Format: 

Lastname, Firstname, function(s). "Title of Song." Title of Album, contributor(s) function(s) by Firstname Lastname, Distributor or Record Label, Year. Database or Title of Website, URL. Accessed Day Month Year.

Lastname, Firstname, function(s). "Title of Song." Title of Album, contributor(s) function(s) by Firstname Lastname, Distributor or Record Label, Year.

Examples: 

Anderson-Lopez, Kristen, and Robert Lopez. "Do You Want To Build A Snowman?" Performance by Kristen Bell, Agatha Lee Monn, and Katie Lopez, Frozen: Original Motion Picture Soundtrack, Walt Disney Records, 2013.

In-text: (Anderson-Lopez and Lopez 00:01:15)

Menzel, Idina, performer. "Let It Go." Frozen: Original Motion Picture Soundtrack, written by Kristen Anderson-Lopez and Robert Lopez, Walt Disney Records, 2013. Amazon Music, https://music.amazon.com/albums/B00GLP47UM/B00GLP4DMO. Accessed 12 Dec. 2017.

In-text: (Menzel 00:15:14-37)

Williams, John, composer. Star Wars, Episode IV, "A New Hope" (Original Motion Picture Soundtrack). Performed by London Symphony Orchestra, Sony Classical Records, 2004, disc 2. Naxos Music Library, rit-naxosmusiclibrary-com.ezproxy.rit.edu/catalogue/item.asp?cid=884977716580. Accessed 12 Dec. 2017.

In-text: (Williams Track 4)

Notes: 

If you are emphasizing the contributions of a specific individual, begin the citation with that person's name (as above); otherwise, you may begin with the song or album title (MLA 24). You can also include any contributors you deem necessary such as performer(s) or songwriter(s). Contributors should appear between the title of the album and the record label and must be preceded by an appropriate function (MLA 37). Where you usually cite the publisher, include the name of the company responsible for the overall production of the song or album, typically the record label (MLA 41). For in-text citations, you can use a time-range instead of a page number as demonstrated above (MLA 57); you may also use a track number if your Works Cited entry is for the entire album (MLA 123). If you are not citing a specific individual, use the first word or noun phrase (first noun along with any preceding adjectives) of the title for the in-text citation (MLA 56).

Source:
MLA - p. 28