I would think it should be "... as THEY will do you harm."

„as“ ist hier, glaube ich, keine Konjunktion, sondern Vergleichspartikel (einer etwas literarischen Fügung).

Vgl. http://tatoeba.org/jpn/sentences/show/29199.

OK, thanks, Tommy and Lisa - This is not very familiar to me. I'll remove the NNC tags.

Die könntest Du ruhig lassen. Vielleicht versieht dann ein Muttersprachler die Sätze mit OK-Etiketten.

zvzuibqx, could you revert this sentence? The sentence was correct, even if it was old-fashioned. One of the rules here is not to change anything that is not wrong. Now it doesn't match the Japanese and the Russian (and probably also other) translations anymore.

Tommy_san and Pfirsichbaeumchen are correct. Both English sentences are equivalent:
You must not read such books as will do you harm.
You shouldn't read books that are harmful to you.

ACs (English): How about putting an OK tag with this sentence?

How about adopting the sentence? Or is it so awkward it has to stay a poor orphan forever, without a hearth and home? ☺

Dear Pfirsichbaeumchen, it's not at all awkward, merely high style or literary, and it's no longer a homeless poor orphan. Thanks for the suggestion.