diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -951,15 +951,16 @@
   }
 
   // trunc (ctlz_i32(zext(A), B) --> add(ctlz_i16(A, B), C)
-  if (match(Src, m_OneUse(m_Intrinsic<Intrinsic::ctlz>(
-                     m_OneUse(m_ZExt(m_Value(A))), m_Value(B))))) {
-    Value *WidthDiff =
-        ConstantInt::get(A->getType(), Src->getType()->getScalarSizeInBits() -
-                                           A->getType()->getScalarSizeInBits());
-
-    Value *NarrowCtlz =
-        Builder.CreateIntrinsic(Intrinsic::ctlz, {Trunc.getType()}, {A, B});
-    return BinaryOperator::CreateAdd(NarrowCtlz, WidthDiff);
+  if (match(Src, m_OneUse(m_Intrinsic<Intrinsic::ctlz>(m_ZExt(m_Value(A)),
+                                                       m_Value(B))))) {
+    unsigned AWidth = A->getType()->getScalarSizeInBits();
+
+    if (AWidth == DestWidth && AWidth > 5) {
+      Value *WidthDiff = ConstantInt::get(A->getType(), SrcWidth - AWidth);
+      Value *NarrowCtlz =
+          Builder.CreateIntrinsic(Intrinsic::ctlz, {Trunc.getType()}, {A, B});
+      return BinaryOperator::CreateAdd(NarrowCtlz, WidthDiff);
+    }
   }
   return nullptr;
 }
diff --git a/llvm/test/Transforms/InstCombine/zext-ctlz-trunc-to-ctlz-add.ll b/llvm/test/Transforms/InstCombine/zext-ctlz-trunc-to-ctlz-add.ll
--- a/llvm/test/Transforms/InstCombine/zext-ctlz-trunc-to-ctlz-add.ll
+++ b/llvm/test/Transforms/InstCombine/zext-ctlz-trunc-to-ctlz-add.ll
@@ -71,8 +71,8 @@
 define <vscale x 2 x i16> @trunc_ctlz_zext_nxv2i16_nxv2i63_multiple_uses(<vscale x 2 x i16> %x) {
 ; CHECK-LABEL: @trunc_ctlz_zext_nxv2i16_nxv2i63_multiple_uses(
 ; CHECK-NEXT:    [[Z:%.*]] = zext <vscale x 2 x i16> [[X:%.*]] to <vscale x 2 x i63>
-; CHECK-NEXT:    [[P:%.*]] = call <vscale x 2 x i63> @llvm.ctlz.nxv2i63(<vscale x 2 x i63> [[Z]], i1 true)
-; CHECK-NEXT:    [[ZZ:%.*]] = trunc <vscale x 2 x i63> [[P]] to <vscale x 2 x i16>
+; CHECK-NEXT:    [[TMP1:%.*]] = call <vscale x 2 x i16> @llvm.ctlz.nxv2i16(<vscale x 2 x i16> [[X]], i1 true)
+; CHECK-NEXT:    [[ZZ:%.*]] = add nuw nsw <vscale x 2 x i16> [[TMP1]], shufflevector (<vscale x 2 x i16> insertelement (<vscale x 2 x i16> undef, i16 47, i32 0), <vscale x 2 x i16> undef, <vscale x 2 x i32> zeroinitializer)
 ; CHECK-NEXT:    call void @use1(<vscale x 2 x i63> [[Z]])
 ; CHECK-NEXT:    ret <vscale x 2 x i16> [[ZZ]]
 ;
@@ -83,3 +83,33 @@
   ret <vscale x 2 x i16> %zz
 }
 
+; Negative case where types of x and zz don't match
+
+define i16 @trunc_ctlz_zext_i10_i32(i10 %x) {
+; CHECK-LABEL: @trunc_ctlz_zext_i10_i32(
+; CHECK-NEXT:    [[Z:%.*]] = zext i10 [[X:%.*]] to i32
+; CHECK-NEXT:    [[P:%.*]] = call i32 @llvm.ctlz.i32(i32 [[Z]], i1 false), !range [[RNG1:![0-9]+]]
+; CHECK-NEXT:    [[ZZ:%.*]] = trunc i32 [[P]] to i16
+; CHECK-NEXT:    ret i16 [[ZZ]]
+;
+  %z = zext i10 %x to i32
+  %p = call i32 @llvm.ctlz.i32(i32 %z, i1 false)
+  %zz = trunc i32 %p to i16
+  ret i16 %zz
+}
+
+; Negative case where size of x is less than 6
+
+define i5 @trunc_ctlz_zext_i5_i32(i5 %x) {
+; CHECK-LABEL: @trunc_ctlz_zext_i5_i32(
+; CHECK-NEXT:    [[Z:%.*]] = zext i5 [[X:%.*]] to i32
+; CHECK-NEXT:    [[P:%.*]] = call i32 @llvm.ctlz.i32(i32 [[Z]], i1 false), !range [[RNG2:![0-9]+]]
+; CHECK-NEXT:    [[ZZ:%.*]] = trunc i32 [[P]] to i5
+; CHECK-NEXT:    ret i5 [[ZZ]]
+;
+  %z = zext i5 %x to i32
+  %p = call i32 @llvm.ctlz.i32(i32 %z, i1 false)
+  %zz = trunc i32 %p to i5
+  ret i5 %zz
+}
+