diff --git a/mocks/include/lib/libc/cdefs.h b/mocks/include/lib/libc/cdefs.h
new file mode 100644
index 0000000..0d00722
--- /dev/null
+++ b/mocks/include/lib/libc/cdefs.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef CDEFS_H
+#define CDEFS_H
+
+#define __dead2		__attribute__((__noreturn__))
+#define __deprecated	__attribute__((__deprecated__))
+#define __packed	__attribute__((__packed__))
+#define __used		__attribute__((__used__))
+#define __unused	__attribute__((__unused__))
+#define __aligned(x)	__attribute__((__aligned__(x)))
+#define __section(x)	__attribute__((__section__(x)))
+#if RECLAIM_INIT_CODE
+/*
+ * Add each function to a section that is unique so the functions can still
+ * be garbage collected
+ */
+#define __init		__section(".text.init." __FILE__ "." __XSTRING(__LINE__))
+#else
+#define __init
+#endif
+
+#define __printflike(fmtarg, firstvararg) \
+		__attribute__((__format__ (__printf__, fmtarg, firstvararg)))
+
+#define __weak_reference(sym, alias)	\
+	__asm__(".weak alias");		\
+	__asm__(".equ alias, sym")
+
+#define __STRING(x)	#x
+#define __XSTRING(x)	__STRING(x)
+
+#endif /* CDEFS_H */