diff --git a/lib/Target/ARM/README.txt b/lib/Target/ARM/README.txt
index 3e248a6c927..4223699b9d0 100644
--- a/lib/Target/ARM/README.txt
+++ b/lib/Target/ARM/README.txt
@@ -528,3 +528,5 @@ those operations and the ARMv6 scalar versions.
 
 //===---------------------------------------------------------------------===//
 
+ARM::MOVCCr is commutable (by flipping the condition). But we need to implement
+ARMInstrInfo::commuteInstruction() to support it.