diff --git a/llvm/lib/IR/AutoUpgrade.cpp b/llvm/lib/IR/AutoUpgrade.cpp
--- a/llvm/lib/IR/AutoUpgrade.cpp
+++ b/llvm/lib/IR/AutoUpgrade.cpp
@@ -32,12 +32,18 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Verifier.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/Regex.h"
 #include "llvm/TargetParser/Triple.h"
 #include <cstring>
+
 using namespace llvm;
 
+static cl::opt<bool>
+    DisableAutoUpgradeDebugInfo("disable-auto-upgrade-debug-info",
+                                cl::desc("Disable autoupgrade of debug info"));
+
 static void rename(GlobalValue *GV) { GV->setName(GV->getName() + ".old"); }
 
 // Upgrade the declarations of the SSE4.1 ptest intrinsics whose arguments have
@@ -4480,6 +4486,9 @@
 /// Check the debug info version number, if it is out-dated, drop the debug
 /// info. Return true if module is modified.
 bool llvm::UpgradeDebugInfo(Module &M) {
+  if (DisableAutoUpgradeDebugInfo)
+    return false;
+
   unsigned Version = getDebugMetadataVersionFromModule(M);
   if (Version == DEBUG_METADATA_VERSION) {
     bool BrokenDebugInfo = false;
@@ -4988,7 +4997,6 @@
 }
 
 void llvm::UpgradeOperandBundles(std::vector<OperandBundleDef> &Bundles) {
-
   // clang.arc.attachedcall bundles are now required to have an operand.
   // If they don't, it's okay to drop them entirely: when there is an operand,
   // the "attachedcall" is meaningful and required, but without an operand,
diff --git a/llvm/test/LTO/X86/strip-debug-info.ll b/llvm/test/LTO/X86/strip-debug-info.ll
--- a/llvm/test/LTO/X86/strip-debug-info.ll
+++ b/llvm/test/LTO/X86/strip-debug-info.ll
@@ -24,10 +24,18 @@
 ; RUN:     -exported-symbol foo -exported-symbol _foo \
 ; RUN:     %t-stripped.bc -disable-verify 2>&1 | \
 ; RUN:     FileCheck %s -allow-empty -check-prefix=CHECK-WARN
+; ---- Thin LTO (optimize, don't strip imported file)
+; RUN: llvm-lto -thinlto-action=thinlink -o %t.index.bc %t-stripped.bc %t2.bc
+; RUN: llvm-lto -thinlto -thinlto-action=import -disable-auto-upgrade-debug-info \
+; RUN:     -thinlto-index=%t.index.bc \
+; RUN:     -exported-symbol foo -exported-symbol _foo \
+; RUN:     %t-stripped.bc -disable-verify 2>&1 | \
+; RUN:     FileCheck %s -allow-empty -check-prefix=CHECK-NO-WARN
 
 ; CHECK-WARN: warning{{.*}} ignoring invalid debug info
 ; CHECK-WARN-NOT: Broken module found
 ; CHECK: foo
+; CHECK-NO-WARN-NOT: ignoring invalid debug info
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.12"