LLVM check-all with clang

I guess the problem is easy-solvable but I just can't figure out how.

I have built llvm + clang (release 38) using clang-3.5 as a compiler. Now I want to check-all, and here the trouble comes: a lot of tests crash with reports like bellow:

*** Do not use 'clang' in tests, use '%clang'. ***-cc1 -internal-isystem ../llvm/build/bin/../lib/clang/3.8.0/include -nostdsysteminc -fms-compatibility -fms-extensions -fsyntax-only -verify -std=c++11 .../llvm/tools/clang/test/SemaCXX/attr-selectany.cpp

Exit Code: 127

Googling this doesn't help a lot - at least, I couldn't find anything useful.

I can't understand, what does it mean - use %clang in tests instead of clang?