--- a/auto/cc/conf
+++ b/auto/cc/conf
@@ -105,7 +105,6 @@ fi
 
 CFLAGS="$CFLAGS $NGX_CC_OPT"
 
-
 if [ "$NGX_PLATFORM" != win32 ]; then
 
     if test -n "$NGX_LD_OPT"; then
@@ -125,6 +124,19 @@ if [ "$NGX_PLATFORM" != win32 ]; then
         fi
     fi
 
+
+    ngx_feature="gcc builtin atomic operations"
+    ngx_feature_name=NGX_HAVE_GCC_ATOMIC
+    ngx_feature_run=no
+    ngx_feature_incs=
+    ngx_feature_path=
+    ngx_feature_libs=
+    ngx_feature_test="long  n;
+                      __sync_bool_compare_and_swap(&n, 0, 1);
+                      __sync_fetch_and_add(&n, 1);"
+    . auto/feature
+
+
     ngx_feature="gcc variadic macros"
     ngx_feature_name="NGX_HAVE_GCC_VARIADIC_MACROS"
     ngx_feature_run=yes

--- a/auto/cc/gcc
+++ b/auto/cc/gcc
@@ -90,7 +90,6 @@ case $CPU in
         # build 32-bit UltraSparc binary
         CPU_OPT="-m32"
         CORE_LINK="$CORE_LINK -m32"
-        CC_AUX_FLAGS="$CC_AUX_FLAGS -m32"
         NGX_CPU_CACHE_LINE=64
     ;;
 
@@ -98,7 +97,6 @@ case $CPU in
         # build 64-bit UltraSparc binary
         CPU_OPT="-m64"
         CORE_LINK="$CORE_LINK -m64"
-        CC_AUX_FLAGS="$CC_AUX_FLAGS -m64"
         NGX_CPU_CACHE_LINE=64
     ;;
 
@@ -108,12 +106,12 @@ case $CPU in
         CPU_OPT="$CPU_OPT -falign-functions=32 -falign-labels=32"
         CPU_OPT="$CPU_OPT -falign-loops=32 -falign-jumps=32"
         CORE_LINK="$CORE_LINK -m64"
-        CC_AUX_FLAGS="$CC_AUX_FLAGS -m64"
         NGX_CPU_CACHE_LINE=128
     ;;
 
 esac
 
+CC_AUX_FLAGS="$CC_AUX_FLAGS $CPU_OPT"
 
 case "$NGX_GCC_VER" in
     2.7*)

--- a/src/os/unix/ngx_atomic.h
+++ b/src/os/unix/ngx_atomic.h
@@ -60,10 +60,40 @@ typedef uint32_t                    ngx_
 typedef volatile ngx_atomic_uint_t  ngx_atomic_t;
 
 
-#else /* !(NGX_DARWIN) */
+#elif (NGX_HAVE_GCC_ATOMIC)
+
+/* GCC 4.1 builtin atomic operations */
+
+#define NGX_HAVE_ATOMIC_OPS  1
+
+typedef long                        ngx_atomic_int_t;
+typedef unsigned long               ngx_atomic_uint_t;
+
+#if (NGX_PTR_SIZE == 8)
+#define NGX_ATOMIC_T_LEN            (sizeof("-9223372036854775808") - 1)
+#else
+#define NGX_ATOMIC_T_LEN            (sizeof("-2147483648") - 1)
+#endif
+
+typedef volatile ngx_atomic_uint_t  ngx_atomic_t;
 
 
-#if ( __i386__ || __i386 )
+#define ngx_atomic_cmp_set(lock, old, set)                                    \
+    __sync_bool_compare_and_swap(lock, old, set)
+
+#define ngx_atomic_fetch_add(value, add)                                      \
+    __sync_fetch_and_add(value, add)
+
+#define ngx_memory_barrier()        __sync_synchronize()
+
+#if ( __i386__ || __i386 || __amd64__ || __amd64 )
+#define ngx_cpu_pause()             __asm__ ("pause")
+#else
+#define ngx_cpu_pause()
+#endif
+
+
+#elif ( __i386__ || __i386 )
 
 typedef int32_t                     ngx_atomic_int_t;
 typedef uint32_t                    ngx_atomic_uint_t;
@@ -203,9 +233,6 @@ typedef volatile ngx_atomic_uint_t  ngx_
 
 #include "ngx_gcc_atomic_ppc.h"
 
-
-#endif
-
 #endif