diff --git a/adb/Android.mk b/adb/Android.mk
index 41016ee..bbdc2ea 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -5,12 +5,6 @@
 
 LOCAL_PATH:= $(call my-dir)
 
-ifeq ($(HOST_OS),windows)
-    adb_host_clang := false  # libc++ for mingw not ready yet.
-else
-    adb_host_clang := true
-endif
-
 adb_host_sanitize :=
 adb_target_sanitize :=
 
@@ -29,8 +23,6 @@
 ADB_COMMON_windows_CFLAGS := \
     -DUNICODE=1 -D_UNICODE=1 \
 
-ADB_COMMON_CFLAGS += $(ADB_COMMON_$(HOST_OS)_CFLAGS)
-
 # libadb
 # =========================================================
 
@@ -63,7 +55,8 @@
 LIBADB_linux_CFLAGS := \
     -std=c++14 \
 
-LIBADB_CFLAGS += $(LIBADB_$(HOST_OS)_CFLAGS)
+LIBADB_windows_CFLAGS := \
+    $(ADB_COMMON_windows_CFLAGS) \
 
 LIBADB_darwin_SRC_FILES := \
     fdevent.cpp \
@@ -97,7 +90,6 @@
     usb_linux_client.cpp \
 
 LOCAL_SANITIZE := $(adb_target_sanitize)
-LOCAL_SHARED_LIBRARIES := libbase
 
 # Even though we're building a static library (and thus there's no link step for
 # this to take effect), this adds the includes to our path.
@@ -106,24 +98,27 @@
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
-LOCAL_CLANG := $(adb_host_clang)
 LOCAL_MODULE := libadb
+LOCAL_MODULE_HOST_OS := darwin linux windows
 LOCAL_CFLAGS := $(LIBADB_CFLAGS) -DADB_HOST=1
+LOCAL_CFLAGS_windows := $(LIBADB_windows_CFLAGS)
+LOCAL_CFLAGS_linux := $(LIBADB_linux_CFLAGS)
 LOCAL_SRC_FILES := \
     $(LIBADB_SRC_FILES) \
-    $(LIBADB_$(HOST_OS)_SRC_FILES) \
     adb_auth_host.cpp \
 
+LOCAL_SRC_FILES_darwin := $(LIBADB_darwin_SRC_FILES)
+LOCAL_SRC_FILES_linux := $(LIBADB_linux_SRC_FILES)
+LOCAL_SRC_FILES_windows := $(LIBADB_windows_SRC_FILES)
+
 LOCAL_SANITIZE := $(adb_host_sanitize)
-LOCAL_SHARED_LIBRARIES := libbase
 
 # Even though we're building a static library (and thus there's no link step for
 # this to take effect), this adds the includes to our path.
 LOCAL_STATIC_LIBRARIES := libcrypto_static libbase
 
-ifeq ($(HOST_OS),windows)
-    LOCAL_C_INCLUDES += development/host/windows/usb/api/
-else
+LOCAL_C_INCLUDES_windows := development/host/windows/usb/api/
+ifneq ($(HOST_OS),windows)
     LOCAL_MULTILIB := 64
 endif
 
@@ -146,14 +141,13 @@
 # =========================================================
 
 include $(CLEAR_VARS)
-LOCAL_CLANG := $(adb_host_clang)
 LOCAL_MODULE := adb_test
 LOCAL_CFLAGS := -DADB_HOST=1 $(LIBADB_CFLAGS)
-LOCAL_SRC_FILES := \
-    $(LIBADB_TEST_SRCS) \
-    $(LIBADB_TEST_$(HOST_OS)_SRCS) \
-    services.cpp \
-
+LOCAL_CFLAGS_windows := $(LIBADB_windows_CFLAGS)
+LOCAL_CFLAGS_linux := $(LIBADB_linux_CFLAGS)
+LOCAL_SRC_FILES := $(LIBADB_TEST_SRCS) services.cpp
+LOCAL_SRC_FILES_linux := $(LIBADB_TEST_linux_SRCS)
+LOCAL_SRC_FILES_darwin := $(LIBADB_TEST_darwin_SRCS)
 LOCAL_SANITIZE := $(adb_host_sanitize)
 LOCAL_SHARED_LIBRARIES := liblog libbase
 LOCAL_STATIC_LIBRARIES := \
@@ -161,18 +155,10 @@
     libcrypto_static \
     libcutils \
 
