Index: include/llvm/CodeGen/MIRYamlMapping.h
===================================================================
--- include/llvm/CodeGen/MIRYamlMapping.h
+++ include/llvm/CodeGen/MIRYamlMapping.h
@@ -511,7 +511,7 @@
     YamlIO.mapOptional("regBankSelected", MF.RegBankSelected, false);
     YamlIO.mapOptional("selected", MF.Selected, false);
     YamlIO.mapOptional("failedISel", MF.FailedISel, false);
-    YamlIO.mapOptional("tracksRegLiveness", MF.TracksRegLiveness, false);
+    YamlIO.mapOptional("tracksRegLiveness", MF.TracksRegLiveness, true);
     YamlIO.mapOptional("registers", MF.VirtualRegisters,
                        std::vector<VirtualRegisterDefinition>());
     YamlIO.mapOptional("liveins", MF.LiveIns,
Index: test/CodeGen/MIR/X86/force-liveness-track.mir
===================================================================
--- /dev/null
+++ test/CodeGen/MIR/X86/force-liveness-track.mir
@@ -0,0 +1,13 @@
+# RUN: llc -o - %s -mtriple=x86_64 | FileCheck %s
+---
+# CHECK: xorl  %eax, %eax
+# CHECK: movl  %eax, (%rcx)
+# CHECK: retq
+name: func0
+body: |
+  bb.0:
+    %0 : gr32 = MOV32r0 implicit-def $eflags
+    dead %1 : gr32 = COPY %0
+    MOV32mr undef $rcx, 1, _, 0, _, killed %0 :: (volatile store 4)
+    RETQ undef $eax
+...