diff --git a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
--- a/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
+++ b/llvm/lib/CodeGen/MIRCanonicalizerPass.cpp
@@ -104,6 +104,8 @@
                     "Rename Register Operands Canonically", false, false)
 
 static std::vector<MachineBasicBlock *> GetRPOList(MachineFunction &MF) {
+  if (MF.empty())
+    return {};
   ReversePostOrderTraversal<MachineBasicBlock *> RPOT(&*MF.begin());
   std::vector<MachineBasicBlock *> RPOList;
   for (auto MBB : RPOT) {
diff --git a/llvm/test/CodeGen/MIR/AArch64/empty-MF.mir b/llvm/test/CodeGen/MIR/AArch64/empty-MF.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/AArch64/empty-MF.mir
@@ -0,0 +1,8 @@
+# RUN: llc -mtriple aarch64-- -run-pass mir-canonicalizer %s -o %t \
+# RUN:   -verify-machineinstrs
+
+--- |
+  define void @foo() {
+    ret void
+  }
+...