diff --git a/bitcoin-qt.pro b/bitcoin-qt.pro
index 7bab4a4975b..169d2277945 100644
--- a/bitcoin-qt.pro
+++ b/bitcoin-qt.pro
@@ -99,14 +99,14 @@ contains(BITCOIN_NEED_QT_PLUGINS, 1) {
 INCLUDEPATH += src/leveldb/include src/leveldb/helpers
 LIBS += $$PWD/src/leveldb/libleveldb.a $$PWD/src/leveldb/libmemenv.a
 !win32 {
-    genleveldb.commands = cd $$PWD/src/leveldb && $(MAKE) libleveldb.a libmemenv.a
+    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX $(MAKE) OPT=\"$$QMAKE_CXXFLAGS\" libleveldb.a libmemenv.a
 } else {
     # make an educated guess about what the ranlib command is called
     isEmpty(QMAKE_RANLIB) {
         QMAKE_RANLIB = $$replace(QMAKE_STRIP, strip, ranlib)
     }
     LIBS += -lshlwapi
-    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX TARGET_OS=OS_WINDOWS_CROSSCOMPILE $(MAKE) libleveldb.a libmemenv.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libleveldb.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libmemenv.a
+    genleveldb.commands = cd $$PWD/src/leveldb && CC=$$QMAKE_CC CXX=$$QMAKE_CXX TARGET_OS=OS_WINDOWS_CROSSCOMPILE $(MAKE) OPT=\"$$QMAKE_CXXFLAGS\" libleveldb.a libmemenv.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libleveldb.a && $$QMAKE_RANLIB $$PWD/src/leveldb/libmemenv.a
 }
 genleveldb.target = $$PWD/src/leveldb/libleveldb.a
 genleveldb.depends = FORCE
diff --git a/contrib/gitian-descriptors/gitian-win32.yml b/contrib/gitian-descriptors/gitian-win32.yml
index 9df42a0becf..4860a159976 100644
--- a/contrib/gitian-descriptors/gitian-win32.yml
+++ b/contrib/gitian-descriptors/gitian-win32.yml
@@ -51,7 +51,7 @@ script: |
   export LD_PRELOAD=/usr/lib/faketime/libfaketime.so.1
   export FAKETIME=$REFERENCE_DATETIME
   export TZ=UTC
-  $HOME/qt/src/bin/qmake -spec unsupported/win32-g++-cross MINIUPNPC_LIB_PATH=$HOME/build/miniupnpc MINIUPNPC_INCLUDE_PATH=$HOME/build/ BDB_LIB_PATH=$HOME/build/db-4.8.30.NC/build_unix BDB_INCLUDE_PATH=$HOME/build/db-4.8.30.NC/build_unix BOOST_LIB_PATH=$HOME/build/boost_1_50_0/stage/lib BOOST_INCLUDE_PATH=$HOME/build/boost_1_50_0 BOOST_LIB_SUFFIX=-mt-s BOOST_THREAD_LIB_SUFFIX=_win32-mt-s OPENSSL_LIB_PATH=$HOME/build/openssl-1.0.1c OPENSSL_INCLUDE_PATH=$HOME/build/openssl-1.0.1c/include QRENCODE_LIB_PATH=$HOME/build/qrencode-3.2.0/.libs QRENCODE_INCLUDE_PATH=$HOME/build/qrencode-3.2.0 USE_QRCODE=1 INCLUDEPATH=$HOME/build DEFINES=BOOST_THREAD_USE_LIB BITCOIN_NEED_QT_PLUGINS=1 QMAKE_LRELEASE=lrelease QMAKE_CXXFLAGS=-frandom-seed=bitcoin QMAKE_LFLAGS=-frandom-seed=bitcoin USE_BUILD_INFO=1
+  $HOME/qt/src/bin/qmake -spec unsupported/win32-g++-cross MINIUPNPC_LIB_PATH=$HOME/build/miniupnpc MINIUPNPC_INCLUDE_PATH=$HOME/build/ BDB_LIB_PATH=$HOME/build/db-4.8.30.NC/build_unix BDB_INCLUDE_PATH=$HOME/build/db-4.8.30.NC/build_unix BOOST_LIB_PATH=$HOME/build/boost_1_50_0/stage/lib BOOST_INCLUDE_PATH=$HOME/build/boost_1_50_0 BOOST_LIB_SUFFIX=-mt-s BOOST_THREAD_LIB_SUFFIX=_win32-mt-s OPENSSL_LIB_PATH=$HOME/build/openssl-1.0.1c OPENSSL_INCLUDE_PATH=$HOME/build/openssl-1.0.1c/include QRENCODE_LIB_PATH=$HOME/build/qrencode-3.2.0/.libs QRENCODE_INCLUDE_PATH=$HOME/build/qrencode-3.2.0 USE_QRCODE=1 INCLUDEPATH=$HOME/build DEFINES=BOOST_THREAD_USE_LIB BITCOIN_NEED_QT_PLUGINS=1 QMAKE_LRELEASE=lrelease QMAKE_CXXFLAGS=-frandom-seed=bitcoin USE_BUILD_INFO=1
   make $MAKEOPTS
   cp release/bitcoin-qt.exe $OUTDIR/
   #
diff --git a/src/makefile.linux-mingw b/src/makefile.linux-mingw
index c3cbe90bcd5..f6c3a8ad7ee 100644
--- a/src/makefile.linux-mingw
+++ b/src/makefile.linux-mingw
@@ -4,6 +4,9 @@
 
