diff --git a/src/lib/libgcc.c b/src/lib/libgcc.c
new file mode 100644
index 0000000..14685be
--- /dev/null
+++ b/src/lib/libgcc.c
@@ -0,0 +1,56 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2015 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc.
+ */
+
+#include <types.h>
+
+/*
+ * Provide platform-independent backend implementation for __builtin_clz() in
+ * <lib.h> in case GCC does not have an assembly version for this arch.
+ */
+
+#if !IS_ENABLED(CONFIG_ARCH_X86) /* work around lack of --gc-sections on x86 */
+int __clzsi2(u32 a);
+int __clzsi2(u32 a)
+{
+	static const u8 four_bit_table[] = {
+		[0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
+		[0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
+		[0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
+		[0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
+	};
+	int r = 0;
+
+	if (!(a & (0xffff << 16))) {
+		r += 16;
+		a <<= 16;
+	}
+
+	if (!(a & (0xff << 24))) {
+		r += 8;
+		a <<= 8;
+	}
+
+	if (!(a & (0xf << 28))) {
+		r += 4;
+		a <<= 4;
+	}
+
+	return r + four_bit_table[a >> 28];
+}
+#endif