diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -1366,8 +1366,13 @@
           LLVM_DEBUG(dbgs() << "Skipping due to debug counter\n");
           continue;
         }
-        if (auto *I = dyn_cast<Instruction>(V))
-          I->andIRFlags(&Inst);
+        if (auto *I = dyn_cast<Instruction>(V)) {
+          if (programUndefinedIfPoison(I)) {
+            // Keep poison generating flags, if I being poison is UB.
+            I->andNonPoisonGeneratingIRFlags(&Inst);
+          } else
+            I->andIRFlags(&Inst);
+        }
         Inst.replaceAllUsesWith(V);
         salvageKnowledge(&Inst, &AC);
         removeMSSA(Inst);
diff --git a/llvm/test/Transforms/EarlyCSE/flags.ll b/llvm/test/Transforms/EarlyCSE/flags.ll
--- a/llvm/test/Transforms/EarlyCSE/flags.ll
+++ b/llvm/test/Transforms/EarlyCSE/flags.ll
@@ -22,7 +22,7 @@
 
 define void @test_inbounds_program_ub_if_first_gep_poison(i8* %ptr, i64 %n) {
 ; CHECK-LABEL: @test_inbounds_program_ub_if_first_gep_poison(
-; CHECK-NEXT:    [[ADD_PTR_1:%.*]] = getelementptr i8, i8* [[PTR:%.*]], i64 [[N:%.*]]
+; CHECK-NEXT:    [[ADD_PTR_1:%.*]] = getelementptr inbounds i8, i8* [[PTR:%.*]], i64 [[N:%.*]]
 ; CHECK-NEXT:    call void @use.i8(i8* noundef [[ADD_PTR_1]])
 ; CHECK-NEXT:    call void @use.i8(i8* [[ADD_PTR_1]])
 ; CHECK-NEXT:    ret void