-ifeq ($(HOST_OS),linux)
-    LOCAL_LDLIBS += -lrt -ldl -lpthread
-endif
-
-ifeq ($(HOST_OS),darwin)
-    LOCAL_LDLIBS += -framework CoreFoundation -framework IOKit
-endif
-
-ifeq ($(HOST_OS),windows)
-    LOCAL_LDLIBS += -lws2_32 -luserenv
-    LOCAL_STATIC_LIBRARIES += AdbWinApi
-endif
+LOCAL_LDLIBS_linux := -lrt -ldl -lpthread
+LOCAL_LDLIBS_darwin := -framework CoreFoundation -framework IOKit
+LOCAL_LDLIBS_windows := -lws2_32 -luserenv
+LOCAL_STATIC_LIBRARIES_windows := AdbWinApi
 
 include $(BUILD_HOST_NATIVE_TEST)
 
@@ -181,9 +167,10 @@
 
 ifeq ($(HOST_OS),linux)
 include $(CLEAR_VARS)
-LOCAL_CLANG := $(adb_host_clang)
 LOCAL_MODULE := adb_device_tracker_test
 LOCAL_CFLAGS := -DADB_HOST=1 $(LIBADB_CFLAGS)
+LOCAL_CFLAGS_windows := $(LIBADB_windows_CFLAGS)
+LOCAL_CFLAGS_linux := $(LIBADB_linux_CFLAGS)
 LOCAL_SRC_FILES := test_track_devices.cpp
 LOCAL_SANITIZE := $(adb_host_sanitize)
 LOCAL_SHARED_LIBRARIES := liblog libbase
@@ -196,23 +183,16 @@
 # =========================================================
 include $(CLEAR_VARS)
 
-ifeq ($(HOST_OS),linux)
-    LOCAL_LDLIBS += -lrt -ldl -lpthread
-endif
+LOCAL_LDLIBS_linux := -lrt -ldl -lpthread
 
-ifeq ($(HOST_OS),darwin)
-    LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
-    LOCAL_CFLAGS += -Wno-sizeof-pointer-memaccess -Wno-unused-parameter
-endif
+LOCAL_LDLIBS_darwin := -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
+LOCAL_CFLAGS_darwin := -Wno-sizeof-pointer-memaccess -Wno-unused-parameter
 
-ifeq ($(HOST_OS),windows)
-    # Use wmain instead of main
-    LOCAL_LDFLAGS += -municode
-    LOCAL_LDLIBS += -lws2_32 -lgdi32
-    EXTRA_STATIC_LIBS := AdbWinApi
-endif
-
-LOCAL_CLANG := $(adb_host_clang)
+# Use wmain instead of main
+LOCAL_LDFLAGS_windows := -municode
+LOCAL_LDLIBS_windows := -lws2_32 -lgdi32
+LOCAL_STATIC_LIBRARIES_windows := AdbWinApi
+LOCAL_REQUIRED_MODULES_windows := AdbWinApi AdbWinUsbApi
 
 LOCAL_SRC_FILES := \
     client/main.cpp \
@@ -227,8 +207,12 @@
     -D_GNU_SOURCE \
     -DADB_HOST=1 \
 
+LOCAL_CFLAGS_windows := \
+    $(ADB_COMMON_windows_CFLAGS)
+
 LOCAL_MODULE := adb
 LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_HOST_OS := darwin linux windows
 
 LOCAL_SANITIZE := $(adb_host_sanitize)
 LOCAL_STATIC_LIBRARIES := \
@@ -237,12 +221,8 @@
     libcrypto_static \
     libcutils \
     liblog \
-    $(EXTRA_STATIC_LIBS) \
 
-# libc++ not available on windows yet
-ifneq ($(HOST_OS),windows)
-    LOCAL_CXX_STL := libc++_static
-endif
+LOCAL_CXX_STL := libc++_static
 
 # Don't add anything here, we don't want additional shared dependencies
 # on the host adb tool, and shared libraries that link against libc++
@@ -253,12 +233,6 @@
 
 $(call dist-for-goals,dist_files sdk,$(LOCAL_BUILT_MODULE))
 
-ifeq ($(HOST_OS),windows)
-$(LOCAL_INSTALLED_MODULE): \
-    $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll \
-    $(HOST_OUT_EXECUTABLES)/AdbWinUsbApi.dll
-endif
-
 
