Here's the output of `docker -h` from a more recent master-based version than 0.9.1:
```console
$ docker -h
Usage of docker:
  --api-enable-cors=false: Enable CORS headers in the remote API
  -b, --bridge="": Attach containers to a pre-existing network bridge; use 'none' to disable container networking
  --bip="": Use this CIDR notation address for the network bridge's IP, not compatible with -b
  -d, --daemon=false: Enable daemon mode
  -D, --debug=false: Enable debug mode
  --dns=[]: Force docker to use specific DNS servers
  --dns-search=[]: Force Docker to use specific DNS search domains
  -e, --exec-driver="native": Force the docker runtime to use a specific exec driver
  -G, --group="docker": Group to assign the unix socket specified by -H when running in daemon mode; use '' (the empty string) to disable setting of a group
  -g, --graph="/var/lib/docker": Path to use as the root of the docker runtime
  -H, --host=[]: tcp://host:port, unix://path/to/socket, fd://* or fd://socketfd to use in daemon mode. Multiple sockets can be specified
  --icc=true: Enable inter-container communication
  --ip="0.0.0.0": Default IP address to use when binding container ports
  --ip-forward=true: Enable net.ipv4.ip_forward
  --iptables=true: Enable Docker's addition of iptables rules
  --mtu=0: Set the containers network MTU; if no value is provided: default to the default route MTU or 1500 if no default route is available
  -p, --pidfile="/var/run/docker.pid": Path to use for daemon PID file
  -r, --restart=true: Restart previously running containers
  -s, --storage-driver="": Force the docker runtime to use a specific storage driver
  --tls=false: Use TLS; implied by tls-verify flags
  --tlscacert="/home/tianon/.docker/ca.pem": Trust only remotes providing a certificate signed by the CA given here
  --tlscert="/home/tianon/.docker/cert.pem": Path to TLS certificate file
  --tlskey="/home/tianon/.docker/key.pem": Path to TLS key file
  --tlsverify=false: Use TLS and verify the remote (daemon: verify client, client: verify daemon)
  -v, --version=false: Print version information and quit
```