 DEPSDIR:=/usr/i586-mingw32msvc
 
+CC ?= i586-mingw32msvc-gcc
+CXX ?= i586-mingw32msvc-g++
+
 USE_UPNP:=0
 USE_IPV6:=1
 
@@ -58,6 +61,7 @@ LIBS += -l mingwthrd -l kernel32 -l user32 -l gdi32 -l comdlg32 -l winspool -l w
 HEADERS = $(wildcard *.h)
 
 OBJS= \
+    leveldb/libleveldb.a \
     obj/alert.o \
     obj/version.o \
     obj/checkpoints.o \
@@ -95,8 +99,7 @@ all: bitcoind.exe
 DEFS += -I"$(CURDIR)/leveldb/include"
 DEFS += -I"$(CURDIR)/leveldb/helpers"
 leveldb/libleveldb.a:
-	@echo "Building LevelDB ..." && cd leveldb && CC=i586-mingw32msvc-gcc CXX=i586-mingw32msvc-g++ TARGET_OS=OS_WINDOWS_CROSSCOMPILE CXXFLAGS="$(INCLUDEPATHS)" LDFLAGS="$(LIBPATHS)" $(MAKE) libleveldb.a libmemenv.a && i586-mingw32msvc-ranlib libleveldb.a && i586-mingw32msvc-ranlib libmemenv.a && cd ..
-obj/leveldb.o: leveldb/libleveldb.a
+	@echo "Building LevelDB ..." && cd leveldb && TARGET_OS=OS_WINDOWS_CROSSCOMPILE $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(CFLAGS)" libleveldb.a libmemenv.a && i586-mingw32msvc-ranlib libleveldb.a && i586-mingw32msvc-ranlib libmemenv.a && cd ..
 
 obj/build.h: FORCE
 	/bin/sh ../share/genbuild.sh obj/build.h
@@ -104,18 +107,18 @@ version.cpp: obj/build.h
 DEFS += -DHAVE_BUILD_INFO
 
 obj/%.o: %.cpp $(HEADERS)
-	i586-mingw32msvc-g++ -c $(CFLAGS) -o $@ $<
+	$(CXX) -c $(CFLAGS) -o $@ $<
 
 bitcoind.exe: $(OBJS:obj/%=obj/%)
-	i586-mingw32msvc-g++ $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ $(LIBS)
+	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ $(LIBS)
 
 TESTOBJS := $(patsubst test/%.cpp,obj-test/%.o,$(wildcard test/*.cpp))
 
 obj-test/%.o: test/%.cpp $(HEADERS)
-	i586-mingw32msvc-g++ -c $(TESTDEFS) $(CFLAGS) -o $@ $<
+	$(CXX) -c $(TESTDEFS) $(CFLAGS) -o $@ $<
 
 test_bitcoin.exe: $(TESTOBJS) $(filter-out obj/init.o,$(OBJS:obj/%=obj/%))
-	i586-mingw32msvc-g++ $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ -lboost_unit_test_framework-mt-s $(LIBS)
+	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ -lboost_unit_test_framework-mt-s $(LIBS)
 
 
 clean:
diff --git a/src/makefile.mingw b/src/makefile.mingw
index 366d32bd86e..2e092ff6863 100644
--- a/src/makefile.mingw
+++ b/src/makefile.mingw
@@ -15,6 +15,8 @@
 # 'make clean' assumes it is running inside a MSYS shell, and uses 'rm'
 # to remove files.
 
