Index: i386/i386.md
===================================================================
--- i386/i386.md	(revision 186558)
+++ i386/i386.md	(working copy)
@@ -58,6 +58,7 @@
 ;; X -- don't print any sort of PIC '@' suffix for a symbol.
 ;; & -- print some in-use local-dynamic symbol name.
 ;; H -- print a memory address offset by 8; used for sse high-parts
+;; K -- print HLE lock prefix
 ;; Y -- print condition for XOP pcom* instruction.
 ;; + -- print a branch hint as 'cs' or 'ds' prefix
 ;; ; -- print a semicolon (after prefixes due to bug in older gas).
Index: i386/sync.md
===================================================================
--- i386/sync.md	(revision 186558)
+++ i386/sync.md	(working copy)
@@ -455,7 +455,7 @@
 		  (match_operand:SWI 2 "nonmemory_operand" "0")))
    (clobber (reg:CC FLAGS_REG))]
   "TARGET_XADD"
-  "lock{%;} xadd{<imodesuffix>}\t{%0, %1|%1, %0}")
+  "lock{%;} %K3xadd{<imodesuffix>}\t{%0, %1|%1, %0}")
 
 ;; This peephole2 and following insn optimize
 ;; __sync_fetch_and_add (x, -N) == N into just lock {add,sub,inc,dec}