The OED tells us that “yore” is archaic and I note that Tolkien only used it poetically in the work.

• 01.074 The dwarves of yore made mighty spells,
• 10.035 To songs of yore re-sung.
• 15.038 The dwarves of yore made mighty spells,

“yore, adv. (and adj.).” OED Online. Oxford University Press, March 2015. Web. 19 May 2015.