Error: Invalid file format (bad magic) with -fprofile-instr-use

Hi all,

Flag "-fprofile-instr-use" generates error given below.
This issue occurs even if we build llvm,clang and compiler-rt using cmake or
configure.
Please let me know your inputs to resolve this issue

Error:error: Could not read profile: Invalid file format (bad magic)

Thanks,

*Steps to reproduce this issue:*
$ clang -O2 -fprofile-instr-generate hello.c -o c1.out

$ ls -rlt
-rw-r--r-- 1 root root 70 Jul 11 10:10 hello.c
-rwxr-xr-x 1 root root 15793 Jul 11 10:10 c1.out
-rw-r--r-- 1 root root 12203204 Jul 11 10:10 *gmon.out*

$ ./c1.out
Hello world

$ ls -rlt
-rw-r--r-- 1 root root 70 Jul 11 10:10 hello.c
-rwxr-xr-x 1 root root 15793 Jul 11 10:10 c1.out
-rw-r--r-- 1 root root 12203204 Jul 11 10:10 *gmon.out*
-rw-r--r-- 1 root root 104 Jul 11 10:10 *default.profraw*

$ clang -O2 -fprofile-instr-use=default.profraw hello.c -o c2.out
error: Could not read profile: Invalid file format (bad magic)
1 error generated.

*Clang version (July 10th-2014 build from stage): *
$ clang -v
clang -v
clang version 3.5.0 (llvm.org/git/clang.git
5f9d646cba20f309bb69c6c358996d71912c54cd) (llvm.org/git/llvm.git
dc90a3ab8ffc841a442888940635306de6131d2f)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.2
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64

*OS:* Ubuntu 14.04

*LLVM configure:* ../llvm/configure --enable-profiling --enable-optimized
--enable-shared --disable-debug-runtime --enable-targets=x86

The .profraw file needs to be transformed into a .profdata file before use. See step 3 here:

http://clang.llvm.org/docs/UsersManual.html#profiling-with-instrumentation