diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -815,6 +815,16 @@
 
   if (auto e = buffer->commit())
     error("failed to write to the output file: " + toString(std::move(e)));
+
+  // TODO(gkm): replace with code to populate the synthetic section
+  // LC_CODE_SIGNATURE. For sake of expediency during arm64 bring-up,
+  // just do it by fork+exec.
+  std::string codesign("/usr/bin/codesign");
+  if (!errorCount() && config->outputType == MH_EXECUTE &&
+      (config->arch == AK_arm64 || config->arch == AK_arm64e) &&
+      config->platform.kind == PlatformKind::macOS &&
+      sys::fs::can_execute(codesign.c_str()))
+    std::system((codesign + " -s - " + config->outputFile).str().c_str());
 }
 
 void macho::writeResult() { Writer().run(); }