 # adbd device daemon
 # =========================================================
diff --git a/base/Android.mk b/base/Android.mk
index 4e135f6..51dd736 100644
--- a/base/Android.mk
+++ b/base/Android.mk
@@ -68,6 +68,7 @@
 LOCAL_EXPORT_C_INCLUDE_DIRS := $(LOCAL_PATH)/include
 LOCAL_STATIC_LIBRARIES := libcutils
 LOCAL_MULTILIB := both
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
diff --git a/fastboot/Android.mk b/fastboot/Android.mk
index ce8e15f..3f201ec 100644
--- a/fastboot/Android.mk
+++ b/fastboot/Android.mk
@@ -24,38 +24,25 @@
 LOCAL_SRC_FILES := protocol.cpp engine.cpp bootimg_utils.cpp fastboot.cpp util.cpp fs.cpp
 LOCAL_MODULE := fastboot
 LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_HOST_OS := darwin linux windows
 LOCAL_CONLYFLAGS += -std=gnu99
 LOCAL_CFLAGS += -Wall -Wextra -Werror -Wunreachable-code
 
 LOCAL_CFLAGS += -DFASTBOOT_REVISION='"$(fastboot_version)"'
 
-ifeq ($(HOST_OS),linux)
-  LOCAL_SRC_FILES += usb_linux.cpp util_linux.cpp
-endif
+LOCAL_SRC_FILES_linux := usb_linux.cpp util_linux.cpp
 
-ifeq ($(HOST_OS),darwin)
-  LOCAL_SRC_FILES += usb_osx.cpp util_osx.cpp
-  LOCAL_LDLIBS += -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
-  LOCAL_CFLAGS += -Wno-unused-parameter
-endif
+LOCAL_SRC_FILES_darwin := usb_osx.cpp util_osx.cpp
+LOCAL_LDLIBS_darwin := -lpthread -framework CoreFoundation -framework IOKit -framework Carbon
+LOCAL_CFLAGS_darwin := -Wno-unused-parameter
 
-ifeq ($(HOST_OS),windows)
-  LOCAL_SRC_FILES += usb_windows.cpp util_windows.cpp
-  EXTRA_STATIC_LIBS := AdbWinApi
-  ifneq ($(strip $(USE_CYGWIN)),)
-    # Pure cygwin case
-    LOCAL_LDLIBS += -lpthread
-  endif
-  ifneq ($(strip $(USE_MINGW)),)
-    # MinGW under Linux case
-    LOCAL_LDLIBS += -lws2_32
-    USE_SYSDEPS_WIN32 := 1
-  endif
-  LOCAL_C_INCLUDES += development/host/windows/usb/api
-endif
+LOCAL_SRC_FILES_windows := usb_windows.cpp util_windows.cpp
+LOCAL_STATIC_LIBRARIES_windows := AdbWinApi
+LOCAL_REQUIRED_MODULES_windows := AdbWinApi
+LOCAL_LDLIBS_windows := -lws2_32
+LOCAL_C_INCLUDES_windows := development/host/windows/usb/api
 
 LOCAL_STATIC_LIBRARIES := \
-    $(EXTRA_STATIC_LIBS) \
     libziparchive-host \
     libext4_utils_host \
     libsparse_host \
@@ -64,24 +51,18 @@
     libz \
     libbase
 
-ifneq ($(HOST_OS),windows)
-LOCAL_STATIC_LIBRARIES += libselinux
-endif # HOST_OS != windows
+LOCAL_STATIC_LIBRARIES_darwin := libselinux
+LOCAL_STATIC_LIBRARIES_linux := libselinux
 
-ifeq ($(HOST_OS),linux)
 # libf2fs_dlutils_host will dlopen("libf2fs_fmt_host_dyn")
-LOCAL_CFLAGS += -DUSE_F2FS
-LOCAL_LDFLAGS += -ldl -rdynamic -Wl,-rpath,.
-LOCAL_REQUIRED_MODULES := libf2fs_fmt_host_dyn
+LOCAL_CFLAGS_linux := -DUSE_F2FS
+LOCAL_LDFLAGS_linux := -ldl -rdynamic -Wl,-rpath,.
+LOCAL_REQUIRED_MODULES_linux := libf2fs_fmt_host_dyn
 # The following libf2fs_* are from system/extras/f2fs_utils,
 # and do not use code in external/f2fs-tools.
-LOCAL_STATIC_LIBRARIES += libf2fs_utils_host libf2fs_ioutils_host libf2fs_dlutils_host
-endif
+LOCAL_STATIC_LIBRARIES_linux += libf2fs_utils_host libf2fs_ioutils_host libf2fs_dlutils_host
 
