--help not supported?

[oxalica]

I want to get a quick help of CLI parameters of criterion benches. Thus I tried:
cargo bench --bench=mybench -- --help
But it gives:

> cargo bench --bench=mybench -- --help
    Finished bench [optimized + debuginfo] target(s) in 0.03s
     Running benches/mybench.rs (/home/oxa/.cache/testt-target/release/deps/mybench-c6d0eae38261b75f)
Gnuplot not found, using plotters backend
error: unexpected argument found
error: bench failed, to rerun pass `--bench mybench`

Caused by:
  process didn't exit successfully: `/home/oxa/.cache/testt-target/release/deps/mybench-c6d0eae38261b75f --help --bench` (exit status: 2)

Even if I directly run the executable file, without cargo. It shows the same error.

> /home/oxa/.cache/testt-target/release/deps/mybench-c6d0eae38261b75f --help
Gnuplot not found, using plotters backend
error: unexpected argument found

I already have harness = false and other flags like --baseline all work. Just that --help is not recognized. Is this intentional or something going wrong?

I'm using criterion v0.5.1