diff --git a/.gitignore b/.gitignore
index e5af811d1..d287d7e87 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,6 +6,7 @@ build_config.mk
 *.so.*
 *_test
 *.arc
+*.d
 db_bench
 db_stress
 ldb
diff --git a/Makefile b/Makefile
index f8f7e2810..13062d8e7 100644
--- a/Makefile
+++ b/Makefile
@@ -19,8 +19,8 @@ $(shell ./build_detect_platform build_config.mk)
 # this file is generated by the previous line to set build flags and sources
 include build_config.mk
 
-CFLAGS += -I. -I./include $(PLATFORM_CCFLAGS) $(OPT)
-CXXFLAGS += -I. -I./include $(PLATFORM_CXXFLAGS) $(OPT)
+CFLAGS += -Werror -I. -I./include $(PLATFORM_CCFLAGS) $(OPT)
+CXXFLAGS += -Werror -I. -I./include $(PLATFORM_CXXFLAGS) $(OPT)
 
 LDFLAGS += $(PLATFORM_LDFLAGS)
 
@@ -105,7 +105,7 @@ check: all $(PROGRAMS) $(TESTS) $(TOOLS)
 	for t in $(TESTS); do echo "***** Running $$t"; ./$$t || exit 1; done
 
 clean:
-	-rm -f $(PROGRAMS) $(BENCHMARKS) $(LIBRARY) $(SHARED) $(MEMENVLIBRARY) $(THRIFTSERVER) */*.o */*/*.o ios-x86/*/*.o ios-arm/*/*.o build_config.mk $(VERSIONFILE)
+	-rm -f $(PROGRAMS) $(BENCHMARKS) $(LIBRARY) $(SHARED) $(MEMENVLIBRARY) $(THRIFTSERVER) */*.o */*/*.o ios-x86/*/*.o ios-arm/*/*.o build_config.mk $(VERSIONFILE) */*.d
 	-rm -rf ios-x86/* ios-arm/*
 
 $(LIBRARY): $(LIBOBJECTS)
@@ -123,103 +123,95 @@ db_repl_stress: tools/db_repl_stress.o $(LIBOBJECTS) $(TESTUTIL)
 	$(CXX) tools/db_repl_stress.o $(LIBOBJECTS) $(TESTUTIL) $(EXEC_LDFLAGS) -o $@  $(LDFLAGS)
 
 db_bench_sqlite3: doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL)
-	$(CXX) doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL) -o $@ $(LDFLAGS) -lsqlite3
+	$(CXX) doc/bench/db_bench_sqlite3.o $(LIBOBJECTS) $(TESTUTIL) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS) -lsqlite3
 
 db_bench_tree_db: doc/bench/db_bench_tree_db.o $(LIBOBJECTS) $(TESTUTIL)
-	$(CXX) doc/bench/db_bench_tree_db.o $(LIBOBJECTS) $(TESTUTIL) -o $@ $(LDFLAGS) -lkyotocabinet
+	$(CXX) doc/bench/db_bench_tree_db.o $(LIBOBJECTS) $(TESTUTIL) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS) -lkyotocabinet
 
 arena_test: util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/arena_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 bloom_test: util/bloom_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/bloom_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/bloom_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 c_test: db/c_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/c_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 cache_test: util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/cache_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 coding_test: util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 corruption_test: db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/corruption_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 crc32c_test: util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/crc32c_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 db_test: db/db_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/db_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/db_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 dbformat_test: db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/dbformat_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 env_test: util/env_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/env_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/env_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 filename_test: db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/filename_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 filter_block_test: table/filter_block_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) table/filter_block_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) table/filter_block_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 log_test: db/log_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/log_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 table_test: table/table_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) table/table_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 block_test: table/block_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) table/block_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) table/block_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 skiplist_test: db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/skiplist_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 version_edit_test: db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/version_edit_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 version_set_test: db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/version_set_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 reduce_levels_test: tools/reduce_levels_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) tools/reduce_levels_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) tools/reduce_levels_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 write_batch_test: db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) db/write_batch_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 $(MEMENVLIBRARY) : $(MEMENVOBJECTS)
 	rm -f $@
 	$(AR) -rs $@ $(MEMENVOBJECTS)
 
