diff --git a/lib/Target/X86/X86Instr64bit.td b/lib/Target/X86/X86Instr64bit.td
index c4b25fca2fc..1dd7e07964e 100644
--- a/lib/Target/X86/X86Instr64bit.td
+++ b/lib/Target/X86/X86Instr64bit.td
@@ -245,6 +245,18 @@ let Defs = [RCX,RDI], Uses = [RAX,RCX,RDI] in
 def REP_STOSQ : RI<0xAB, RawFrm, (outs), (ins), "{rep;stosq|rep stosq}",
                    [(X86rep_stos i64)]>, REP;
 
+// Fast system-call instructions
+def SYSCALL  : I<0x05, RawFrm,
+                 (outs), (ins), "syscall", []>, TB;
+def SYSENTER  : I<0x34, RawFrm,
+                  (outs), (ins), "sysenter", []>, TB;
+def SYSEXIT : I<0x35, RawFrm,
+                (outs), (ins), "sysexit", []>, TB;
+def SYSEXIT64 : RI<0x35, RawFrm,
+                   (outs), (ins), "sysexit", []>, TB;
+def SYSRET : I<0x07, RawFrm,
+               (outs), (ins), "sysret", []>, TB;
+
 //===----------------------------------------------------------------------===//
 //  Move Instructions...
 //