diff --git a/cmd/tailscale/cli/cli.go b/cmd/tailscale/cli/cli.go
index f8d5e0880..623b4a3bd 100644
--- a/cmd/tailscale/cli/cli.go
+++ b/cmd/tailscale/cli/cli.go
@@ -68,6 +68,11 @@ change in the future.
 		Exec:    func(context.Context, []string) error { return flag.ErrHelp },
 	}
 
+	// Don't advertise the debug command, but it exists.
+	if strSliceContains(args, "debug") {
+		rootCmd.Subcommands = append(rootCmd.Subcommands, debugCmd)
+	}
+
 	if err := rootCmd.Parse(args); err != nil {
 		return err
 	}
@@ -129,3 +134,12 @@ func pump(ctx context.Context, bc *ipn.BackendClient, conn net.Conn) {
 		bc.GotNotifyMsg(msg)
 	}
 }
+
+func strSliceContains(ss []string, s string) bool {
+	for _, v := range ss {
+		if v == s {
+			return true
+		}
+	}
+	return false
+}
diff --git a/cmd/tailscale/cli/debug.go b/cmd/tailscale/cli/debug.go
new file mode 100644
index 000000000..50e9b9c23
--- /dev/null
+++ b/cmd/tailscale/cli/debug.go
@@ -0,0 +1,43 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cli
+
+import (
+	"context"
+	"errors"
+	"flag"
+	"os"
+
+	"github.com/peterbourgon/ff/v2/ffcli"
+	"tailscale.com/client/tailscale"
+)
+
+var debugCmd = &ffcli.Command{
+	Name: "debug",
+	Exec: runDebug,
+	FlagSet: (func() *flag.FlagSet {
+		fs := flag.NewFlagSet("debug", flag.ExitOnError)
+		fs.BoolVar(&debugArgs.goroutines, "daemon-goroutines", false, "If true, dump the tailscaled daemon's goroutines")
+		return fs
+	})(),
+}
+
+var debugArgs struct {
+	goroutines bool
+}
+
+func runDebug(ctx context.Context, args []string) error {
+	if len(args) > 0 {
+		return errors.New("unknown arguments")
+	}
+	if debugArgs.goroutines {
+		goroutines, err := tailscale.Goroutines(ctx)
+		if err != nil {
+			return err
+		}
+		os.Stdout.Write(goroutines)
+	}
+	return nil
+}