“Liberal” used to mean that. According to the dictionary, WE are the liberals and the progressives too. Around the turn of the 19th century the term “liberal” was co-opted by socialists.
Yes, I'm aware that until perhaps the early 20th century, "liberal" meant essentially what "libertarian" means today.
You're correct that the word "liberal" was co-opted in the early 20th century to refer to the left. I'm not so sure how much that change in the semantics was from the left itself, or how much the change came about as a result of political commentators of the era.