diff --git a/lib/Target/ARM/README-Thumb.txt b/lib/Target/ARM/README-Thumb.txt
index 4da1876637c..63bc004552c 100644
--- a/lib/Target/ARM/README-Thumb.txt
+++ b/lib/Target/ARM/README-Thumb.txt
@@ -167,3 +167,8 @@ LPC0:
 	cpy r3, r6
 	cpy lr, pc
 	bx r5
+
+//===---------------------------------------------------------------------===//
+
+Make register allocator / spiller smarter so we can re-materialize "mov r, imm",
+etc. Almost all Thumb instructions clobber condition code.