-# libc++ not available on windows yet
-ifneq ($(HOST_OS),windows)
-    LOCAL_CXX_STL := libc++_static
-endif
+LOCAL_CXX_STL := libc++_static
 
 # Don't add anything here, we don't want additional shared dependencies
 # on the host fastboot tool, and shared libraries that link against libc++
@@ -104,7 +85,3 @@
 LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_EXECUTABLE)
 endif
-
-ifeq ($(HOST_OS),windows)
-$(LOCAL_INSTALLED_MODULE): $(HOST_OUT_EXECUTABLES)/AdbWinApi.dll
-endif
diff --git a/include/private/android_filesystem_config.h b/include/private/android_filesystem_config.h
index 7047e0f..3e8d62a 100644
--- a/include/private/android_filesystem_config.h
+++ b/include/private/android_filesystem_config.h
@@ -32,6 +32,8 @@
 #include "android_filesystem_capability.h"
 #endif
 
+#define CAP_MASK_LONG(cap_name)  (1ULL << (cap_name))
+
 /* This is the master Users and Groups config for the platform.
  * DO NOT EVER RENUMBER
  */
diff --git a/libcutils/Android.mk b/libcutils/Android.mk
index f9060c4..015bd3f 100644
--- a/libcutils/Android.mk
+++ b/libcutils/Android.mk
@@ -37,19 +37,7 @@
 # some files must not be compiled when building against Mingw
 # they correspond to features not used by our host development tools
 # which are also hard or even impossible to port to native Win32
-WINDOWS_HOST_ONLY :=
-ifeq ($(HOST_OS),windows)
-    ifeq ($(strip $(USE_CYGWIN)),)
-        WINDOWS_HOST_ONLY := 1
-    endif
-endif
-# USE_MINGW is defined when we build against Mingw on Linux
-ifneq ($(strip $(USE_MINGW)),)
-    WINDOWS_HOST_ONLY := 1
-endif
-
-ifneq ($(WINDOWS_HOST_ONLY),1)
-    commonSources += \
+nonWindowsSources := \
         fs.c \
         multiuser.c \
         socket_inaddr_any_server.c \
@@ -60,31 +48,32 @@
         socket_network_client.c \
         sockets.c \
 
-    commonHostSources += \
+nonWindowsHostSources := \
         ashmem-host.c \
         trace-host.c
 
-endif
-
 
 # Shared and static library for host
 # ========================================================
 LOCAL_MODULE := libcutils
-LOCAL_SRC_FILES := $(commonSources) $(commonHostSources) dlmalloc_stubs.c
+LOCAL_SRC_FILES := $(commonSources) dlmalloc_stubs.c
+LOCAL_SRC_FILES_darwin := $(nonWindowsSources) $(nonWindowsHostSources)
+LOCAL_SRC_FILES_linux := $(nonWindowsSources) $(nonWindowsHostSources)
 LOCAL_STATIC_LIBRARIES := liblog
-ifneq ($(HOST_OS),windows)
-LOCAL_CFLAGS += -Werror -Wall -Wextra
-endif
+LOCAL_CFLAGS_darwin := -Werror -Wall -Wextra
+LOCAL_CFLAGS_linux := -Werror -Wall -Wextra
 LOCAL_MULTILIB := both
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := libcutils
-LOCAL_SRC_FILES := $(commonSources) $(commonHostSources) dlmalloc_stubs.c
+LOCAL_SRC_FILES := $(commonSources) dlmalloc_stubs.c
+LOCAL_SRC_FILES_darwin := $(nonWindowsSources) $(nonWindowsHostSources)
+LOCAL_SRC_FILES_linux := $(nonWindowsSources) $(nonWindowsHostSources)
 LOCAL_SHARED_LIBRARIES := liblog
-ifneq ($(HOST_OS),windows)
-LOCAL_CFLAGS += -Werror -Wall -Wextra
-endif
+LOCAL_CFLAGS_darwin := -Werror -Wall -Wextra
+LOCAL_CFLAGS_linux := -Werror -Wall -Wextra
 LOCAL_MULTILIB := both
 include $(BUILD_HOST_SHARED_LIBRARY)
 
