When and how was the double-dash (–) introduced as an end of options delimiter in Unix/Linux?

I don’t think the shell/utilities in historical Unix nor in something as “recent” as 4.4BSD supported using a double-dash(or two consecutive hyphens) as an end of options delimiter. With FreeBSD, you can see for instance a note introduced in the rm manpages with the 2.2.1 release(1997). But this is just the documentation for one command.