diff --git a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
--- a/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
+++ b/llvm/lib/Transforms/IPO/FunctionSpecialization.cpp
@@ -303,10 +303,14 @@
         isConstant(IV) ? Solver.getConstant(IV) : UndefValue::get(V->getType());
     V->replaceAllUsesWith(Const);
 
-    for (auto *U : Const->users())
-      if (auto *I = dyn_cast<Instruction>(U))
+    // Using replaceUsesWithIf is probably the easiest way to do this without
+    // duplicating code.
+    V->replaceUsesWithIf(Const, [&](auto &U) {
+      if (auto *I = dyn_cast<Instruction>(U.getUser()))
         if (Solver.isBlockExecutable(I->getParent()))
           Solver.visit(I);
+      return true;
+    });
 
     // Remove the instruction from Block and Solver.
     if (auto *I = dyn_cast<Instruction>(V)) {