diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index c46468f..a258d34 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -929,6 +929,7 @@
     break;
   case Builtin::BI__va_start: {
     switch (Context.getTargetInfo().getTriple().getArch()) {
+    case llvm::Triple::aarch64:
     case llvm::Triple::arm:
     case llvm::Triple::thumb:
       if (SemaBuiltinVAStartARMMicrosoft(TheCall))