 memenv_test : helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS)
-	$(CXX) helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) helpers/memenv/memenv_test.o $(MEMENVLIBRARY) $(LIBRARY) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 leveldb_shell: tools/shell/ShellContext.o tools/shell/ShellState.o tools/shell/LeveldbShell.o tools/shell/DBClientProxy.o tools/shell/ShellContext.h tools/shell/ShellState.h tools/shell/DBClientProxy.h $(LIBOBJECTS)
-	$(CXX) tools/shell/ShellContext.o tools/shell/ShellState.o tools/shell/LeveldbShell.o tools/shell/DBClientProxy.o $(LIBOBJECTS) -o $@ $(LDFLAGS)
+	$(CXX) tools/shell/ShellContext.o tools/shell/ShellState.o tools/shell/LeveldbShell.o tools/shell/DBClientProxy.o $(LIBOBJECTS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 DBClientProxy_test: tools/shell/test/DBClientProxyTest.o tools/shell/DBClientProxy.o $(LIBRARY) 
-	$(CXX) tools/shell/test/DBClientProxyTest.o tools/shell/DBClientProxy.o $(LIBRARY) $(EXEC_LDFLAGS) -o $@  $(LDFLAGS)
+	$(CXX) tools/shell/test/DBClientProxyTest.o tools/shell/DBClientProxy.o $(LIBRARY) $(EXEC_LDFLAGS) $(EXEC_LDFLAGS) -o$@  $(LDFLAGS)
 
 manifest_dump: tools/manifest_dump.o $(LIBOBJECTS)
-	$(CXX) tools/manifest_dump.o $(LIBOBJECTS) -o $@ $(LDFLAGS)
+	$(CXX) tools/manifest_dump.o $(LIBOBJECTS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 filelock_test: util/filelock_test.o $(LIBOBJECTS) $(TESTHARNESS)
-	$(CXX) util/filelock_test.o $(LIBOBJECTS) $(TESTHARNESS) -o $@ $(LDFLAGS)
+	$(CXX) util/filelock_test.o $(LIBOBJECTS) $(TESTHARNESS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 sst_dump: tools/sst_dump.o $(LIBOBJECTS)
-	$(CXX) tools/sst_dump.o $(LIBOBJECTS) -o $@ $(LDFLAGS)
+	$(CXX) tools/sst_dump.o $(LIBOBJECTS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 ldb: tools/ldb.o $(LIBOBJECTS)
-	$(CXX) tools/ldb.o $(LIBOBJECTS) -o $@ $(LDFLAGS)
-
-# recreate the version file with the latest git revision
-$(VERSIONFILE):	build_detect_version
-	$(shell ./build_detect_platform build_config.mk)
-
-# recreate the version file with the latest git revision
-$(VERSIONFILE):	build_detect_version
-	$(shell ./build_detect_platform build_config.mk)
+	$(CXX) tools/ldb.o $(LIBOBJECTS) $(EXEC_LDFLAGS) -o$@ $(LDFLAGS)
 
 ifeq ($(PLATFORM), IOS)
 # For iOS, create universal object files to be used on both the simulator and
@@ -250,3 +242,18 @@ else
 .c.o:
 	$(CC) $(CFLAGS) $(PLATFORM_SHARED_CFLAGS) -c $< -o $@
 endif
+
+%.d: %.cc
+	$(CXX) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) -MM $< -o $*.d
+	@cp -f $*.d $*.d.tmp
+	@sed -e 's|.*:|$*.o:|' < $*.d.tmp > $*.d
+	@rm -f $*.d.tmp
+
+DEPFILES = $(filter-out util/build_version.d,$(SOURCES:.cc=.d))
+
+depend: $(DEPFILES)
+
+ifneq ($(MAKECMDGOALS),clean)
+-include $(DEPFILES)
+endif
+
diff --git a/build_detect_platform b/build_detect_platform
index dc32c2c44..91ba87aa2 100755
--- a/build_detect_platform
+++ b/build_detect_platform
@@ -28,6 +28,11 @@ if test -z "$OUTPUT"; then
   exit 1
 fi
 
+# Default to fbcode gcc on internal fb machines
+if [ -d /mnt/gvfs/third-party -a -z "$CXX" ]; then
+    source fbcode.gcc471.sh
+fi
+
 # Delete existing output, if it exists
 rm -f $OUTPUT
 touch $OUTPUT
@@ -45,13 +50,13 @@ if test -z "$TARGET_OS"; then
     TARGET_OS=`uname -s`
 fi
 
-COMMON_FLAGS=
+COMMON_FLAGS="${CFLAGS}"
 CROSS_COMPILE=
 PLATFORM_CCFLAGS=
 PLATFORM_CXXFLAGS=
 PLATFORM_LDFLAGS=
 PLATFORM_SHARED_EXT="so"
-PLATFORM_SHARED_LDFLAGS="-shared -Wl,-soname -Wl,"
+PLATFORM_SHARED_LDFLAGS="${EXEC_LDFLAGS_SHARED} -shared -Wl,-soname -Wl,"
 PLATFORM_SHARED_CFLAGS="-fPIC"
 PLATFORM_SHARED_VERSIONED=true
 
