diff --git a/libc/Android.mk b/libc/Android.mk
index 7d438f4..3e37ca7 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -548,13 +548,6 @@
   libc_common_cflags += -DMALLOC_ALIGNMENT=$(BOARD_MALLOC_ALIGNMENT)
 endif
 
-# Define ANDROID_SMP appropriately.
-ifeq ($(TARGET_CPU_SMP),true)
-    libc_common_cflags += -DANDROID_SMP=1
-else
-    libc_common_cflags += -DANDROID_SMP=0
-endif
-
 # Define some common conlyflags
 libc_common_conlyflags := \
     -std=gnu99
diff --git a/libc/private/bionic_atomic_arm.h b/libc/private/bionic_atomic_arm.h
index 2156e6a..0cb832f 100644
--- a/libc/private/bionic_atomic_arm.h
+++ b/libc/private/bionic_atomic_arm.h
@@ -17,12 +17,7 @@
 #define BIONIC_ATOMIC_ARM_H
 
 __ATOMIC_INLINE__ void __bionic_memory_barrier() {
-#if defined(ANDROID_SMP) && ANDROID_SMP == 1
   __asm__ __volatile__ ( "dmb ish" : : : "memory" );
-#else
-  /* A simple compiler barrier. */
-  __asm__ __volatile__ ( "" : : : "memory" );
-#endif
 }
 
 /* Compare-and-swap, without any explicit barriers. Note that this function
diff --git a/libc/private/bionic_atomic_inline.h b/libc/private/bionic_atomic_inline.h
index b834a27..f8032c3 100644
--- a/libc/private/bionic_atomic_inline.h
+++ b/libc/private/bionic_atomic_inline.h
@@ -30,10 +30,6 @@
  *   on SMP systems emits an appropriate instruction.
  */
 
-#if !defined(ANDROID_SMP)
-# error "Must define ANDROID_SMP before including atomic-inline.h"
-#endif
-
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/libc/private/bionic_atomic_mips.h b/libc/private/bionic_atomic_mips.h
index 5e08116..83f75fe 100644
--- a/libc/private/bionic_atomic_mips.h
+++ b/libc/private/bionic_atomic_mips.h
@@ -21,12 +21,7 @@
  */
 
 __ATOMIC_INLINE__ void __bionic_memory_barrier() {
-#if defined(ANDROID_SMP) && ANDROID_SMP == 1
   __asm__ __volatile__ ( "sync" : : : "memory" );
-#else
-  /* A simple compiler barrier. */
-  __asm__ __volatile__ ( "" : : : "memory" );
-#endif
 }
 
 /* Compare-and-swap, without any explicit barriers. Note that this function
diff --git a/libc/private/bionic_atomic_x86.h b/libc/private/bionic_atomic_x86.h
index 89639c8..e63df93 100644
--- a/libc/private/bionic_atomic_x86.h
+++ b/libc/private/bionic_atomic_x86.h
@@ -20,12 +20,7 @@
  * platform for a multi-core device.
  */
 __ATOMIC_INLINE__ void __bionic_memory_barrier() {
-#if defined(ANDROID_SMP) && ANDROID_SMP == 1
   __asm__ __volatile__ ( "mfence" : : : "memory" );
-#else
-  /* A simple compiler barrier. */
-  __asm__ __volatile__ ( "" : : : "memory" );
-#endif
 }
 
 /* Compare-and-swap, without any explicit barriers. Note that this function