diff --git a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
--- a/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp
@@ -2070,11 +2070,14 @@
       OrigPhiRef = Phi;
       if (Phi->getType()->isIntegerTy() && TTI &&
           TTI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
-        // This phi can be freely truncated to the narrowest phi type. Map the
-        // truncated expression to it so it will be reused for narrow types.
-        const SCEV *TruncExpr =
-          SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
-        ExprToIVMap[TruncExpr] = Phi;
+        const SCEV *PhiExpr = SE.getSCEV(Phi);
+        if (isa<SCEVAddRecExpr>(PhiExpr)) {
+          // This phi can be freely truncated to the narrowest phi type. Map the
+          // truncated expression to it so it will be reused for narrow types.
+          const SCEV *TruncExpr =
+            SE.getTruncateExpr(PhiExpr, Phis.back()->getType());
+          ExprToIVMap[TruncExpr] = Phi;
+        }
       }
       continue;
     }
diff --git a/llvm/test/Transforms/IndVarSimplify/AArch64/widen-loop-comp.ll b/llvm/test/Transforms/IndVarSimplify/AArch64/widen-loop-comp.ll
--- a/llvm/test/Transforms/IndVarSimplify/AArch64/widen-loop-comp.ll
+++ b/llvm/test/Transforms/IndVarSimplify/AArch64/widen-loop-comp.ll
@@ -1446,9 +1446,9 @@
 ; CHECK-NEXT:    store i16 0, i16* [[PTR:%.*]], align 4
 ; CHECK-NEXT:    br label [[LOOP:%.*]]
 ; CHECK:       loop:
-; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[IV_NEXT:%.*]], [[LOOP]] ], [ 0, [[ENTRY:%.*]] ]
-; CHECK-NEXT:    [[INDVARS:%.*]] = trunc i32 [[IV]] to i16
-; CHECK-NEXT:    [[VAL_INC:%.*]] = add i16 [[INDVARS]], 1
+; CHECK-NEXT:    [[VAL:%.*]] = phi i16 [ [[VAL_INC:%.*]], [[LOOP]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[IV_NEXT:%.*]], [[LOOP]] ], [ 0, [[ENTRY]] ]
+; CHECK-NEXT:    [[VAL_INC]] = add i16 [[VAL]], 1
 ; CHECK-NEXT:    store i16 [[VAL_INC]], i16* [[PTR]], align 4
 ; CHECK-NEXT:    [[IV_WIDE:%.*]] = zext i32 [[IV]] to i64
 ; CHECK-NEXT:    call void @foo(i64 [[IV_WIDE]])