In English, a person who loves books is known as a bibliophile. The only translation that I can find for this word in Italian is bibliofilo which is deeply disappointing, given that the language is so adaptive. Is there a word which is not an Italian conversion of a word stolen from French by English for this sort of person?
Not really sure why you are disappointed... but that is the word commonly used and I am not aware of any common synonym, unless you use a periphrasis and say collezionista di libri.
On the issue of whether it is a French loan-word I am not completely sure, but then again, the French word comes from Greek as well (βιβλίον "book" and ϕιλία "love").
EDIT: following from egreg's comment, I looked for instances of bibliophile in other languages.
Google Books lists a Bulletin du bibliophile, du bibliothécaire et de la Société des amis de la Bibliothèque nationale et des grandes bibliothèques de France dated 1833
As noted by egreg, the OED has a 1824 quote for bibliophile
This suggests the word pre-dates this time, at least in France (since a Society of Bibliophiles apparently existed in Paris).
Data from Google Ngram shows pretty much the same trend (note that those peaks in the 1600 are spurious. Essentially they come from modern reprints of old books, and the word bibliophile is not actually in the body of the old book) If anything I would say that the word started getting used pretty much at the same time in Italy and France, and was later adopted in English.
EDIT 2: I would also add another possibility, which is bibliomane, corresponding to the English bibliomaniac. This, however, has a slightly negative connotation, which is well explained by the Enciclopedia Treccani at bibliomania
That page refers to a French book, called De la bibliomanie, dated 1761. Furthermore, they explain how the phenomenon probably predates the word!
It appears that bibliofilo is the only word equivalent to the English bibliophile. If you must really use a synonym, you can say topo di biblioteca, which has the same meaning but belongs to a lower registry.