diff --git a/arch/powerpc/include/asm/system.h b/arch/powerpc/include/asm/system.h
index 2a4be19a92c43275343fb5ed808667c92117bb92..f612798e1c9353f0a0044a9c7e6203e10da11b43 100644
--- a/arch/powerpc/include/asm/system.h
+++ b/arch/powerpc/include/asm/system.h
@@ -531,7 +531,7 @@ __cmpxchg_local(volatile void *ptr, unsigned long old, unsigned long new,
 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 #endif
 
-#define arch_align_stack(x) (x)
+extern unsigned long arch_align_stack(unsigned long sp);
 
 /* Used in very early kernel initialization. */
 extern unsigned long reloc_offset(void);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 8ede428e76c007d7a54f240749a866de24f8b12d..69b9d2d3cb84a353dc5cc25a1422e698f17a10f2 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -35,6 +35,8 @@
 #include <linux/utsname.h>
 #include <linux/ftrace.h>
 #include <linux/kernel_stat.h>
+#include <linux/personality.h>
+#include <linux/random.h>
 
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
@@ -1138,3 +1140,10 @@ void thread_info_cache_init(void)
 }
 
 #endif /* THREAD_SHIFT < PAGE_SHIFT */
+
+unsigned long arch_align_stack(unsigned long sp)
+{
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+		sp -= get_random_int() & ~PAGE_MASK;
+	return sp & ~0xf;
+}