diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -986,8 +986,13 @@
     // In MinGW, variables without DLLImport can still be automatically
     // imported from a DLL by the linker; don't mark variables that
     // potentially could come from another DLL as DSO local.
+
+    // With EmulatedTLS, TLS variables can be autoimported from other DLLs
+    // (and this actually happens in the public interface of libstdc++), so
+    // such variables can't be marked as DSO local. (Native TLS variables
+    // can't be dllimported at all, though.)
     if (GV->isDeclarationForLinker() && isa<llvm::GlobalVariable>(GV) &&
-        !GV->isThreadLocal())
+        (!GV->isThreadLocal() || CGM.getCodeGenOpts().EmulatedTLS))
       return false;
   }
 
diff --git a/clang/test/CodeGen/dso-local-executable.c b/clang/test/CodeGen/dso-local-executable.c
--- a/clang/test/CodeGen/dso-local-executable.c
+++ b/clang/test/CodeGen/dso-local-executable.c
@@ -9,13 +9,15 @@
 // COFF-DAG: define dso_local i32* @zed()
 // COFF-DAG: declare dllimport void @import_func()
 
-// RUN: %clang_cc1 -triple x86_64-w64-mingw32 -emit-llvm %s -o - | FileCheck --check-prefix=MINGW %s
+// RUN: %clang_cc1 -triple x86_64-w64-mingw32 -emit-llvm %s -o - | FileCheck --check-prefixes=MINGW,MINGW-NATIVE_TLS %s
+// RUN: %clang_cc1 -triple x86_64-w64-mingw32 -emit-llvm %s -o - -femulated-tls | FileCheck --check-prefixes=MINGW,MINGW-EMUTLS %s
 // MINGW:      @baz = dso_local global i32 42
 // MINGW-NEXT: @import_var = external dllimport global i32
 // MINGW-NEXT: @weak_bar = extern_weak global i32
 // MINGW-NEXT: @bar = external global i32
 // MINGW-NEXT: @local_thread_var = dso_local thread_local global i32 42
-// MINGW-NEXT: @thread_var = external dso_local thread_local global i32
+// MINGW-NATIVE_TLS-NEXT: @thread_var = external dso_local thread_local global i32
+// MINGW-EMUTLS-NEXT: @thread_var = external thread_local global i32
 // MINGW-DAG: declare dso_local void @foo()
 // MINGW-DAG: define dso_local i32* @zed()
 // MINGW-DAG: declare dllimport void @import_func()