--- Makefile.orig	2021-10-19 02:19:29 UTC
+++ Makefile
@@ -2,11 +2,13 @@ DIR_INC := ./inc
 DIR_SRC := ./src
 DIR_OBJ := ./obj
 
-PREFIX ?= /usr/local
-BINDIR ?= $(PREFIX)/bin
-INCLUDE_DIRS ?=
-LIBRARY_DIRS ?=
+PREFIX	?= /usr/local
+BINDIR	?= $(PREFIX)/bin
+INCLUDE_DIRS	?=
+LIBRARY_DIRS	?=
 
+STRIP	?= strip
+
 SRC := $(wildcard ${DIR_SRC}/*.cpp)
 OBJ := $(patsubst %.cpp,${DIR_OBJ}/%.o,$(notdir ${SRC}))
 
@@ -15,15 +17,19 @@ TARGET := fastp
 BIN_TARGET := ${TARGET}
 
 CXX ?= g++
-CXXFLAGS := -std=c++11 -pthread -g -O3 -I${DIR_INC} $(foreach includedir,$(INCLUDE_DIRS),-I$(includedir)) ${CXXFLAGS}
+# Optional flags that the user can override by setting CXXFLAGS in the
+# env or make argument
+CXXFLAGS ?= -g -O3
+# Required flags
+CXXFLAGS += -std=c++11 -I${DIR_INC} $(foreach includedir,$(INCLUDE_DIRS),-I$(includedir))
 LIBS := -lisal -ldeflate -lpthread
 STATIC_FLAGS := -static -Wl,--no-as-needed -pthread
-LD_FLAGS := $(foreach librarydir,$(LIBRARY_DIRS),-L$(librarydir)) $(LIBS) $(LD_FLAGS)
+# Append required flags to standard LDFLAGS from env
+LDFLAGS += $(foreach librarydir,$(LIBRARY_DIRS),-L$(librarydir)) $(LIBS)
 STATIC_LD_FLAGS := $(foreach librarydir,$(LIBRARY_DIRS),-L$(librarydir)) $(STATIC_FLAGS) $(LIBS) $(STATIC_LD_FLAGS)
 
-
 ${BIN_TARGET}:${OBJ}
-	$(CXX) $(OBJ) -o $@ $(LD_FLAGS)
+	$(CXX) $(OBJ) -o $@ $(LDFLAGS)
 
 static:${OBJ}
 	$(CXX) $(OBJ) -o ${BIN_TARGET} $(STATIC_LD_FLAGS)
@@ -49,6 +55,11 @@ make_obj_dir:
 		mkdir $(DIR_OBJ) ; \
 	fi
 
+# Respect DESTDIR for staged installs (used by most package managers)
 install:
-	install $(TARGET) $(BINDIR)/$(TARGET)
+	install $(TARGET) $(DESTDIR)$(BINDIR)/$(TARGET)
 	@echo "Installed."
+
+# Many package managers use install-strip target if debugging is not enabled
+install-strip: install
+	$(STRIP) $(DESTDIR)$(BINDIR)/$(TARGET)