Re: (cross post from bug-make) A complete example of quoting an arbitrary value as a word in a shell script

Just Base64-encode the value as, say, the make variable B64VAL and do

 eval "$$(base64dec $(B64VAL))"

in the recipe or in a $(shell ...).

If that isn't palatable, invent some other encoding that is more readable.

URL encoding: percent hex notation for control and special characters. 

Quoted printable from MIME is another possibility.

You just have a dependency on the decoding tool. 

Or make up something decodable by an awk or sed one liner. Awk has environment access, and gmake can export.