clang-3.4 headers vs system libc++

[Jack Howarth]

Jeremy,
     I noticed that clang++ 3.4 compiles against the libc++ headers from that release but
actually links against the system libc++ rather than the one built from the libcxx
3.4 sources. The dissociation of the the compiled headers from the linked libc++ is
a bit worrying. While this shouldn't be as much of an issue for Mavericks's libc++
(current version 120.0.0), it is more so with Mountain Lion's libc++ (current version 65.1.0).
Has this issue been considered?
       Jack