Index: llvm/lib/Transforms/Utils/Local.cpp
===================================================================
--- llvm/lib/Transforms/Utils/Local.cpp
+++ llvm/lib/Transforms/Utils/Local.cpp
@@ -430,6 +430,10 @@
     return true;
   }
 
+  if (CallInst *CI = isFreeCall(I, TLI))
+    if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
+      return C->isNullValue() || isa<UndefValue>(C);
+
   if (!I->willReturn())
     return false;
 
@@ -483,10 +487,6 @@
   if (isAllocLikeFn(I, TLI))
     return true;
 
-  if (CallInst *CI = isFreeCall(I, TLI))
-    if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
-      return C->isNullValue() || isa<UndefValue>(C);
-
   if (auto *Call = dyn_cast<CallBase>(I))
     if (isMathLibCallNoop(Call, TLI))
       return true;
Index: llvm/test/Transforms/InstCombine/free-undef.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InstCombine/free-undef.ll
@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S -o - | FileCheck %s -check-prefix=INSTCOMBINE
+; RUN: opt < %s -instcombine -simplifycfg -S -o - | FileCheck %s -check-prefix=SIMPLIFYCFG
+
+; Function Attrs: mustprogress nounwind uwtable
+define dso_local i32 @_Z4funcv() local_unnamed_addr {
+; CHECK-LABEL: @_Z4funcv(
+;
+; INSTCOMBINE-LABEL: @_Z4funcv(
+; INSTCOMBINE-NOT:    store
+;
+; SIMPLIFYCFG-LABEL: @_Z4funcv(
+; SIMPLIFYCFG-NOT:    unreachable
+;
+entry:
+  br label %delete.notnull
+
+delete.notnull:                                   ; preds = %entry
+  call void @_ZdlPv(i8* undef)
+  br label %delete.end
+
+delete.end:                                       ; preds = %delete.notnull
+  ret i32 1
+}
+
+; Function Attrs: nobuiltin nounwind
+declare dso_local void @_ZdlPv(i8*) local_unnamed_addr
+
+; Function Attrs: mustprogress norecurse nounwind uwtable
+define dso_local i32 @main() local_unnamed_addr {
+entry:
+  %call = call i32 @_Z4funcv()
+  ret i32 0
+}
+