diff --git a/compiler-rt/lib/builtins/arm/sync-ops.h b/compiler-rt/lib/builtins/arm/sync-ops.h
--- a/compiler-rt/lib/builtins/arm/sync-ops.h
+++ b/compiler-rt/lib/builtins/arm/sync-ops.h
@@ -14,6 +14,14 @@
 
 #include "../assembly.h"
 
+#if __ARM_ARCH >= 7
+#define DMB dmb
+#elif __ARM_ARCH >= 6
+#define DMB mcr p15, #0, r0, c7, c10, #5
+#else
+#error DMB is only supported on ARMv6+
+#endif
+
 #define SYNC_OP_4(op)                                                          \
   .p2align 2;                                                                  \
   .syntax unified;                                                             \
diff --git a/compiler-rt/lib/builtins/assembly.h b/compiler-rt/lib/builtins/assembly.h
--- a/compiler-rt/lib/builtins/assembly.h
+++ b/compiler-rt/lib/builtins/assembly.h
@@ -189,14 +189,6 @@
   JMP(ip)
 #endif
 
-#if __ARM_ARCH >= 7
-#define DMB dmb
-#elif __ARM_ARCH >= 6
-#define DMB mcr p15, #0, r0, c7, c10, #5
-#else
-#error only supported on ARMv6+
-#endif
-
 #if defined(USE_THUMB_2)
 #define WIDE(op) op.w
 #else