clang doesn't find stdc++ headers

When i try to run a simple c++ program like:
#include <iostream>
int main() {
std::cout << "HelloWorld" << std::endl;
return 0;

This is the verbose output:
$ clang++ test.cpp -o test -v
Ubuntu clang version 3.2-1~exp5ubuntu2 (tags/RELEASE_32/final) (based on LLVM 3.2)
Target: x86_64-pc-linux-gnu
Thread model: posix
 "/usr/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -disable-free -disable-llvm-verifier -main-file-name lambda.cpp -mrelocation-model static -mdisable-fp-elim -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -target-linker-version 2.23.1 -momit-leaf-frame-pointer -v -resource-dir /usr/bin/../lib/clang/3.2 -fmodule-cache-path /var/tmp/clang-module-cache -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib/clang/3.2/include -internal-isystem /usr/include/clang/3.2/include/ -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /usr/include -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /home/random/Projects/Tests -ferror-limit 19 -fmessage-length 80 -mstackrealign -fobjc-runtime=gcc -fcxx-exceptions -fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /tmp/lambda-3jYJtR.o -x c++ lambda.cpp
clang -cc1 version 3.2 based upon LLVM 3.2svn default target x86_64-pc-linux-gnu
ignoring nonexistent directory "/usr/include/c++/v1"
ignoring nonexistent directory "/usr/bin/../lib/clang/3.2/include"
ignoring duplicate directory "/usr/include/x86_64-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/include/clang/3.2/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
lambda.cpp:2:10: fatal error: 'iostream' file not found
#include <iostream>
         ^
1 error generated.

I'm currently running raring amd64.
Packages:
clang:
  Installed: 3.2-1~exp5ubuntu2
  Candidate: 3.2-1~exp5ubuntu2
  Version table:
 *** 3.2-1~exp5ubuntu2 0
        500 http://archive.ubuntu.com/ubuntu/ raring/universe amd64 Packages
        100 /var/lib/dpkg/status

llvm-3.2:
  Installed: 3.2-2ubuntu4
  Candidate: 3.2-2ubuntu4
  Version table:
 *** 3.2-2ubuntu4 0
        500 http://archive.ubuntu.com/ubuntu/ raring/universe amd64 Packages
        100 /var/lib/dpkg/status

gcc:
  Installed: 4:4.7.2-1ubuntu8
  Candidate: 4:4.7.2-1ubuntu8
  Version table:
 *** 4:4.7.2-1ubuntu8 0
        500 http://archive.ubuntu.com/ubuntu/ raring/main amd64 Packages
        100 /var/lib/dpkg/status

This type of error doesn't occur with .c source files (using clang of course).
Clang++ used to work on raring perfectly till around 09 march (I think. However it always worked on my raring installation)
If you need more information, please feel free to contact me.
Thanks for your precious time and work,
Have a nice day

Giulio