diff --git a/llvm/tools/llvm-exegesis/lib/Assembler.cpp b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
--- a/llvm/tools/llvm-exegesis/lib/Assembler.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
@@ -21,6 +21,8 @@
 #include "llvm/CodeGen/TargetPassConfig.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/Support/Alignment.h"
@@ -84,6 +86,8 @@
   // Making sure we can create a MachineFunction out of this Function even if it
   // contains no IR.
   F->setIsMaterializable(true);
+  BasicBlock *BB = BasicBlock::Create(Module->getContext(), "", F);
+  new UnreachableInst(Module->getContext(), BB);
   return MMI->getOrCreateMachineFunction(*F);
 }