diff --git a/core/base_rules.mk b/core/base_rules.mk
index 87ef414..72278ce 100644
--- a/core/base_rules.mk
+++ b/core/base_rules.mk
@@ -34,14 +34,27 @@
   ifneq ($(LOCAL_IS_HOST_MODULE),true)
     $(error $(LOCAL_PATH): LOCAL_IS_HOST_MODULE must be "true" or empty, not "$(LOCAL_IS_HOST_MODULE)")
   endif
-  my_prefix := HOST_
+  ifeq ($(LOCAL_HOST_PREFIX),)
+    my_prefix := HOST_
+  else
+    my_prefix := $(LOCAL_HOST_PREFIX)
+  endif
   my_host := host-
 else
   my_prefix := TARGET_
   my_host :=
 endif
 
+ifeq ($(my_prefix),HOST_CROSS_)
+  my_host_cross := true
+else
+  my_host_cross :=
+endif
+
 my_module_tags := $(LOCAL_MODULE_TAGS)
+ifeq ($(my_host_cross),true)
+  my_module_tags :=
+endif
 
 ###########################################################
 ## Validate and define fallbacks for input LOCAL_* variables.
@@ -150,15 +163,18 @@
 my_register_name := $(LOCAL_MODULE)$($(my_prefix)2ND_ARCH_MODULE_SUFFIX)
 endif
 endif
+ifeq ($(my_host_cross),true)
+  my_register_name := host_cross_$(LOCAL_MODULE)
+endif
 # Make sure that this IS_HOST/CLASS/MODULE combination is unique.
 module_id := MODULE.$(if \
-    $(LOCAL_IS_HOST_MODULE),HOST,TARGET).$(LOCAL_MODULE_CLASS).$(my_register_name)
+    $(LOCAL_IS_HOST_MODULE),$($(my_prefix)OS),TARGET).$(LOCAL_MODULE_CLASS).$(my_register_name)
 ifdef $(module_id)
 $(error $(LOCAL_PATH): $(module_id) already defined by $($(module_id)))
 endif
 $(module_id) := $(LOCAL_PATH)
 
-intermediates := $(call local-intermediates-dir,,$(LOCAL_2ND_ARCH_VAR_PREFIX))
+intermediates := $(call local-intermediates-dir,,$(LOCAL_2ND_ARCH_VAR_PREFIX),$(my_host_cross))
 intermediates.COMMON := $(call local-intermediates-dir,COMMON)
 generated_sources_dir := $(call local-generated-sources-dir)
 
@@ -225,6 +241,8 @@
 $(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_PATH:=$(LOCAL_PATH)
 $(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_IS_HOST_MODULE := $(LOCAL_IS_HOST_MODULE)
 $(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_HOST:= $(my_host)
+$(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_PREFIX := $(my_prefix)
+
 $(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_INTERMEDIATES_DIR:= $(intermediates)
 $(LOCAL_INTERMEDIATE_TARGETS) : PRIVATE_2ND_ARCH_VAR_PREFIX := $(LOCAL_2ND_ARCH_VAR_PREFIX)
 
@@ -358,6 +376,7 @@
 ifdef LOCAL_2ND_ARCH_VAR_PREFIX
 ALL_MODULES.$(my_register_name).FOR_2ND_ARCH := true
 endif
+ALL_MODULES.$(my_register_name).FOR_HOST_CROSS := $(my_host_cross)
 
 INSTALLABLE_FILES.$(LOCAL_INSTALLED_MODULE).MODULE := $(my_register_name)
 
diff --git a/core/binary.mk b/core/binary.mk
index cb045cc..4bf31ad 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -145,7 +145,7 @@
 # MinGW spits out warnings about -fPIC even for -fpie?!) being ignored because
 # all code is position independent, and then those warnings get promoted to
 # errors.
-ifndef USE_MINGW
+ifneq ($($(my_prefix)OS),windows)
 ifeq ($(LOCAL_MODULE_CLASS),EXECUTABLES)
 my_cflags += -fpie
 else
@@ -186,11 +186,20 @@
 # clang is enabled by default for host builds
 # enable it unless we've specifically disabled clang above
 ifdef LOCAL_IS_HOST_MODULE
-    ifneq ($(HOST_OS),windows)
+    ifneq ($($(my_prefix)OS),windows)
     ifeq ($(my_clang),)
         my_clang := true
     endif
     endif
+# Add option to make clang the default for device build
+else ifeq ($(USE_CLANG_PLATFORM_BUILD),true)
+    ifeq ($(my_clang),)
+        my_clang := true
+    endif
+endif
+
+ifeq ($(strip $($(LOCAL_2ND_ARCH_VAR_PREFIX)WITHOUT_$(my_prefix)CLANG)),true)
+  my_clang :=
 endif
 
 my_cpp_std_version := -std=gnu++14
@@ -209,12 +218,6 @@
 
 my_cppflags := $(my_cpp_std_version) $(my_cppflags)
 
