--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/CodeGen/AVR/select-mbb-placement-bug.ll	Fri Oct 27 17:07:41 2017 +0900
@@ -0,0 +1,35 @@
+; RUN: llc -mcpu=atmega328p < %s -march=avr | FileCheck %s
+
+; CHECK-LABEL: loopy
+define internal fastcc void @loopy() {
+
+; In this case, when we expand `Select8`/`Select16`, we should be
+; replacing the existing MBB instead of adding a new one.
+;
+; https://github.com/avr-rust/rust/issues/49
+
+; CHECK: LBB0_{{[0-9]+}}:
+; CHECK: LBB0_{{[0-9]+}}:
+; CHECK-NOT: LBB0_{{[0-9]+}}:
+start:
+  br label %bb7.preheader
+
+bb7.preheader:                                    ; preds = %bb10, %start
+  %i = phi i8 [ 0, %start ], [ %j, %bb10 ]
+  %j = phi i8 [ 1, %start ], [ %next, %bb10 ]
+  br label %bb10
+
+bb4:                                              ; preds = %bb10
+  ret void
+
+bb10:                                             ; preds = %bb7.preheader
+  tail call fastcc void @observe(i8 %i, i8 1)
+  %0 = icmp ult i8 %j, 20
+  %1 = zext i1 %0 to i8
+  %next = add i8 %j, %1
+  br i1 %0, label %bb7.preheader, label %bb4
+
+}
+
+declare void @observe(i8, i8);
+