diff --git a/src/link/MachO.zig b/src/link/MachO.zig
index 9cec01c437..dd185fcaec 100644
--- a/src/link/MachO.zig
+++ b/src/link/MachO.zig
@@ -192,7 +192,7 @@ pub fn createEmpty(
         null
     else
         try std.fmt.allocPrint(arena, "{s}.o", .{emit.sub_path});
-    const allow_shlib_undefined = options.allow_shlib_undefined orelse false;
+    const allow_shlib_undefined = options.allow_shlib_undefined orelse comp.config.any_sanitize_thread;
 
     const self = try arena.create(MachO);
     self.* = .{
@@ -411,6 +411,11 @@ pub fn flushModule(self: *MachO, arena: Allocator, prog_node: std.Progress.Node)
 
     if (module_obj_path) |path| try positionals.append(.{ .path = path });
 
+    // TSAN
+    if (comp.config.any_sanitize_thread) {
+        try positionals.append(.{ .path = comp.tsan_static_lib.?.full_object_path });
+    }
+
     for (positionals.items) |obj| {
         self.parsePositional(obj.path, obj.must_link) catch |err| switch (err) {
             error.MalformedObject,
@@ -825,6 +830,10 @@ fn dumpArgv(self: *MachO, comp: *Compilation) !void {
             try argv.append(p);
         }
 
+        if (comp.config.any_sanitize_thread) {
+            try argv.append(comp.tsan_static_lib.?.full_object_path);
+        }
+
         for (self.lib_dirs) |lib_dir| {
             const arg = try std.fmt.allocPrint(arena, "-L{s}", .{lib_dir});
             try argv.append(arg);