proxy_pass to upstream with client certificate

[mangler]

Is it possible to configure nginx to send a client certificate to
upstream?

I'd like the flow to be:
HTTP to nginx which proxies to HTTPS://xyz/ that uses a client
certificate.

I don't want the end client to use any certificate what so ever
(preferably).

Regards,
Magnus Jäderberg

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,221563,221563#msg-221563