diff --git a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
index 726d94b27a7f2..c7b941319f8b9 100644
--- a/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
+++ b/llvm/lib/Transforms/Instrumentation/ControlHeightReduction.cpp
@@ -1992,8 +1992,8 @@ void CHR::addToMergedCondition(bool IsTrueBiased, Value *Cond,
 
   // Use logical and to avoid propagating poison from later conditions.
   MergedCondition = IRB.CreateLogicalAnd(MergedCondition, Cond);
-  setExplicitlyUnknownBranchWeightsIfProfiled(
-      *cast<Instruction>(MergedCondition), DEBUG_TYPE);
+  if (auto *MergedInst = dyn_cast<Instruction>(MergedCondition))
+    setExplicitlyUnknownBranchWeightsIfProfiled(*MergedInst, DEBUG_TYPE, &F);
 }
 
 void CHR::transformScopes(SmallVectorImpl<CHRScope *> &CHRScopes) {
diff --git a/llvm/test/Transforms/PGOProfile/chr-unknown-profdata-crash.ll b/llvm/test/Transforms/PGOProfile/chr-unknown-profdata-crash.ll
new file mode 100644
index 0000000000000..220f442a6b681
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/chr-unknown-profdata-crash.ll
@@ -0,0 +1,33 @@
+; RUN: opt < %s -passes='require<profile-summary>,function(chr)' -force-chr -chr-merge-threshold=1 -disable-output
+
+; Regression test for a crash in CHR when setting unknown profdata on the
+; merged condition. IRBuilder::CreateLogicalAnd is implemented as a select and
+; can constant-fold to a non-Instruction value (e.g. `i1 true`). The buggy code
+; assumed it always produced an Instruction and did `cast<Instruction>(V)`,
+; which can segfault in release builds.
+define void @repro_crash() {
+entry:
+  br i1 true, label %then, label %exit, !prof !15
+
+then:
+  br label %exit
+
+exit:
+  ret void
+}
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"ProfileSummary", !1}
+!1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
+!2 = !{!"ProfileFormat", !"InstrProf"}
+!3 = !{!"TotalCount", i64 10000}
+!4 = !{!"MaxCount", i64 10}
+!5 = !{!"MaxInternalCount", i64 1}
+!6 = !{!"MaxFunctionCount", i64 1000}
+!7 = !{!"NumCounts", i64 1}
+!8 = !{!"NumFunctions", i64 1}
+!9 = !{!"DetailedSummary", !10}
+!10 = !{!11}
+!11 = !{i32 999999, i64 1, i32 1}
+
+!15 = !{!"branch_weights", i32 100, i32 1}