-# Add option to make clang the default for device build
-ifeq ($(USE_CLANG_PLATFORM_BUILD),true)
-    ifeq ($(my_clang),)
-        my_clang := true
-    endif
-endif
 
 # arch-specific static libraries go first so that generic ones can depend on them
 my_static_libraries := $(LOCAL_STATIC_LIBRARIES_$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH)) $(LOCAL_STATIC_LIBRARIES_$(my_32_64_bit_suffix)) $(my_static_libraries)
@@ -235,10 +238,6 @@
 
 include $(BUILD_SYSTEM)/config_sanitizers.mk
 
-ifeq ($(strip $($(LOCAL_2ND_ARCH_VAR_PREFIX)WITHOUT_$(my_prefix)CLANG)),true)
-  my_clang :=
-endif
-
 # Add in libcompiler_rt for all regular device builds
 ifeq (,$(LOCAL_SDK_VERSION)$(WITHOUT_LIBCOMPILER_RT))
   my_static_libraries += $(COMPILER_RT_CONFIG_EXTRA_STATIC_LIBRARIES)
@@ -307,17 +306,17 @@
 else # LOCAL_IS_HOST_MODULE
 
 ifeq ($(my_clang),true)
-my_host_global_cflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_HOST_GLOBAL_CFLAGS)
-my_host_global_conlyflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_HOST_GLOBAL_CONLYFLAGS)
-my_host_global_cppflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_HOST_GLOBAL_CPPFLAGS)
-my_host_global_ldflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_HOST_GLOBAL_LDFLAGS)
-my_host_c_includes := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_C_INCLUDES)
+my_host_global_cflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_$(my_prefix)GLOBAL_CFLAGS)
+my_host_global_conlyflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_$(my_prefix)GLOBAL_CONLYFLAGS)
+my_host_global_cppflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_$(my_prefix)GLOBAL_CPPFLAGS)
+my_host_global_ldflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)CLANG_$(my_prefix)GLOBAL_LDFLAGS)
+my_host_c_includes := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)C_INCLUDES)
 else
-my_host_global_cflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_CFLAGS)
-my_host_global_conlyflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_CONLYFLAGS)
-my_host_global_cppflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_CPPFLAGS)
-my_host_global_ldflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_LDFLAGS)
-my_host_c_includes := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_C_INCLUDES)
+my_host_global_cflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)GLOBAL_CFLAGS)
+my_host_global_conlyflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)GLOBAL_CONLYFLAGS)
+my_host_global_cppflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)GLOBAL_CPPFLAGS)
+my_host_global_ldflags := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)GLOBAL_LDFLAGS)
+my_host_c_includes := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)C_INCLUDES)
 endif # my_clang
 
 $(LOCAL_INTERMEDIATE_TARGETS): PRIVATE_HOST_C_INCLUDES := $(my_host_c_includes)
@@ -618,13 +617,13 @@
     my_static_libraries += libprotobuf-c-nano
 else ifeq ($(LOCAL_PROTOC_OPTIMIZE_TYPE),full)
     ifdef LOCAL_SDK_VERSION
-        my_static_libraries += libprotobuf-cpp-full
+        my_static_libraries += libprotobuf-cpp-full-ndk
     else
         my_shared_libraries += libprotobuf-cpp-full
     endif
 else
     ifdef LOCAL_SDK_VERSION
-        my_static_libraries += libprotobuf-cpp-lite
+        my_static_libraries += libprotobuf-cpp-lite-ndk
     else
         my_shared_libraries += libprotobuf-cpp-lite
     endif
@@ -1015,9 +1014,9 @@
 import_includes := $(intermediates)/import_includes
 import_includes_deps := $(strip \
     $(foreach l, $(installed_shared_library_module_names), \
-      $(call intermediates-dir-for,SHARED_LIBRARIES,$(l),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX))/export_includes) \
+      $(call intermediates-dir-for,SHARED_LIBRARIES,$(l),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX),$(my_host_cross))/export_includes) \
     $(foreach l, $(my_static_libraries) $(my_whole_static_libraries), \
-      $(call intermediates-dir-for,STATIC_LIBRARIES,$(l),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX))/export_includes))
+      $(call intermediates-dir-for,STATIC_LIBRARIES,$(l),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX),$(my_host_cross))/export_includes))
 $(import_includes): PRIVATE_IMPORT_EXPORT_INCLUDES := $(import_includes_deps)
 $(import_includes) : $(LOCAL_MODULE_MAKEFILE) $(import_includes_deps)
 	@echo Import includes file: $@
@@ -1122,7 +1121,7 @@
 built_static_libraries := \
     $(foreach lib,$(my_static_libraries), \
       $(call intermediates-dir-for, \
-        STATIC_LIBRARIES,$(lib),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX))/$(lib)$(a_suffix))
+        STATIC_LIBRARIES,$(lib),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX),$(my_host_cross))/$(lib)$(a_suffix))
 
