Julia_says etymology of the name is most definitely untrue. The name derives from bori[ti] (fight/battle) and slav (glory/fame). Boris has nothing to do with this name. In fact the name Boris is mistakenly believed to be Tatar but is also of Slavic origin and related to battle (bori[ti]).
It is a very beautiful name indeed. It sounds great, it looks marvelous written down. As I pointed out earlier it means "struggling for glory" or "fame in battle". The name originates from "Boris" (which has a few possible meanings, among which - "wolf", "tiger" or "short"). Its origin is Turko-Altayan ditto the other comment. To "Boris" is added the suffix "slav", which means "fame", glory" and is common for Slavic names (Svetoslav, Stanislav, Luboslav etc). The name is just another proof for the fusion of Pre-Bulgarians and Slavic tribes that formed the Bulgarian nationality - (8-9th century AD). "Boris" (Bulgarian) + "Slav" (Slavic) :-) The bearers of the name are usually called shortly "Boris" or "Borko".
The name means "struggling for glory". "Fame in battle" is another possible interpretation indeed. "Borislav" is derived from "Boris". Purely Bulgarian name.
It is Bulgarian as well, however many of the Slavic entries seem to confuse Bulgarian names with Russian. Many of the so-called Russian names are not used in Russia today, perhaps never were. Including Borislav.