This is a chiffon top and skirt by Yves Saint Laurent from 1977. It's made of a sheer periwinkle chiffon with a multi sized polka dot pattern. The top includes two arm holes and features a tier that drapes off the shoulder and over the bust, with strips of fabric draped off the shoulder that can be tied into a bow or left loose. The prairie style skirt has multiple chiffon layers, an asymmetrical hem, and and elastic waist with a front tie as well.
Yves Saint Laurent Chiffon Top and Skirt from 1977 LU58332440473