@@ -96,6 +85,7 @@
 include $(CLEAR_VARS)
 LOCAL_MODULE := libcutils
 LOCAL_SRC_FILES := $(commonSources) \
+        $(nonWindowsSources) \
         android_reboot.c \
         ashmem-dev.c \
         debugger.c \
diff --git a/libcutils/fs_config.c b/libcutils/fs_config.c
index 5f6f8f9..27981ff 100644
--- a/libcutils/fs_config.c
+++ b/libcutils/fs_config.c
@@ -135,8 +135,8 @@
     { 04770, AID_ROOT,      AID_RADIO,     0, "system/bin/pppd-ril" },
 
     /* the following files have enhanced capabilities and ARE included in user builds. */
-    { 00750, AID_ROOT,      AID_SHELL,     (1ULL << CAP_SETUID) | (1ULL << CAP_SETGID), "system/bin/run-as" },
-    { 00700, AID_SYSTEM,    AID_SHELL,     (1ULL << CAP_BLOCK_SUSPEND), "system/bin/inputflinger" },
+    { 00750, AID_ROOT,      AID_SHELL,     CAP_MASK_LONG(CAP_SETUID) | CAP_MASK_LONG(CAP_SETGID), "system/bin/run-as" },
+    { 00700, AID_SYSTEM,    AID_SHELL,     CAP_MASK_LONG(CAP_BLOCK_SUSPEND), "system/bin/inputflinger" },
 
     { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/uncrypt" },
     { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/install-recovery.sh" },
diff --git a/liblog/Android.mk b/liblog/Android.mk
index 5eed634..3a1a9db 100644
--- a/liblog/Android.mk
+++ b/liblog/Android.mk
@@ -24,41 +24,30 @@
 # so make sure we do not regret hard-coding it as follows:
 liblog_cflags := -DLIBLOG_LOG_TAG=1005
 
-liblog_sources := logd_write.c log_event_write.c
-
-# some files must not be compiled when building against Mingw
-# they correspond to features not used by our host development tools
-# which are also hard or even impossible to port to native Win32
-
-ifeq ($(strip $(USE_MINGW)),)
-    liblog_sources += \
-        event_tag_map.c
-else
-    liblog_sources += \
-        uio.c
-endif
-
-liblog_host_sources := $(liblog_sources) fake_log_device.c event.logtags
-liblog_target_sources := $(liblog_sources) log_time.cpp log_is_loggable.c
-ifeq ($(strip $(USE_MINGW)),)
+liblog_host_sources := logd_write.c log_event_write.c fake_log_device.c event.logtags
+liblog_target_sources := logd_write.c log_event_write.c event_tag_map.c log_time.cpp log_is_loggable.c
 liblog_target_sources += logprint.c
-endif
 liblog_target_sources += log_read.c
 
 # Shared and static library for host
 # ========================================================
 LOCAL_MODULE := liblog
 LOCAL_SRC_FILES := $(liblog_host_sources)
+# some files must not be compiled when building against Mingw
+# they correspond to features not used by our host development tools
+# which are also hard or even impossible to port to native Win32
+LOCAL_SRC_FILES_darwin := event_tag_map.c
+LOCAL_SRC_FILES_linux := event_tag_map.c
+LOCAL_SRC_FILES_windows := uio.c
 LOCAL_CFLAGS := -DFAKE_LOG_DEVICE=1 -Werror $(liblog_cflags)
 LOCAL_MULTILIB := both
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := liblog
 LOCAL_WHOLE_STATIC_LIBRARIES := liblog
-ifeq ($(strip $(HOST_OS)),linux)
-LOCAL_LDLIBS := -lrt
-endif
+LOCAL_LDLIBS_linux := -lrt
 LOCAL_MULTILIB := both
 LOCAL_CXX_STL := none
 include $(BUILD_HOST_SHARED_LIBRARY)
diff --git a/libsparse/Android.mk b/libsparse/Android.mk
index 925b98b..c77eba9 100644
--- a/libsparse/Android.mk
+++ b/libsparse/Android.mk
@@ -18,6 +18,7 @@
 LOCAL_STATIC_LIBRARIES := libz
 LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
 LOCAL_CFLAGS := -Werror
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 
diff --git a/libutils/Android.mk b/libutils/Android.mk
index 8226db2..1039096 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -43,27 +43,19 @@
 
