diff --git a/Makefile.system b/Makefile.system
index 31cdd12b2..d68353b12 100644
--- a/Makefile.system
+++ b/Makefile.system
@@ -784,6 +784,14 @@ endif
 ifeq ($(F_COMPILER), FLANG)
 CCOMMON_OPT += -DF_INTERFACE_FLANG
 FCOMMON_OPT += -Mrecursive -Kieee
+ifeq ($(OSNAME), Linux)
+ifeq ($(ARCH), x86_64)
+FLANG_VENDOR := $(shell expr `$(FC) --version|cut -f 1 -d "."|head -1`)
+ifeq ($(FLANG_VENDOR),AOCC)
+FCOMMON_OPT += -fno-unroll-loops
+endif
+endif
+endif
 ifdef BINARY64
 ifdef INTERFACE64
 ifneq ($(INTERFACE64), 0)
@@ -1271,11 +1279,7 @@ endif
 
 override CFLAGS     += $(COMMON_OPT) $(CCOMMON_OPT) -I$(TOPDIR)
 override PFLAGS     += $(COMMON_OPT) $(CCOMMON_OPT) -I$(TOPDIR) -DPROFILE $(COMMON_PROF)
-ifeq ($(F_COMPILER),FLANG)
-override FFLAGS     += $(filter-out -O2 -O3,$(COMMON_OPT)) -O1 $(FCOMMON_OPT)
-else
 override FFLAGS     += $(COMMON_OPT) $(FCOMMON_OPT)
-endif
 override FPFLAGS    += $(FCOMMON_OPT) $(COMMON_PROF)
 #MAKEOVERRIDES =