 ifdef LOCAL_SDK_VERSION
 built_static_libraries += $(my_ndk_stl_static_lib)
@@ -1131,7 +1130,7 @@
 built_whole_libraries := \
     $(foreach lib,$(my_whole_static_libraries), \
       $(call intermediates-dir-for, \
-        STATIC_LIBRARIES,$(lib),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX))/$(lib)$(a_suffix))
+        STATIC_LIBRARIES,$(lib),$(LOCAL_IS_HOST_MODULE),,$(LOCAL_2ND_ARCH_VAR_PREFIX),$(my_host_cross))/$(lib)$(a_suffix))
 
 # We don't care about installed static libraries, since the
 # libraries have already been linked into the module at that point.
diff --git a/core/build-system.html b/core/build-system.html
index caade58..3f638c3 100644
--- a/core/build-system.html
+++ b/core/build-system.html
@@ -462,26 +462,17 @@
 <p>Sometimes you need to set flags specifically for different platforms.  Here
 is a list of which values the different build-system defined variables will be
 set to and some examples.</p>
-<p>For a device build, <code>TARGET_OS</code> is <code>linux</code> (we're using
-linux!), and <code>TARGET_ARCH</code> is <code>arm</code>.</p>
-<p>For a simulator build, <code>TARGET_OS</code> and <code>TARGET_ARCH</code>
-are set to the same as <code>HOST_OS</code> and <code>HOST_ARCH</code> are
-on your platform.  <code>TARGET_PRODUCT</code> is the name of the target
-hardware/product you are building for.  The value <code>sim</code> is used
-for the simulator.  We haven't thought through the full extent of customization
-that will happen here, but likely there will be additional UI configurations
-specified here as well.</p>
 <table cellspacing=25>
 <tr>
     <td valign=top align=center>
         <b>HOST_OS</b><br/>
         linux<br/>
-        darwin<br/>
-        (cygwin)
+        darwin
     </td>
     <td valign=top align=center>
         <b>HOST_ARCH</b><br/>
-        x86
+        x86<br/>
+        x86_64
     </td>
     <td valign=top align=center>
         <b>HOST_BUILD_TYPE</b><br/>
@@ -491,42 +482,40 @@
 </tr>
 <tr>
     <td valign=top align=center>
-        <b>TARGET_OS</b><br/>
-        linux<br/>
-        darwin<br/>
-        (cygwin)
-    </td>
-    <td valign=top align=center>
         <b>TARGET_ARCH</b><br/>
         arm<br/>
-        x86
+        arm64<br/>
+        mips<br/>
+        mips64<br/>
+        x86<br/>
+        x86_64
     </td>
     <td valign=top align=center>
         <b>TARGET_BUILD_TYPE</b><br/>
         release<br/>
         debug
     </td>
-    <td valign=top align=center>
-        <b>TARGET_PRODUCT</b><br/>
-        sim<br/>
-        dream<br/>
-        sooner
-    </td>
 </tr>
 </table>
 
+<p>There are also special variables to use instead of conditionals. Many of the
+normal variables (LOCAL_SRC_FILES, LOCAL_CFLAGS, etc) can be conditionally added
+to with _{arch} _{32|64}, and for the host, _{os}.</p>
+
 <h4>Some Examples</h4>
 <pre>ifeq ($(TARGET_BUILD_TYPE),release)
 LOCAL_CFLAGS += -DNDEBUG=1
 endif
 
+LOCAL_CFLAGS_arm += -DTARGET_IS_ARM
+
+LOCAL_CFLAGS_64 += -DBIG_POINTER
+
 # from libutils
-ifeq ($(TARGET_OS),linux)
 # Use the futex based mutex and condition variable
 # implementation from android-arm because it's shared mem safe
-LOCAL_SRC_FILES += futex_synchro.c
-LOCAL_LDLIBS += -lrt -ldl
-endif
+LOCAL_SRC_FILES_linux += futex_synchro.c
+LOCAL_LDLIBS_linux += -lrt -ldl
 
