./configure -opensource -optimized-qmake -c++11

This results in an error saying that my compiler (clang) doesn't support C++11. Passing the -v (verbose) option to configure shows the following (trimming the other parts):

C++11 auto-detection... ()
clang++ -c -pipe -mmacosx-version-min=10.6 -O2 -std=c++11 -Wall -W -fPIE -I../../../mkspecs/macx-clang -I. -o c++11.o c++11.cpp
c++11.cpp:50:4: error: "C++11 with clang requires libc++ runtime"

error "C++11 with clang requires libc++ runtime"

^
1 error generated.
make: *** [c++11.o] Error 1
C++11 disabled.
C++11 support cannot be enabled due to functionality tests!

clang does indeed support C++11, but there are two problems with this functionality test. First, -stdlib=libc++ must be explicitly stated to link to the right runtime. Second, -mmacosx-version-min should be 10.7, because that's the minimum target version for applications using C++11 (at least as far as the OS X SDK is concerned). As far as I can tell, I can't pass these options through configure, which to me suggests that the test is wrong.

Is there a problem in the configure/feature detection? Or is there a problem in the way in which I'm invoking configure?

If you need it, my setup is:

clang --version
Apple LLVM version 4.2 (clang-425.0.27) (based on LLVM 3.2svn)
Target: x86_64-apple-darwin12.3.0
Thread model: posix

OS X 10.8.3

Xcode 4.6.1