -o %t3
 ; RUN: llvm-nm %t3.0 | FileCheck --check-prefix=FULL %s
 ; RUN: llvm-nm %t3.1 | FileCheck --check-prefix=THIN %s
 
-; RUN: llvm-lto2 run %t -r %t,main,px -r %t,live1,p -r %t,live2,p -r %t,dead2,p \
-; RUN:               %t2 -r %t2,live1, -r %t2,live2, -r %t2,dead1,p -r %t2,dead2, -r %t2,odr, \
+; RUN: llvm-lto2 run %t -r %t,main,px -r %t,live1, -r %t,live2,p -r %t,dead2,p \
+; RUN:               %t2 -r %t2,live1,p -r %t2,live2, -r %t2,dead1,p -r %t2,dead2, -r %t2,odr, \
 ; RUN: -save-temps -o %t3 -O0
 ; RUN: llvm-nm %t3.0 | FileCheck --check-prefix=FULL %s
 ; RUN: llvm-nm %t3.1 | FileCheck --check-prefix=THIN %s
Index: test/ThinLTO/X86/Inputs/strong_non_prevailing.ll
===================================================================
--- /dev/null
+++ test/ThinLTO/X86/Inputs/strong_non_prevailing.ll
@@ -0,0 +1,6 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$__llvm_profile_filename = comdat any
+
+@__llvm_profile_filename = constant [19 x i8] c"default_%m.profraw\00", comdat
Index: test/ThinLTO/X86/funcimport.ll
===================================================================
--- test/ThinLTO/X86/funcimport.ll
+++ test/ThinLTO/X86/funcimport.ll
@@ -40,7 +40,7 @@
 ; CODEGEN: T _main
 
 ; Verify that all run together
-; RUN: llvm-lto -thinlto-action=run %t2.bc  %t.bc
+; RUN: llvm-lto -thinlto-action=run %t2.bc  %t.bc -exported-symbol=_main
 ; RUN: llvm-nm -o - < %t.bc.thinlto.o | FileCheck %s --check-prefix=ALL
 ; RUN: llvm-nm -o - < %t2.bc.thinlto.o | FileCheck %s --check-prefix=ALL2
 ; ALL: T _callfuncptr
Index: test/ThinLTO/X86/strong_non_prevailing.ll
===================================================================
--- /dev/null
+++ test/ThinLTO/X86/strong_non_prevailing.ll
@@ -0,0 +1,16 @@
+; RUN: opt -module-summary %s -o %t.bc
+; RUN: opt -module-summary %p/Inputs/strong_non_prevailing.ll -o %t2.bc
+
+; RUN: llvm-lto -thinlto-action=run %t.bc %t2.bc -exported-symbol=__llvm_profile_filename
+; RUN: llvm-nm -o - < %t.bc.thinlto.o | FileCheck %s --check-prefix=EXPORTED
+; RUN: llvm-nm -o - < %t2.bc.thinlto.o 2>&1 | FileCheck %s --check-prefix=NOT_EXPORTED
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$__llvm_profile_filename = comdat any
+
+@__llvm_profile_filename = constant [19 x i8] c"default_%m.profraw\00", comdat
+
+; EXPORTED: N __llvm_profile_filename
+; NOT_EXPORTED-NOT: N __llvm_profile_filename
Index: test/Transforms/FunctionImport/funcimport_var.ll
===================================================================
--- test/Transforms/FunctionImport/funcimport_var.ll
+++ test/Transforms/FunctionImport/funcimport_var.ll
@@ -4,7 +4,7 @@
 ; RUN: opt -module-summary %p/Inputs/funcimport_var2.ll -o %t2.bc
 ; RUN: llvm-lto -thinlto -thinlto-action=thinlink -o %t3 %t.bc %t2.bc
 ; RUN: llvm-lto -thinlto -thinlto-action=import -thinlto-index=%t3 %t.bc %t2.bc
-; RUN: llvm-lto -thinlto -thinlto-action=run %t.bc %t2.bc
+; RUN: llvm-lto -thinlto -thinlto-action=run %t.bc %t2.bc -exported-symbol=_Z4LinkPKcS0_
 ; RUN: llvm-nm %t.bc.thinlto.o | FileCheck %s
 ; RUN: llvm-lto2 run %t.bc %t2.bc -o %t.out \
 ; RUN:   -r %t.bc,_Z4LinkPKcS0_,plx \