diff --git a/include/atomic.h b/include/atomic.h
index 227c4cdf27..866c11c11f 100644
--- a/include/atomic.h
+++ b/include/atomic.h
@@ -108,7 +108,7 @@
 
 
 #ifndef atomic_read_barrier
-# define atomic_read_barrier() atomic_full_barrier ()
+# define atomic_read_barrier() __atomic_thread_fence (__ATOMIC_ACQUIRE);
 #endif
 
 
diff --git a/sysdeps/alpha/atomic-machine.h b/sysdeps/alpha/atomic-machine.h
index a1d74a930e..198f5dc037 100644
--- a/sysdeps/alpha/atomic-machine.h
+++ b/sysdeps/alpha/atomic-machine.h
@@ -22,5 +22,4 @@
 /* XXX Is this actually correct?  */
 #define ATOMIC_EXCHANGE_USES_CAS 1
 
-#define atomic_read_barrier()	__asm ("mb" : : : "memory");
 #define atomic_write_barrier()	__asm ("wmb" : : : "memory");
diff --git a/sysdeps/generic/malloc-machine.h b/sysdeps/generic/malloc-machine.h
index 195fd8c5e6..4fb8e809cc 100644
--- a/sysdeps/generic/malloc-machine.h
+++ b/sysdeps/generic/malloc-machine.h
@@ -22,10 +22,6 @@
 
 #include <atomic.h>
 
-#ifndef atomic_read_barrier
-# define atomic_read_barrier() atomic_full_barrier ()
-#endif
-
 #ifndef atomic_write_barrier
 # define atomic_write_barrier() atomic_full_barrier ()
 #endif
diff --git a/sysdeps/powerpc/atomic-machine.h b/sysdeps/powerpc/atomic-machine.h
index 65c774a064..e173b61e9c 100644
--- a/sysdeps/powerpc/atomic-machine.h
+++ b/sysdeps/powerpc/atomic-machine.h
@@ -37,23 +37,11 @@
 #endif
 
 #ifdef _ARCH_PWR4
-/*
- * Newer powerpc64 processors support the new "light weight" sync (lwsync)
- * So if the build is using -mcpu=[power4,power5,power5+,970] we can
- * safely use lwsync.
- */
-# define atomic_read_barrier()	__asm ("lwsync" ::: "memory")
 /*
  * "light weight" sync can also be used for the release barrier.
  */
 # define atomic_write_barrier()	__asm ("lwsync" ::: "memory")
 #else
-/*
- * Older powerpc32 processors don't support the new "light weight"
- * sync (lwsync).  So the only safe option is to use normal sync
- * for all powerpc32 applications.
- */
-# define atomic_read_barrier()	__asm ("sync" ::: "memory")
 # define atomic_write_barrier()	__asm ("sync" ::: "memory")
 #endif
 
diff --git a/sysdeps/x86/atomic-machine.h b/sysdeps/x86/atomic-machine.h
index 97d9c99fa6..f46a0868e3 100644
--- a/sysdeps/x86/atomic-machine.h
+++ b/sysdeps/x86/atomic-machine.h
@@ -31,7 +31,6 @@
 
 #define ATOMIC_EXCHANGE_USES_CAS	0
 
-#define atomic_read_barrier() __asm ("" ::: "memory")
 #define atomic_write_barrier() __asm ("" ::: "memory")
 
 #define atomic_spin_nop() __asm ("pause")