diff --git a/Makefile.in b/Makefile.in
index dd8f73c..c698e4b 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -311,11 +311,11 @@ $(ARCHIVEOBJS): $(ARCHIVESRCS) $(ARCHIVEHDRS)
 	$(COMPILE) $(GEN_OPT) $(VEC_FLAGS) $(CPPFLAGS) $(@:.o=.c) -o $@
 
 $(PJPGOBJS): $(PJPGSRCS) $(PJPGHDRS)
-	$(COMPILE_cpp) $(COMMON_VEC_FLAGS) @SSE_OPT_FLAGS@ -O2 -fsched-spec-load \
+	$(COMPILE_cpp) $(COMMON_VEC_FLAGS) @SSE_OPT_FLAGS@ @USE_CLANG_AS@ -O2 -fsched-spec-load \
 	$(VEC_FLAGS) -DBUILD_LIB $(COMMON_CPPFLAGS_cpp) $(@:.o=.cpp) -o $@
 
 $(DISPACKOBJS): $(DISPACKSRCS) $(DISPACKHDRS)
-	$(COMPILE_cpp) $(COMMON_VEC_FLAGS) @DEBUG_STATS_CPPFLAGS@ @SSE_OPT_FLAGS@ -O2 -fsched-spec-load \
+	$(COMPILE_cpp) $(COMMON_VEC_FLAGS) @DEBUG_STATS_CPPFLAGS@ @SSE_OPT_FLAGS@ @USE_CLANG_AS@ -O2 -fsched-spec-load \
 	-Wno-variadic-macros $(VEC_FLAGS) $(COMMON_CPPFLAGS_cpp) $(@:.o=.cpp) -o $@
 
 $(SKEIN_BLOCK_OBJ): $(SKEIN_BLOCK_SRC)
@@ -383,7 +383,7 @@ $(PROGOBJS): $(PROGSRCS) $(PROGHDRS)
 	$(COMPILE) $(GEN_OPT) $(LOOP_OPTFLAGS) $(CPPFLAGS) $(@:.o=.c) -o $@
 
 $(LIBBSCLIB):
-	(cd $(LIBBSCDIR); make CC=$(GPP))
+	(cd $(LIBBSCDIR); make CC=$(GPP) OPTFLAGS="@SSE_OPT_FLAGS@ @USE_CLANG_AS@")
 
 $(LIB): $(OBJS)  $(LIBBSCLIB)
 	$(LINK.LIB) -Wl,-soname$(LIB).$(LIBVER) -o $(LIB).$(LIBVER) $(OBJS) $(LDLIBS)
diff --git a/bsc/makefile b/bsc/makefile
index 5fc9a3e..7479291 100644
--- a/bsc/makefile
+++ b/bsc/makefile
@@ -24,7 +24,7 @@ CFLAGS = -g -Wall -fPIC
 CFLAGS += -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
 
 # Comment out CFLAGS line below to disable optimizations
-CFLAGS += -O3 -fomit-frame-pointer -fstrict-aliasing 
+CFLAGS += -O2 -fomit-frame-pointer -fstrict-aliasing -ftree-vectorize $(OPTFLAGS)
 
 # Comment out CFLAGS line below to disable OpenMP optimizations
 CFLAGS += -fopenmp -DLIBBSC_OPENMP_SUPPORT
diff --git a/config b/config
index f5de671..de7434c 100755
--- a/config
+++ b/config
@@ -102,6 +102,8 @@ soname_opt="soname,"
 rpath="-R"
 dtag_val=',--enable-new-dtags'
 lrt="-lrt"
+default_opt="O3"
+max_opt="O3"
 
 if [ -x /bin/echo ]
 then
@@ -388,6 +390,7 @@ then
 	rpath="-rpath,"
 	dtag_val=""
 	lrt=""
+	max_opt="O2"
 fi
 
 # Detect OpenSSL library
@@ -718,6 +721,7 @@ s#@YASM_GAS@#${yasm_params_gas}#g
 s#@RPATH@#${rpath}#g
 s#@LRT@#${lrt}#g
 s#soname#${soname_opt}#g
+s#${default_opt}#${max_opt}#g
 s#@DTAGS@#${dtag_val}#g
 s#@${linkvar}@#\\\$\\(${typ}_${linkvar}\\)#g
 s#@${compilevar}@#\\\$\\(${typ}_${compilevar}\\)#g