 host_commonCflags := -DLIBUTILS_NATIVE=1 $(TOOL_CFLAGS) -Werror
 
-ifeq ($(HOST_OS),windows)
-ifeq ($(strip $(USE_CYGWIN),),)
-# Under MinGW, ctype.h doesn't need multi-byte support
-host_commonCflags += -DMB_CUR_MAX=1
-endif
-endif
-
 # For the host
 # =====================================================
 include $(CLEAR_VARS)
 LOCAL_SRC_FILES:= $(commonSources)
-ifeq ($(HOST_OS), linux)
-LOCAL_SRC_FILES += Looper.cpp
-endif
-ifeq ($(HOST_OS),darwin)
-LOCAL_CFLAGS += -Wno-unused-parameter
-endif
+LOCAL_SRC_FILES_linux := Looper.cpp
+LOCAL_CFLAGS_darwin := -Wno-unused-parameter
 LOCAL_MODULE:= libutils
 LOCAL_STATIC_LIBRARIES := liblog
 LOCAL_CFLAGS += $(host_commonCflags)
+# Under MinGW, ctype.h doesn't need multi-byte support
+LOCAL_CFLAGS_windows := -DMB_CUR_MAX=1
 LOCAL_MULTILIB := both
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 
diff --git a/libziparchive/Android.mk b/libziparchive/Android.mk
index 559c48b..608ff1c 100644
--- a/libziparchive/Android.mk
+++ b/libziparchive/Android.mk
@@ -33,10 +33,9 @@
 LOCAL_STATIC_LIBRARIES := libz libutils libbase
 LOCAL_MODULE:= libziparchive-host
 LOCAL_CFLAGS := -Werror
-ifneq ($(strip $(USE_MINGW)),)
-	LOCAL_CFLAGS += -mno-ms-bitfields
-endif
+LOCAL_CFLAGS_windows := -mno-ms-bitfields
 LOCAL_MULTILIB := both
+LOCAL_MODULE_HOST_OS := darwin linux windows
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
diff --git a/metricsd/Android.mk b/metricsd/Android.mk
index 12dfa18..d619b32 100644
--- a/metricsd/Android.mk
+++ b/metricsd/Android.mk
@@ -133,7 +133,9 @@
   libchromeos-http \
   libchromeos-dbus \
   libcutils \
-  libdbus
+  libdbus \
+  librootdev
+
 LOCAL_SRC_FILES := $(metrics_daemon_sources)
 LOCAL_STATIC_LIBRARIES := metrics_daemon_protos
 include $(BUILD_EXECUTABLE)
diff --git a/metricsd/metrics_daemon.cc b/metricsd/metrics_daemon.cc
index cf4d79d..c188aa4 100644
--- a/metricsd/metrics_daemon.cc
+++ b/metricsd/metrics_daemon.cc
@@ -84,8 +84,6 @@
 const int kMetricStatsShortInterval = 1;  // seconds
 const int kMetricStatsLongInterval = 30;  // seconds
 
-const int kMetricMeminfoInterval = 30;        // seconds
-
 // Assume a max rate of 250Mb/s for reads (worse for writes) and 512 byte
 // sectors.
 const int kMetricSectorsIOMax = 500000;  // sectors/second
@@ -112,6 +110,7 @@
 const char kVmStatFileName[] = "/proc/vmstat";
 const char kMeminfoFileName[] = "/proc/meminfo";
 const int kMetricsProcStatFirstLineItemsCount = 11;
+const int kDiskMetricsStatItemCount = 11;
 
 // Thermal CPU throttling.
 
@@ -217,6 +216,7 @@
                          bool uploader_active,
                          bool dbus_enabled,
                          MetricsLibraryInterface* metrics_lib,
+                         const string& diskstats_path,
                          const string& scaling_max_freq_path,
                          const string& cpuinfo_max_freq_path,
                          const base::TimeDelta& upload_interval,
@@ -275,8 +275,13 @@
   weekly_cycle_.reset(new PersistentInteger("weekly.cycle"));
   version_cycle_.reset(new PersistentInteger("version.cycle"));
 
+  diskstats_path_ = diskstats_path;
   scaling_max_freq_path_ = scaling_max_freq_path;
   cpuinfo_max_freq_path_ = cpuinfo_max_freq_path;
+
+  // If testing, initialize Stats Reporter without connecting DBus
+  if (testing_)
+    StatsReporterInit();
 }
 
 int MetricsDaemon::OnInit() {
@@ -285,6 +290,13 @@
   if (return_code != EX_OK)
     return return_code;
 
