3 files changed, 25 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
index bf6cce96f49..479816a339d 100644
--- a/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
+++ b/llvm/lib/Transforms/Utils/FunctionImportUtils.cpp
@@ -206,8 +206,11 @@ void FunctionImportGlobalProcessing::processGlobalForThinLTO(GlobalValue &GV) {
   // definition.
   if (GV.hasName()) {
     ValueInfo VI = ImportIndex.getValueInfo(GV.getGUID());
-    if (VI && VI.isDSOLocal())
+    if (VI && VI.isDSOLocal()) {
       GV.setDSOLocal(true);
+      if (GV.hasDLLImportStorageClass())
+        GV.setDLLStorageClass(GlobalValue::DefaultStorageClass);
+    }
   }
 
   bool DoPromote = false;
diff --git a/llvm/test/ThinLTO/X86/Inputs/dsolocal_dllimport.ll b/llvm/test/ThinLTO/X86/Inputs/dsolocal_dllimport.ll
new file mode 100644
index 00000000000..5e08d9812db
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/Inputs/dsolocal_dllimport.ll
@@ -0,0 +1,5 @@
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.11.0"
+define dso_local dllexport i32 @foo() {
+  ret i32 42
+}
diff --git a/llvm/test/ThinLTO/X86/dsolocal_dllimport.ll b/llvm/test/ThinLTO/X86/dsolocal_dllimport.ll
new file mode 100644
index 00000000000..12f097f3949
--- /dev/null
+++ b/llvm/test/ThinLTO/X86/dsolocal_dllimport.ll
@@ -0,0 +1,16 @@
+; RUN: opt -module-summary %s -o %t1.bc
+; RUN: opt -module-summary %S/Inputs/dsolocal_dllimport.ll -o %t2.bc
+; RUN: llvm-lto2 run %t1.bc %t2.bc -o %t -r=%t1.bc,bar,px -r=%t1.bc,__imp_foo, -r=%t2.bc,foo -save-temps
+; RUN: llvm-dis < %t.1.3.import.bc | FileCheck %s
+
+; If a user (dllimport) is LTOed with a library, check that we replace dllimport with dso_local.
+
+; CHECK: declare dso_local void @foo()
+
+target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-pc-windows-msvc19.11.0"
+define void @bar() {
+  call void @foo()
+  ret void
+}
+declare dllimport void @foo()