/usr/src/ is in llvm-2.9-source 2.9+dfsg-3ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/src/llvm-2.9/
/usr/src/llvm-2.9/llvm-2.9.tar.xz
/usr/src/llvm-2.9/patches/
/usr/src/llvm-2.9/patches/0003-Debian-version-info-and-bugreport.patch
/usr/src/llvm-2.9/patches/0002-Fix-llvm-config-script.patch
/usr/src/llvm-2.9/patches/0023-link-libopagent.patch
/usr/src/llvm-2.9/patches/0032-x86-fast-isel-fs-load.patch
/usr/src/llvm-2.9/patches/0005-Disable-llvm-stub.patch
/usr/src/llvm-2.9/patches/0001-Update-configure-script-for-kfreebsd-gnu-and-hurd.patch
/usr/src/llvm-2.9/patches/0033-renamed-manpages.patch
/usr/src/llvm-2.9/patches/0031-mips-version-script.patch
/usr/src/llvm-2.9/patches/0021-shared-lib-debian.patch
/usr/src/llvm-2.9/patches/0011-Hurd-fixes.patch
/usr/src/llvm-2.9/patches/disabled/
/usr/src/llvm-2.9/patches/disabled/0011-gcc-4.4-thumb.patch
/usr/src/llvm-2.9/patches/0012-RUNTESTFLAGS.patch
/usr/src/llvm-2.9/patches/0008-path-eraseFromDisk.patch
/usr/src/llvm-2.9/patches/0009-Fix-doclinks.patch