diff --git a/auto/cc/sunc b/auto/cc/sunc
index 1d3c68700..69e6c2c71 100644
--- a/auto/cc/sunc
+++ b/auto/cc/sunc
@@ -6,6 +6,8 @@
 # Sun C 5.8 2005/10/13                    Sun Studio 11
 # Sun C 5.9 SunOS_i386 2007/05/03         Sun Studio 12
 # Sun C 5.9 SunOS_sparc 2007/05/03
+# Sun C 5.10 SunOS_i386 2009/06/03        Sun Studio 12.1
+# Sun C 5.11 SunOS_i386 2010/08/13        Sun Studio 12.2
 
 NGX_SUNC_VER=`$CC -V 2>&1 | grep 'Sun C' 2>&1 \
                           | sed -e 's/^.* Sun C \(.*\)/\1/'`
@@ -57,9 +59,19 @@ esac
 
 # optimizations
 
+# 20736 == 0x5100, Sun Studio 12.1
+
+if [ "$ngx_sunc_ver" -ge 20736 ]; then
+    ngx_fast="-fast"
+
+else
+    # older versions had problems with bit-fields
+    ngx_fast="-fast -xalias_level=any"
+fi
+
 IPO=-xipo
-CFLAGS="$CFLAGS -fast $IPO"
-CORE_LINK="$CORE_LINK -fast $IPO"
+CFLAGS="$CFLAGS $ngx_fast $IPO"
+CORE_LINK="$CORE_LINK $ngx_fast $IPO"
 
 
 case $CPU in
@@ -126,15 +138,15 @@ CFLAGS="$CFLAGS $CPU_OPT"
 
 
 if [ ".$PCRE_OPT" = "." ]; then
-    PCRE_OPT="-fast $IPO $CPU_OPT"
+    PCRE_OPT="$ngx_fast $IPO $CPU_OPT"
 fi
 
 if [ ".$MD5_OPT" = "." ]; then
-    MD5_OPT="-fast $IPO $CPU_OPT"
+    MD5_OPT="$ngx_fast $IPO $CPU_OPT"
 fi
 
 if [ ".$ZLIB_OPT" = "." ]; then
-    ZLIB_OPT="-fast $IPO $CPU_OPT"
+    ZLIB_OPT="$ngx_fast $IPO $CPU_OPT"
 fi