diff --git a/llvm/lib/Transforms/Scalar/DivRemPairs.cpp b/llvm/lib/Transforms/Scalar/DivRemPairs.cpp
--- a/llvm/lib/Transforms/Scalar/DivRemPairs.cpp
+++ b/llvm/lib/Transforms/Scalar/DivRemPairs.cpp
@@ -371,6 +371,11 @@
       Mul->insertAfter(RemInst);
       Sub->insertAfter(Mul);
 
+      // If DivInst has the exact flag, remove it. Otherwise this optimization
+      // may replace a well-defined value 'X % Y' with poison.
+      if (DivInst->hasPoisonGeneratingFlags())
+        DivInst->dropPoisonGeneratingFlags();
+
       // If X can be undef, X should be frozen first.
       // For example, let's assume that Y = 1 & X = undef:
       //   %div = sdiv undef, 1 // %div = undef
diff --git a/llvm/test/Transforms/DivRemPairs/AArch64/div-rem-pairs.ll b/llvm/test/Transforms/DivRemPairs/AArch64/div-rem-pairs.ll
--- a/llvm/test/Transforms/DivRemPairs/AArch64/div-rem-pairs.ll
+++ b/llvm/test/Transforms/DivRemPairs/AArch64/div-rem-pairs.ll
@@ -5,7 +5,7 @@
 ; CHECK-LABEL: @f(
 ; CHECK-NEXT:    [[DOTFROZEN:%.*]] = freeze i8 [[TMP1:%.*]]
 ; CHECK-NEXT:    [[DOTFROZEN1:%.*]] = freeze i8 [[TMP2:%.*]]
-; CHECK-NEXT:    [[TMP4:%.*]] = udiv exact i8 [[DOTFROZEN]], [[DOTFROZEN1]]
+; CHECK-NEXT:    [[TMP4:%.*]] = udiv i8 [[DOTFROZEN]], [[DOTFROZEN1]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = mul i8 [[TMP4]], [[DOTFROZEN1]]
 ; CHECK-NEXT:    [[DOTDECOMPOSED:%.*]] = sub i8 [[DOTFROZEN]], [[TMP5]]
 ; CHECK-NEXT:    store i8 [[DOTDECOMPOSED]], ptr [[TMP0:%.*]], align 1