diff --git a/memory/mozjemalloc/moz.build b/memory/mozjemalloc/moz.build
index 64ac16b58895..80cfd779bef6 100644
--- a/memory/mozjemalloc/moz.build
+++ b/memory/mozjemalloc/moz.build
@@ -13,11 +13,6 @@ SOURCES += [
 ]
 FINAL_LIBRARY = 'memory'
 
-# See bug 422055.
-if CONFIG['OS_ARCH'] == 'SunOS' and not CONFIG['GNU_CC'] \
-        and CONFIG['MOZ_OPTIMIZE']:
-    CFLAGS += ['-xO5']
-
 DEFINES['MOZ_JEMALLOC_IMPL'] = True
 
 LOCAL_INCLUDES += [