diff --git a/runtime/libprofile/BlockProfiling.c b/runtime/libprofile/BlockProfiling.c
new file mode 100644
index 0000000..2b1b011
--- /dev/null
+++ b/runtime/libprofile/BlockProfiling.c
@@ -0,0 +1,45 @@
+/*===-- BlockProfiling.c - Support library for block profiling ------------===*\
+|*
+|*                     The LLVM Compiler Infrastructure
+|*
+|* This file was developed by the LLVM research group and is distributed under
+|* the University of Illinois Open Source License. See LICENSE.TXT for details.
+|* 
+|*===----------------------------------------------------------------------===*|
+|* 
+|* This file implements the call back routines for the block profiling
+|* instrumentation pass.  This should be used with the -insert-block-profiling
+|* LLVM pass.
+|*
+\*===----------------------------------------------------------------------===*/
+
+#include "Profiling.h"
+#include <stdlib.h>
+
+static unsigned *ArrayStart;
+static unsigned NumElements;
+
+/* BlockProfAtExitHandler - When the program exits, just write out the profiling
+ * data.
+ */
+static void BlockProfAtExitHandler() {
+  /* Note that if this were doing something more intelligent with the
+   * instrumentation, we could do some computation here to expand what we
+   * collected into simple block profiles. (Or we could do it in llvm-prof.)
+   * Regardless, we directly count each block, so no expansion is necessary.
+   */
+  write_profiling_data(BlockInfo, ArrayStart, NumElements);
+}
+
+
+/* llvm_start_block_profiling - This is the main entry point of the block
+ * profiling library.  It is responsible for setting up the atexit handler.
+ */
+int llvm_start_block_profiling(int argc, const char **argv,
+                               unsigned *arrayStart, unsigned numElements) {
+  int Ret = save_arguments(argc, argv);
+  ArrayStart = arrayStart;
+  NumElements = numElements;
+  atexit(BlockProfAtExitHandler);
+  return Ret;
+}