diff --git a/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp b/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
--- a/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
+++ b/llvm/lib/Target/MSP430/MSP430ISelLowering.cpp
@@ -571,6 +571,7 @@
   switch (CallConv) {
   default:
     report_fatal_error("Unsupported calling convention");
+  case CallingConv::MSP430_BUILTIN:
   case CallingConv::C:
   case CallingConv::Fast:
     return LowerCCCArguments(Chain, CallConv, isVarArg, Ins, dl, DAG, InVals);
diff --git a/llvm/test/CodeGen/MSP430/cc_args.ll b/llvm/test/CodeGen/MSP430/cc_args.ll
--- a/llvm/test/CodeGen/MSP430/cc_args.ll
+++ b/llvm/test/CodeGen/MSP430/cc_args.ll
@@ -215,4 +215,24 @@
   ret i64 %3
 }
 
+define cc94 i64 @helper_i64(i64 %a, i64 %b) {
+; CHECK-LABEL: helper_i64:
+; CHECK: mov	r15, &g_i64_2+6
+; CHECK-NEXT: mov	r14, &g_i64_2+4
+; CHECK-NEXT: mov	r13, &g_i64_2+2
+; CHECK-NEXT: mov	r12, &g_i64_2
+; CHECK-NEXT: mov	r11, &g_i64+6
+; CHECK-NEXT: mov	r10, &g_i64+4
+; CHECK-NEXT: mov	r9, &g_i64+2
+; CHECK-NEXT: mov	r8, &g_i64
+; CHECK-NEXT: mov	#30600, r12
+; CHECK-NEXT: mov	#21862, r13
+; CHECK-NEXT: mov	#13124, r14
+; CHECK-NEXT: mov	#4386, r15
+; CHECK-NEXT: ret
+  store i64 %a, i64* @g_i64, align 2
+  store i64 %b, i64* @g_i64_2, align 2
+  ret i64 1234605616436508552
+}
+
 attributes #0 = { nounwind "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }