diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -2655,10 +2655,15 @@
 
 void PPCInstrInfo::fixupIsDeadOrKill(MachineInstr &StartMI, MachineInstr &EndMI,
                                      unsigned RegNo) const {
-
-  // Instructions between [StartMI, EndMI] should be in same basic block.
-  assert((StartMI.getParent() == EndMI.getParent()) &&
-         "Instructions are not in same basic block");
+  // Conservatively clear kill flag for the register if the instructions are in
+  // different basic blocks, because the kill flag may no longer be right. There
+  // is no need to bother with dead flags since defs with no uses will be
+  // handled by DCE.
+  MachineRegisterInfo &MRI = StartMI.getParent()->getParent()->getRegInfo();
+  if ((StartMI.getParent() != EndMI.getParent())) {
+    MRI.clearKillFlags(RegNo);
+    return;
+  }
 
   bool IsKillSet = false;
 
diff --git a/llvm/test/CodeGen/PowerPC/fixup-kill-dead-flag-crash.mir b/llvm/test/CodeGen/PowerPC/fixup-kill-dead-flag-crash.mir
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/fixup-kill-dead-flag-crash.mir
@@ -0,0 +1,21 @@
+# RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -verify-machineinstrs -start-before ppc-mi-peepholes \
+# RUN:   -stop-after ppc-mi-peepholes %s -o - | FileCheck %s
+
+---
+name: test
+#CHECK : name : test
+tracksRegLiveness: true
+body: |
+  bb.0.entry:
+    liveins: $x3
+    %0:g8rc = COPY $x3
+    %1:gprc = COPY %0.sub_32:g8rc
+    %2:g8rc = LI8 63
+
+  bb.1:
+    %3:gprc = COPY %2.sub_32:g8rc
+    ; CHECK: %4:gprc = LI 0
+    %4:gprc = XORI killed %3:gprc, 63
+    STW killed %4:gprc, %4:gprc, 100
+    BLR8 implicit $lr8, implicit $rm
+...