diff --git a/llvm/utils/gn/secondary/lld/MachO/BUILD.gn b/llvm/utils/gn/secondary/lld/MachO/BUILD.gn
index 22fee55efe6d..185ce24c7025 100644
--- a/llvm/utils/gn/secondary/lld/MachO/BUILD.gn
+++ b/llvm/utils/gn/secondary/lld/MachO/BUILD.gn
@@ -22,6 +22,7 @@ static_library("MachO2") {
     "//libunwind/include",
   ]
   sources = [
+    "Arch/ARM.cpp",
     "Arch/ARM64.cpp",
     "Arch/ARM64Common.cpp",
     "Arch/ARM64_32.cpp",