@@ -59,51 +64,51 @@ PLATFORM_SHARED_VERSIONED=true
 case "$TARGET_OS" in
     Darwin)
         PLATFORM=OS_MACOSX
-        COMMON_FLAGS="-fno-builtin-memcmp -DOS_MACOSX"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -DOS_MACOSX"
         PLATFORM_SHARED_EXT=dylib
         PLATFORM_SHARED_LDFLAGS="-dynamiclib -install_name "
         PORT_FILE=port/port_posix.cc
         ;;
     Linux)
         PLATFORM=OS_LINUX
-        COMMON_FLAGS="-I/usr/include -fno-builtin-memcmp -pthread -DOS_LINUX -fPIC"
-        PLATFORM_LDFLAGS="-pthread"
+        COMMON_FLAGS="$COMMON_FLAGS -I/usr/include -fno-builtin-memcmp -pthread -DOS_LINUX -fPIC"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -pthread"
         PORT_FILE=port/port_posix.cc
         ;;
     SunOS)
         PLATFORM=OS_SOLARIS
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_SOLARIS"
-        PLATFORM_LDFLAGS="-lpthread -lrt"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_SOLARIS"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread -lrt"
         PORT_FILE=port/port_posix.cc
         ;;
     FreeBSD)
         PLATFORM=OS_FREEBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_FREEBSD"
-        PLATFORM_LDFLAGS="-lpthread"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_FREEBSD"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread"
         PORT_FILE=port/port_posix.cc
         ;;
     NetBSD)
         PLATFORM=OS_NETBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_NETBSD"
-        PLATFORM_LDFLAGS="-lpthread -lgcc_s"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_NETBSD"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread -lgcc_s"
         PORT_FILE=port/port_posix.cc
         ;;
     OpenBSD)
         PLATFORM=OS_OPENBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_OPENBSD"
-        PLATFORM_LDFLAGS="-pthread"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_OPENBSD"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -pthread"
         PORT_FILE=port/port_posix.cc
         ;;
     DragonFly)
         PLATFORM=OS_DRAGONFLYBSD
-        COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_DRAGONFLYBSD"
-        PLATFORM_LDFLAGS="-lpthread"
+        COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_DRAGONFLYBSD"
+        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread"
         PORT_FILE=port/port_posix.cc
         ;;
     OS_ANDROID_CROSSCOMPILE)
         PLATFORM=OS_ANDROID
-	COMMON_FLAGS="-fno-builtin-memcmp -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
-	PLATFORM_LDFLAGS=""  # All pthread features are in the Android C library
+	COMMON_FLAGS="$COMMON_FLAGS -fno-builtin-memcmp -D_REENTRANT -DOS_ANDROID -DLEVELDB_PLATFORM_POSIX"
+	PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS "  # All pthread features are in the Android C library
         PORT_FILE=port/port_posix.cc
         CROSS_COMPILE=true
         ;;
@@ -237,3 +242,4 @@ echo "PLATFORM_SHARED_EXT=$PLATFORM_SHARED_EXT" >> $OUTPUT
 echo "PLATFORM_SHARED_LDFLAGS=$PLATFORM_SHARED_LDFLAGS" >> $OUTPUT
 echo "PLATFORM_SHARED_VERSIONED=$PLATFORM_SHARED_VERSIONED" >> $OUTPUT
 echo "THRIFTSERVER=$THRIFTSERVER" >> $OUTPUT
+echo "EXEC_LDFLAGS=$EXEC_LDFLAGS" >> $OUTPUT
diff --git a/build_detect_version b/build_detect_version
index 79af43c95..db2fca8ef 100755
--- a/build_detect_version
+++ b/build_detect_version
@@ -14,7 +14,7 @@ VFILE=util/build_version.cc
 which git > /dev/null
 
