diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4909,8 +4909,7 @@
   return nullptr;
 }
 
-static Instruction *foldICmpWithTrunc(ICmpInst &ICmp,
-                                      InstCombiner::BuilderTy &Builder) {
+Instruction *InstCombinerImpl::foldICmpWithTrunc(ICmpInst &ICmp) {
   ICmpInst::Predicate Pred = ICmp.getPredicate();
   Value *Op0 = ICmp.getOperand(0), *Op1 = ICmp.getOperand(1);
 
@@ -4948,6 +4947,25 @@
     return new ICmpInst(ICmpInst::ICMP_EQ, And, MaskC);
   }
 
+  if (auto *II = dyn_cast<IntrinsicInst>(X)) {
+    if (II->getIntrinsicID() == Intrinsic::cttz ||
+        II->getIntrinsicID() == Intrinsic::ctlz) {
+      unsigned MaxRet = SrcBits;
+      // If the "is_zero_poison" argument is set, then we know at least
+      // one bit is set in the input, so the result is always at least one
+      // less than the full bitwidth of that input.
+      if (match(II->getArgOperand(1), m_One()))
+        MaxRet--;
+
+      // Make sure the destination is wide enough to hold the largest output of
+      // the intrinsic.
+      if (llvm::Log2_32(MaxRet) + 1 <= Op0->getType()->getScalarSizeInBits())
+        if (Instruction *I =
+                foldICmpIntrinsicWithConstant(ICmp, II, C->zext(SrcBits)))
+          return I;
+    }
+  }
+
   return nullptr;
 }
 
@@ -5105,7 +5123,7 @@
       return new ICmpInst(ICmp.getPredicate(), Op0Src, NewOp1);
   }
 
-  if (Instruction *R = foldICmpWithTrunc(ICmp, Builder))
+  if (Instruction *R = foldICmpWithTrunc(ICmp))
     return R;
 
   return foldICmpWithZextOrSext(ICmp);
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -624,6 +624,7 @@
   Instruction *foldICmpEqIntrinsicWithConstant(ICmpInst &ICI, IntrinsicInst *II,
                                                const APInt &C);
   Instruction *foldICmpBitCast(ICmpInst &Cmp);
+  Instruction *foldICmpWithTrunc(ICmpInst &Cmp);
 
   // Helpers of visitSelectInst().
   Instruction *foldSelectOfBools(SelectInst &SI);
diff --git a/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll b/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
--- a/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
+++ b/llvm/test/Transforms/InstCombine/cmp-intrinsic.ll
@@ -543,9 +543,8 @@
 
 define i1 @trunc_cttz_ult_other_i33_i6(i33 %x) {
 ; CHECK-LABEL: @trunc_cttz_ult_other_i33_i6(
-; CHECK-NEXT:    [[TZ:%.*]] = tail call i33 @llvm.cttz.i33(i33 [[X:%.*]], i1 true), !range [[RNG1]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i33 [[TZ]] to i6
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i6 [[TRUNC]], 7
+; CHECK-NEXT:    [[TMP1:%.*]] = and i33 [[X:%.*]], 127
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i33 [[TMP1]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %tz = tail call i33 @llvm.cttz.i33(i33 %x, i1 true)
@@ -554,6 +553,8 @@
   ret i1 %cmp
 }
 
+; negative case: log2(33 - is_zero_poison ? 1 : 0) + 1 > 5
+
 define i1 @trunc_cttz_ult_other_i33_i5(i33 %x) {
 ; CHECK-LABEL: @trunc_cttz_ult_other_i33_i5(
 ; CHECK-NEXT:    [[TZ:%.*]] = tail call i33 @llvm.cttz.i33(i33 [[X:%.*]], i1 true), !range [[RNG1]]
@@ -569,9 +570,8 @@
 
 define i1 @trunc_cttz_true_ult_other_i32_i5(i32 %x) {
 ; CHECK-LABEL: @trunc_cttz_true_ult_other_i32_i5(
-; CHECK-NEXT:    [[TZ:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 true), !range [[RNG0]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[TZ]] to i5
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i5 [[TRUNC]], 7
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[X:%.*]], 127
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP1]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %tz = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
@@ -597,9 +597,8 @@
 
 define i1 @trunc_cttz_false_ult_other_i32_i6(i32 %x) {
 ; CHECK-LABEL: @trunc_cttz_false_ult_other_i32_i6(
-; CHECK-NEXT:    [[TZ:%.*]] = tail call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 false), !range [[RNG0]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[TZ]] to i6
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i6 [[TRUNC]], 7
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[X:%.*]], 127
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP1]], 0
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %tz = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
@@ -649,9 +648,7 @@
 
 define i1 @trunc_ctlz_ugt_other_i33_i6(i33 %x) {
 ; CHECK-LABEL: @trunc_ctlz_ugt_other_i33_i6(
-; CHECK-NEXT:    [[LZ:%.*]] = tail call i33 @llvm.ctlz.i33(i33 [[X:%.*]], i1 true), !range [[RNG1]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i33 [[LZ]] to i6
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i6 [[TRUNC]], 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i33 [[X:%.*]], 268435456
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %lz = tail call i33 @llvm.ctlz.i33(i33 %x, i1 true)
@@ -660,6 +657,8 @@
   ret i1 %cmp
 }
 
+; negative case: log2(33 - is_zero_poison ? 1 : 0) + 1 > 5
+
 define i1 @trunc_ctlz_ugt_other_i33_i5(i33 %x) {
 ; CHECK-LABEL: @trunc_ctlz_ugt_other_i33_i5(
 ; CHECK-NEXT:    [[LZ:%.*]] = tail call i33 @llvm.ctlz.i33(i33 [[X:%.*]], i1 true), !range [[RNG1]]
@@ -675,9 +674,7 @@
 
 define i1 @trunc_ctlz_true_ugt_other_i32_i5(i32 %x) {
 ; CHECK-LABEL: @trunc_ctlz_true_ugt_other_i32_i5(
-; CHECK-NEXT:    [[LZ:%.*]] = tail call i32 @llvm.ctlz.i32(i32 [[X:%.*]], i1 true), !range [[RNG0]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[LZ]] to i5
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i5 [[TRUNC]], 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[X:%.*]], 134217728
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %lz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
@@ -703,9 +700,7 @@
 
 define i1 @trunc_ctlz_false_ugt_other_i32_i6(i32 %x) {
 ; CHECK-LABEL: @trunc_ctlz_false_ugt_other_i32_i6(
-; CHECK-NEXT:    [[LZ:%.*]] = tail call i32 @llvm.ctlz.i32(i32 [[X:%.*]], i1 false), !range [[RNG0]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[LZ]] to i6
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ugt i6 [[TRUNC]], 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[X:%.*]], 134217728
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %lz = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
@@ -753,6 +748,8 @@
   ret i1 %cmp
 }
 
+; negative case: log2(33) + 1 > 4
+
 define i1 @trunc_negative_destbits_not_enough(i33 %x) {
 ; CHECK-LABEL: @trunc_negative_destbits_not_enough(
 ; CHECK-NEXT:    [[TZ:%.*]] = tail call i33 @llvm.cttz.i33(i33 [[X:%.*]], i1 false), !range [[RNG1]]