+  StatsReporterInit();
+
+  // Start collecting meminfo stats.
+  ScheduleMeminfoCallback(kMetricMeminfoInterval);
+  memuse_final_time_ = GetActiveTime() + kMemuseIntervals[0];
+  ScheduleMemuseCallback(kMemuseIntervals[0]);
+
   if (testing_)
     return EX_OK;
 
@@ -315,6 +327,11 @@
     }
   }
 
+  base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
+      base::Bind(&MetricsDaemon::HandleUpdateStatsTimeout,
+                 base::Unretained(this)),
+      base::TimeDelta::FromMilliseconds(kUpdateStatsIntervalMs));
+
   if (uploader_active_) {
     upload_service_.reset(
         new UploadService(new SystemProfileCache(), metrics_lib_, server_));
@@ -496,6 +513,40 @@
       base::TimeDelta::FromSeconds(wait));
 }
 
+bool MetricsDaemon::DiskStatsReadStats(uint64_t* read_sectors,
+                                       uint64_t* write_sectors) {
+  CHECK(read_sectors);
+  CHECK(write_sectors);
+  std::string line;
+  if (diskstats_path_.empty()) {
+    return false;
+  }
+
+  if (!base::ReadFileToString(base::FilePath(diskstats_path_), &line)) {
+    PLOG(WARNING) << "Could not read disk stats from " << diskstats_path_;
+    return false;
+  }
+
+  std::vector<std::string> parts = base::SplitString(
+      line, " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_NONEMPTY);
+  if (parts.size() != kDiskMetricsStatItemCount) {
+    LOG(ERROR) << "Could not parse disk stat correctly. Expected "
+               << kDiskMetricsStatItemCount << " elements but got "
+               << parts.size();
+    return false;
+  }
+  if (!base::StringToUint64(parts[2], read_sectors)) {
+    LOG(ERROR) << "Couldn't convert read sectors " << parts[2] << " to uint64";
+    return false;
+  }
+  if (!base::StringToUint64(parts[6], write_sectors)) {
+    LOG(ERROR) << "Couldn't convert write sectors " << parts[6] << " to uint64";
+    return false;
+  }
+
+  return true;
+}
+
 bool MetricsDaemon::VmStatsParseStats(const char* stats,
                                       struct VmstatRecord* record) {
   CHECK(stats);
@@ -715,10 +766,7 @@
   }
   // Make both calls even if the first one fails.
   bool success = ProcessMeminfo(meminfo_raw);
-  bool reschedule =
-      ReportZram(base::FilePath(FILE_PATH_LITERAL("/sys/block/zram0"))) &&
-      success;
-  if (reschedule) {
+  if (ProcessMeminfo(meminfo_raw)) {
     base::MessageLoop::current()->PostDelayedTask(FROM_HERE,
         base::Bind(&MetricsDaemon::MeminfoCallback, base::Unretained(this),
                    wait),
diff --git a/metricsd/metrics_daemon.h b/metricsd/metrics_daemon.h
index 9180e23..7f7ea63 100644
--- a/metricsd/metrics_daemon.h
+++ b/metricsd/metrics_daemon.h
@@ -45,6 +45,7 @@
             bool uploader_active,
             bool dbus_enabled,
             MetricsLibraryInterface* metrics_lib,
+            const std::string& diskstats_path,
             const std::string& cpuinfo_max_freq_path,
             const std::string& scaling_max_freq_path,
             const base::TimeDelta& upload_interval,
@@ -78,6 +79,7 @@
   FRIEND_TEST(MetricsDaemonTest, GetHistogramPath);
   FRIEND_TEST(MetricsDaemonTest, IsNewEpoch);
   FRIEND_TEST(MetricsDaemonTest, MessageFilter);
+  FRIEND_TEST(MetricsDaemonTest, ParseDiskStats);
   FRIEND_TEST(MetricsDaemonTest, ParseVmStats);
   FRIEND_TEST(MetricsDaemonTest, ProcessKernelCrash);
   FRIEND_TEST(MetricsDaemonTest, ProcessMeminfo);
@@ -86,7 +88,6 @@
   FRIEND_TEST(MetricsDaemonTest, ProcessUserCrash);
   FRIEND_TEST(MetricsDaemonTest, ReportCrashesDailyFrequency);
   FRIEND_TEST(MetricsDaemonTest, ReadFreqToInt);
-  FRIEND_TEST(MetricsDaemonTest, ReportDiskStats);
   FRIEND_TEST(MetricsDaemonTest, ReportKernelCrashInterval);
   FRIEND_TEST(MetricsDaemonTest, ReportUncleanShutdownInterval);
   FRIEND_TEST(MetricsDaemonTest, ReportUserCrashInterval);
@@ -324,6 +325,7 @@
   scoped_ptr<PersistentInteger> unclean_shutdowns_daily_count_;
   scoped_ptr<PersistentInteger> unclean_shutdowns_weekly_count_;
 