+CXX ?= g++
+
 USE_UPNP:=-
 USE_IPV6:=1
 
@@ -67,6 +69,7 @@ LIBS += -l kernel32 -l user32 -l gdi32 -l comdlg32 -l winspool -l winmm -l shell
 HEADERS = $(wildcard *.h)
 
 OBJS= \
+    leveldb/libleveldb.a \
     obj/alert.o \
     obj/version.o \
     obj/checkpoints.o \
@@ -112,23 +115,21 @@ DEFS += $(addprefix -I,$(CURDIR)/leveldb/include)
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/helpers)
 
 leveldb/libleveldb.a:
-	cd leveldb && $(MAKE) OPT="$(DEBUGFLAGS)" TARGET_OS=NATIVE_WINDOWS libleveldb.a libmemenv.a && cd ..
-
-obj/leveldb.o: leveldb/libleveldb.a
+	cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(CFLAGS)" TARGET_OS=NATIVE_WINDOWS libleveldb.a libmemenv.a && cd ..
 
 obj/%.o: %.cpp $(HEADERS)
-	g++ -c $(CFLAGS) -o $@ $<
+	$(CXX) -c $(CFLAGS) -o $@ $<
 
 bitcoind.exe: $(OBJS:obj/%=obj/%)
-	g++ $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ $(LIBS)
+	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ $(LIBS)
 
 TESTOBJS := $(patsubst test/%.cpp,obj-test/%.o,$(wildcard test/*.cpp))
 
 obj-test/%.o: test/%.cpp $(HEADERS)
-	g++ -c $(TESTDEFS) $(CFLAGS) -o $@ $<
+	$(CXX) -c $(TESTDEFS) $(CFLAGS) -o $@ $<
 
 test_bitcoin.exe: $(TESTOBJS) $(filter-out obj/init.o,$(OBJS:obj/%=obj/%))
-	g++ $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ -lboost_unit_test_framework$(BOOST_SUFFIX) $(LIBS)
+	$(CXX) $(CFLAGS) $(LDFLAGS) -o $@ $(LIBPATHS) $^ -lboost_unit_test_framework$(BOOST_SUFFIX) $(LIBS)
 
 clean:
 	rm -f bitcoind.exe test_bitcoin.exe
diff --git a/src/makefile.osx b/src/makefile.osx
index 8b7c559fa11..cdee7812575 100644
--- a/src/makefile.osx
+++ b/src/makefile.osx
@@ -62,7 +62,7 @@ ifdef RELEASE
 # the same way.
 CFLAGS = -mmacosx-version-min=10.5 -arch i386 -O3
 else
-CFLAGS = -g
+DEBUGFLAGS = -g
 endif
 
 # ppc doesn't work because we don't support big-endian
@@ -70,6 +70,7 @@ CFLAGS += -Wall -Wextra -Wformat -Wformat-security -Wno-unused-parameter \
     $(DEBUGFLAGS) $(DEFS) $(INCLUDEPATHS)
 
 OBJS= \
+    leveldb/libleveldb.a \
     obj/alert.o \
     obj/version.o \
     obj/checkpoints.o \
@@ -130,8 +131,7 @@ LIBS += $(CURDIR)/leveldb/libleveldb.a $(CURDIR)/leveldb/libmemenv.a
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/include)
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/helpers)
 leveldb/libleveldb.a:
-	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) libleveldb.a libmemenv.a && cd ..
-obj/leveldb.o: leveldb/libleveldb.a
+	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(CFLAGS)" libleveldb.a libmemenv.a && cd ..
 
 # auto-generated dependencies:
 -include obj/*.P
@@ -171,5 +171,6 @@ clean:
 	-rm -f obj/*.P
 	-rm -f obj-test/*.P
 	-rm -f obj/build.h
+	-cd leveldb && $(MAKE) clean || true
 
 FORCE:
diff --git a/src/makefile.unix b/src/makefile.unix
index b52a0f8aea1..ece2f59cf5a 100644
--- a/src/makefile.unix
+++ b/src/makefile.unix
@@ -101,6 +101,7 @@ xCXXFLAGS=-O2 -pthread -Wall -Wextra -Wformat -Wformat-security -Wno-unused-para
 xLDFLAGS=$(LDHARDENING) $(LDFLAGS)
 
 OBJS= \
+    leveldb/libleveldb.a \
     obj/alert.o \
     obj/version.o \
     obj/checkpoints.o \
@@ -142,12 +143,12 @@ test check: test_bitcoin FORCE
 #
 # LevelDB support
 #
+MAKEOVERRIDES =
 LIBS += $(CURDIR)/leveldb/libleveldb.a $(CURDIR)/leveldb/libmemenv.a
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/include)
 DEFS += $(addprefix -I,$(CURDIR)/leveldb/helpers)
 leveldb/libleveldb.a:
-	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) libleveldb.a libmemenv.a && cd ..
-obj/leveldb.o: leveldb/libleveldb.a
+	@echo "Building LevelDB ..." && cd leveldb && $(MAKE) CC=$(CC) CXX=$(CXX) OPT="$(xCXXFLAGS)" libleveldb.a libmemenv.a && cd ..
 
 # auto-generated dependencies:
 -include obj/*.P
@@ -187,5 +188,6 @@ clean:
 	-rm -f obj/*.P
 	-rm -f obj-test/*.P
 	-rm -f obj/build.h
+	-cd leveldb && $(MAKE) clean || true
 
 FORCE: