diff --git a/llvm/unittests/Analysis/ReplaceWithVecLibTest.cpp b/llvm/unittests/Analysis/ReplaceWithVecLibTest.cpp
index a1f0a4a894c8d..95f17f93bf4c0 100644
--- a/llvm/unittests/Analysis/ReplaceWithVecLibTest.cpp
+++ b/llvm/unittests/Analysis/ReplaceWithVecLibTest.cpp
@@ -72,9 +72,11 @@ class ReplaceWithVecLibTest : public ::testing::Test {
     PB.registerFunctionAnalyses(FAM);
 
     // Enable debugging and capture std error
+    bool DebugFlagPrev = llvm::DebugFlag;
     llvm::DebugFlag = true;
     testing::internal::CaptureStderr();
     FPM.run(*M->getFunction("foo"), FAM);
+    llvm::DebugFlag = DebugFlagPrev;
     return getLastLine(testing::internal::GetCapturedStderr());
   }
 };