diff --git a/lib/AsmParser/Lexer.l b/lib/AsmParser/Lexer.l
index f930609..dc94cca 100644
--- a/lib/AsmParser/Lexer.l
+++ b/lib/AsmParser/Lexer.l
@@ -218,6 +218,7 @@
 
 cc              { return CC_TOK; }
 ccc             { return CCC_TOK; }
+csretcc         { return CSRETCC_TOK; }
 fastcc          { return FASTCC_TOK; }
 coldcc          { return COLDCC_TOK; }
 
diff --git a/lib/AsmParser/llvmAsmParser.y b/lib/AsmParser/llvmAsmParser.y
index cf74600..927b120 100644
--- a/lib/AsmParser/llvmAsmParser.y
+++ b/lib/AsmParser/llvmAsmParser.y
@@ -981,7 +981,7 @@
 %token TO DOTDOTDOT NULL_TOK UNDEF CONST INTERNAL LINKONCE WEAK  APPENDING
 %token OPAQUE NOT EXTERNAL TARGET TRIPLE ENDIAN POINTERSIZE LITTLE BIG ALIGN
 %token DEPLIBS CALL TAIL ASM_TOK MODULE SIDEEFFECT
-%token CC_TOK CCC_TOK FASTCC_TOK COLDCC_TOK
+%token CC_TOK CCC_TOK CSRETCC_TOK FASTCC_TOK COLDCC_TOK
 %type <UIntVal> OptCallingConv
 
 // Basic Block Terminating Operators
@@ -1054,6 +1054,7 @@
 
 OptCallingConv : /*empty*/      { $$ = CallingConv::C; } |
                  CCC_TOK        { $$ = CallingConv::C; } |
+                 CSRETCC_TOK    { $$ = CallingConv::CSRet; } |
                  FASTCC_TOK     { $$ = CallingConv::Fast; } |
                  COLDCC_TOK     { $$ = CallingConv::Cold; } |
                  CC_TOK EUINT64VAL {