diff --git a/lib/powisf2.c b/lib/powisf2.c
new file mode 100644
index 0000000..fcaaa1f
--- /dev/null
+++ b/lib/powisf2.c
@@ -0,0 +1,33 @@
+//===-- powisf2.cpp - Implement __powisf2 ---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements __powisf2 for the compiler_rt library.
+//
+//===----------------------------------------------------------------------===//
+
+#include "int_lib.h"
+
+// Returns: a ^ b
+
+float
+__powisf2(float a, si_int b)
+{
+    const int recip = b < 0;
+    float r = 1;
+    while (1)
+    {
+        if (b & 1)
+            r *= a;
+        b /= 2;
+        if (b == 0)
+            break;
+        a *= a;
+    }
+    return recip ? 1/r : r;
+}