+  std::string diskstats_path_;
   std::string scaling_max_freq_path_;
   std::string cpuinfo_max_freq_path_;
 
diff --git a/metricsd/metrics_daemon_main.cc b/metricsd/metrics_daemon_main.cc
index 7f9ec43..43046f8 100644
--- a/metricsd/metrics_daemon_main.cc
+++ b/metricsd/metrics_daemon_main.cc
@@ -20,6 +20,7 @@
 #include <base/strings/string_util.h>
 #include <chromeos/flag_helper.h>
 #include <chromeos/syslog_logging.h>
+#include <rootdev.h>
 
 #include "constants.h"
 #include "metrics_daemon.h"
@@ -29,6 +30,28 @@
 const char kCpuinfoMaxFreqPath[] =
     "/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq";
 
+// Returns the path to the disk stats in the sysfs.  Returns the null string if
+// it cannot find the disk stats file.
+static
+const std::string MetricsMainDiskStatsPath() {
+  char dev_path_cstr[PATH_MAX];
+  std::string dev_prefix = "/dev/block/";
+  std::string dev_path;
+
+  int ret = rootdev(dev_path_cstr, sizeof(dev_path_cstr), true, true);
+  if (ret != 0) {
+    LOG(WARNING) << "error " << ret << " determining root device";
+    return "";
+  }
+  dev_path = dev_path_cstr;
+  // Check that rootdev begins with "/dev/block/".
+  if (!base::StartsWithASCII(dev_path, dev_prefix, false)) {
+    LOG(WARNING) << "unexpected root device " << dev_path;
+    return "";
+  }
+  return "/sys/class/block/" + dev_path.substr(dev_prefix.length()) + "/stat";
+}
+
 int main(int argc, char** argv) {
   DEFINE_bool(daemon, true, "run as daemon (use -nodaemon for debugging)");
 
@@ -75,6 +98,7 @@
               FLAGS_uploader | FLAGS_uploader_test,
               FLAGS_withdbus,
               &metrics_lib,
+              MetricsMainDiskStatsPath(),
               kScalingMaxFreqPath,
               kCpuinfoMaxFreqPath,
               base::TimeDelta::FromSeconds(FLAGS_upload_interval_secs),
diff --git a/metricsd/metrics_daemon_test.cc b/metricsd/metrics_daemon_test.cc
index 0d2229c..4ef097e 100644
--- a/metricsd/metrics_daemon_test.cc
+++ b/metricsd/metrics_daemon_test.cc
@@ -82,6 +82,7 @@
                  false,
                  true,
                  &metrics_lib_,
+                 disk_stats_path_.value(),
                  scaling_max_freq_path_.value(),
                  cpu_max_freq_path_.value(),
                  base::TimeDelta::FromMinutes(30),
@@ -198,6 +199,21 @@
                      /* min */ 1, /* max */ 100, /* buckets */ 50);
 }
 
+TEST_F(MetricsDaemonTest, ParseDiskStats) {
+  uint64_t read_sectors_now, write_sectors_now;
+  CreateFakeDiskStatsFile(kFakeDiskStats0);
+  ASSERT_TRUE(daemon_.DiskStatsReadStats(&read_sectors_now,
+                                         &write_sectors_now));
+  EXPECT_EQ(read_sectors_now, kFakeReadSectors[0]);
+  EXPECT_EQ(write_sectors_now, kFakeWriteSectors[0]);
+
+  CreateFakeDiskStatsFile(kFakeDiskStats1);
+  ASSERT_TRUE(daemon_.DiskStatsReadStats(&read_sectors_now,
+                                         &write_sectors_now));
+  EXPECT_EQ(read_sectors_now, kFakeReadSectors[1]);
+  EXPECT_EQ(write_sectors_now, kFakeWriteSectors[1]);
+}
+
 TEST_F(MetricsDaemonTest, ProcessMeminfo) {
   string meminfo =
       "MemTotal:        2000000 kB\nMemFree:          500000 kB\n"