 if [ "$?" = 0 ]; then
-  git rev-parse HEAD | awk ' BEGIN {print "#include \"build_version.h\""} {print "const char * leveldb_build_git_sha = \"leveldb_build_git_sha:" $0"\";"} END {}' >  ${VFILE}
+  env -i git rev-parse HEAD | awk ' BEGIN {print "#include \"build_version.h\""} {print "const char * leveldb_build_git_sha = \"leveldb_build_git_sha:" $0"\";"} END {}' >  ${VFILE}
 else
   echo "git not found"| awk ' BEGIN {print "#include \"build_version.h\""} {print "const char * leveldb_build_git_sha = \"leveldb_build_git_sha:git not found\";"} END {}' > ${VFILE}
 fi
diff --git a/db/db_impl.cc b/db/db_impl.cc
index 304dbc2a1..e7e105b62 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -1501,8 +1501,7 @@ Status DBImpl::InstallCompactionResults(CompactionState* compact) {
 // snapshots are typically small.
 inline SequenceNumber DBImpl::findEarliestVisibleSnapshot(
   SequenceNumber in, std::vector<SequenceNumber>& snapshots) {
-  SequenceNumber prev;
-  prev = 0;
+  SequenceNumber prev __attribute__((unused)) = 0;
   for (std::vector<SequenceNumber>::iterator it = snapshots.begin();
        it < snapshots.end(); it++) {
     assert (prev <= *it);
@@ -1564,7 +1563,8 @@ Status DBImpl::DoCompactionWork(CompactionState* compact) {
   ParsedInternalKey ikey;
   std::string current_user_key;
   bool has_current_user_key = false;
-  SequenceNumber last_sequence_for_key = kMaxSequenceNumber;
+  SequenceNumber last_sequence_for_key __attribute__((unused)) =
+    kMaxSequenceNumber;
   SequenceNumber visible_in_snapshot = kMaxSequenceNumber;
   for (; input->Valid() && !shutting_down_.Acquire_Load(); ) {
     // Prioritize immutable compaction work
diff --git a/db/snapshot.h b/db/snapshot.h
index dc7db09a2..1b9a57847 100644
--- a/db/snapshot.h
+++ b/db/snapshot.h
@@ -60,9 +60,8 @@ class SnapshotList {
   // retrieve all snapshot numbers. They are sorted in ascending order.
   void getAll(std::vector<SequenceNumber>& ret) {
     SnapshotImpl* s = &list_;
-    SequenceNumber prev;
-    prev = 0;
     if (empty()) return;
+    SequenceNumber prev __attribute__((unused)) = 0;
     while (s->next_ != &list_) {
       assert(prev <= s->next_->number_);
       assert(prev = s->next_->number_); // assignment
diff --git a/db/version_set.cc b/db/version_set.cc
index 7310a72cb..eb45fdc95 100644
--- a/db/version_set.cc
+++ b/db/version_set.cc
@@ -592,6 +592,7 @@ void Version::ExtendOverlappingInputs(
 #endif
   int startIndex = midIndex + 1;
   int endIndex = midIndex;
+  int count __attribute__((unused)) = 0;
 
   // check backwards from 'mid' to lower indices
   for (int i = midIndex; i >= 0 ; i--) {
diff --git a/fbcode.gcc471.sh b/fbcode.gcc471.sh
index 50e742aa2..83f8bf245 100644
--- a/fbcode.gcc471.sh
+++ b/fbcode.gcc471.sh
@@ -47,7 +47,8 @@ CFLAGS+=" -I $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/include -DHAVE_JEMALLOC
 EXEC_LDFLAGS=" -Wl,--whole-archive $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.a"
 EXEC_LDFLAGS+=" -Wl,--no-whole-archive $TOOLCHAIN_LIB_BASE/libunwind/libunwind-20100812_experimental/91ddd43/lib/libunwind.a"
 EXEC_LDFLAGS+=" $HDFSLIB $SNAPPY_LIBS $THRIFT_LIBS $LIBEVENT_LIBS"
-EXEC_LDFLAGS_SHARED="$SNAPPY_LIBS $TOOLCHAIN_LIB_BASE/jemalloc/$TOOL_JEMALLOC/lib/libjemalloc.so"
+
+EXEC_LDFLAGS_SHARED="$SNAPPY_LIBS"
 SNAPPY_LDFLAGS="$SNAPPY_LIBS"
 
 export CC CXX AR RANLIB CFLAGS EXEC_LDFLAGS EXEC_LDFLAGS_SHARED SNAPPY_LDFLAGS
diff --git a/include/leveldb/c.h b/include/leveldb/c.h
index 70e3cc652..f62ffc07b 100644
--- a/include/leveldb/c.h
+++ b/include/leveldb/c.h
@@ -199,6 +199,8 @@ extern void leveldb_options_set_max_open_files(leveldb_options_t*, int);
 extern void leveldb_options_set_cache(leveldb_options_t*, leveldb_cache_t*);
 extern void leveldb_options_set_block_size(leveldb_options_t*, size_t);
 extern void leveldb_options_set_block_restart_interval(leveldb_options_t*, int);
+extern void leveldb_options_set_compression_options(
+    leveldb_options_t* opt, int w_bits, int level, int strategy);
 
 enum {
   leveldb_no_compression = 0,