diff '--color=auto' -rupN maxcso.orig/Makefile maxcso/Makefile
--- maxcso.orig/Makefile	2021-09-02 11:23:11.924222645 +0200
+++ maxcso/Makefile	2021-09-02 11:24:58.177464161 +0200
@@ -5,8 +5,9 @@ MANDIR ?= $(PREFIX)/share/man
 CC ?= gcc
 CXX ?= g++
 
-CFLAGS ?= -O2
-CXXFLAGS ?= $(CFLAGS)
+CFLAGS ?= ${CFLAGS}
+CXXFLAGS ?= ${CXXFLAGS}
+LDFLAGS ?= ${LDFLAGS}
 
 SRC_CFLAGS += -W -Wall -Wextra -Wno-implicit-function-declaration -DNDEBUG=1
 SRC_CXXFLAGS += -W -Wall -Wextra -std=c++11 -Izopfli/src -I7zip -DNDEBUG=1 \
@@ -32,7 +33,7 @@ ZOPFLI_C_OBJ = $(ZOPFLI_C_SRC:.c=.o)
 
 # TODO: Perhaps detect and use system libdeflate if available.
 maxcso: $(SRC_CXX_OBJ) $(CLI_CXX_OBJ) $(ZOPFLI_C_OBJ) 7zip/7zip.a libdeflate/libdeflate.a
-	$(CXX) -o $@ $(SRC_CXXFLAGS) $(CXXFLAGS) $^ -luv -llz4 -lz
+	$(CXX) -o $@ $(SRC_CXXFLAGS) $(CXXFLAGS) $(LDFLAGS) $^ -luv -llz4 -lz
 
 7zip/7zip.a:
 	$(MAKE) -C 7zip 7zip.a