diff --git a/include/asm-cris/system.h b/include/asm-cris/system.h
index 1d63c2aa8ec2cf295245b97c44755f6fa4299c21..b1c593b6dbff163df5118bc6ba8c5841148fd43a 100644
--- a/include/asm-cris/system.h
+++ b/include/asm-cris/system.h
@@ -8,7 +8,6 @@
  */
 
 extern struct task_struct *resume(struct task_struct *prev, struct task_struct *next, int);
-#define prepare_to_switch()     do { } while(0)
 #define switch_to(prev,next,last) last = resume(prev,next, \
 					 (int)&((struct task_struct *)0)->thread)
 
diff --git a/include/asm-frv/system.h b/include/asm-frv/system.h
index f72ff0c4dc0b9050a580e0c4dba61b8a36b7b129..1734ed91bcdcdb7f0136f10bd9f14fc8e9d535b3 100644
--- a/include/asm-frv/system.h
+++ b/include/asm-frv/system.h
@@ -18,8 +18,6 @@
 
 struct thread_struct;
 
-#define prepare_to_switch()    do { } while(0)
-
 /*
  * switch_to(prev, next) should switch from task `prev' to `next'
  * `prev' will never be the same as `next'.
diff --git a/include/asm-h8300/system.h b/include/asm-h8300/system.h
index dfe96c7121cfe3ad6742fbb93ebea1bb6aea85be..8e81cf665e75ea3406b2d4a79f7a002671aa52f8 100644
--- a/include/asm-h8300/system.h
+++ b/include/asm-h8300/system.h
@@ -4,8 +4,6 @@
 #include <linux/config.h> /* get configuration macros */
 #include <linux/linkage.h>
 
-#define prepare_to_switch()	do { } while(0)
-
 /*
  * switch_to(n) should switch tasks to task ptr, first checking that
  * ptr isn't the current task, in which case it does nothing.  This
diff --git a/include/asm-m32r/system.h b/include/asm-m32r/system.h
index d6a2c613be68abff0d8a8d58de9bddbbf2800ac2..c5ab5da56d21acb42dfb4c18e5bbdd8151aa58f8 100644
--- a/include/asm-m32r/system.h
+++ b/include/asm-m32r/system.h
@@ -22,10 +22,6 @@
  * `next' and `prev' should be struct task_struct, but it isn't always defined
  */
 
-#ifndef CONFIG_SMP
-#define prepare_to_switch()  do { } while(0)
-#endif	/* not CONFIG_SMP */
-
 #define switch_to(prev, next, last)  do { \
 	register unsigned long  arg0 __asm__ ("r0") = (unsigned long)prev; \
 	register unsigned long  arg1 __asm__ ("r1") = (unsigned long)next; \
diff --git a/include/asm-v850/system.h b/include/asm-v850/system.h
index 107decbd6e6cfc038a1729a77154f97ed5f65204..7091af4b786677ca176f08d01127cc6f69361185 100644
--- a/include/asm-v850/system.h
+++ b/include/asm-v850/system.h
@@ -18,8 +18,6 @@
 #include <asm/ptrace.h>
 
 
-#define prepare_to_switch()	do { } while (0)
-
 /*
  * switch_to(n) should switch tasks to task ptr, first checking that
  * ptr isn't the current task, in which case it does nothing.
diff --git a/include/asm-xtensa/system.h b/include/asm-xtensa/system.h
index 9284867f1cb90616cfba4af95b14f42f3059cdd5..b29f7ae6a08ae5a872be5ca443844a4f01dd7362 100644
--- a/include/asm-xtensa/system.h
+++ b/include/asm-xtensa/system.h
@@ -111,8 +111,6 @@ extern void *_switch_to(void *last, void *next);
 
 #endif	/* __ASSEMBLY__ */
 
-#define prepare_to_switch()	do { } while(0)
-
 #define switch_to(prev,next,last)		\
 do {						\
 	clear_cpenable();			\