 </pre>
 
@@ -554,7 +543,7 @@
 the unstripped executables so GDB can find the symbols.
 <code>LOCAL_UNSTRIPPED_PATH</code> is not necessary if you only specified
 <code>LOCAL_MODULE_RELATIVE_PATH</code>.</p>
-<p>Look in <code>config/envsetup.make</code> for all of the variables defining
+<p>Look in <code>core/envsetup.mk</code> for all of the variables defining
 places to build things.</p>
 <p>FYI: If you're installing an executable to /sbin, you probably also want to
 set <code>LOCAL_FORCE_STATIC_EXCUTABLE := true</code> in your Android.mk, which
@@ -587,6 +576,11 @@
     and definitions that are specific to either the host or the target builds.
     Do not set variables that start with HOST_ or TARGET_ in your makefiles.
     </li>
+    <li><b>HOST_CROSS_</b> - These contain the directories and definitions that
+    are specific to cross-building host binaries. The common case is building
+    windows host tools on linux. Do not set variables that start with
+    HOST_CROSS_ in your makefiles.
+    </li>
     <li><b>BUILD_</b> and <b>CLEAR_VARS</b> - These contain the names of
     well-defined template makefiles to include.  Some examples are CLEAR_VARS
     and BUILD_HOST_PACKAGE.</li>
@@ -773,13 +767,13 @@
 </code></p>
 
 <h4>LOCAL_PREBUILT_EXECUTABLES</h4>
-<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to
-executables that you want copied.  They're located automatically into the
+<p>When including $(BUILD_MULTI_PREBUILT) or $(BUILD_HOST_PREBUILT), set these
+to executables that you want copied.  They're located automatically into the
 right bin directory.</p>
 
 <h4>LOCAL_PREBUILT_LIBS</h4>
-<p>When including $(BUILD_PREBUILT) or $(BUILD_HOST_PREBUILT), set these to
-libraries that you want copied.  They're located automatically into the
+<p>When including $(BUILD_MULTI_PREBUILT) or $(BUILD_HOST_PREBUILT), set these
+to libraries that you want copied.  They're located automatically into the
 right lib directory.</p>
 
 <h4>LOCAL_SHARED_LIBRARIES</h4>
@@ -836,6 +830,16 @@
 the relative path.</p>
 <p>See <a href="#moving-modules">Putting modules elsewhere</a> for more.</p>
 
+<h4>LOCAL_MODULE_HOST_OS</h4>
+<p>This specifies which OSes are supported by this host module. It is not used
+for target builds. The accepted values here are combinations of
+<code>linux</code>, <code>darwin</code>, and <code>windows</code>. By default,
+linux and darwin(MacOS) are considered to be supported. If a module should
+build under windows, you must specify windows, and any others to be supported.
+Some examples:</p>
+<p><code>LOCAL_MODULE_HOST_OS := linux<br/>
+LOCAL_MODULE_HOST_OS := darwin linux windows</code></p>
+
 <h4>LOCAL_UNSTRIPPED_PATH</h4>
 <p>Instructs the build system to put the unstripped version of the module
 somewhere other than what's normal for its type.  Usually, you override this
@@ -878,10 +882,10 @@
 If you make a change that requires an update, you need to update two places
 so this message will be printed.
 <ul>
-    <li>In config/envsetup.make, increment the
+    <li>In core/envsetup.mk, increment the
         CORRECT_BUILD_ENV_SEQUENCE_NUMBER definition.</li>
     <li>In buildspec.mk.default, update the BUILD_ENV_SEQUENCE_DUMBER
-        definition to match the one in config/envsetup.make</li>
+        definition to match the one in core/envsetup.mk</li>
 </ul>
 The scripts automatically get the value from the build system, so they will
 trigger the warning as well.
@@ -900,53 +904,39 @@
 for some other dependency that isn't created automatically.</p>
 
 <h4>LOCAL_BUILT_MODULE</h4>
+<p class=warning>This should not be used, since multiple binaries are now
+created from a single module defintiion.</p>
 <p>When a module is built, the module is created in an intermediate
 directory then copied to its final location.  LOCAL_BUILT_MODULE is
 the full path to the intermediate file.  See LOCAL_INSTALLED_MODULE
 for the path to the final installed location of the module.</p>
 
-<h4>LOCAL_HOST</h4>
-<p>Set by the host_xxx.make includes to tell base_rules.make and the other
-includes that we're building for the host.  Kenneth did this as part of
-openbinder, and I would like to clean it up so the rules, includes and
-definitions aren't duplicated for host and target.</p>
+<h4>LOCAL_IS_HOST_MODULE</h4>
+<p>Set by the host_xxx.mk includes to tell base_rules.mk and the other
+includes that we're building for the host.</p>
 
 <h4>LOCAL_INSTALLED_MODULE</h4>
+<p class=warning>This should not be used, since multiple binaries are now
+created from a single module defintiion.</p>
 <p>The fully qualified path name of the final location of the module.
 See LOCAL_BUILT_MODULE for the location of the intermediate file that
 the make rules should actually be constructing.</p>
 
-<h4>LOCAL_REPLACE_VARS</h4>
-<p>Used in some stuff remaining from the openbinder for building scripts
-with particular values set,</p>
-
-<h4>LOCAL_SCRIPTS</h4>
-<p>Used in some stuff remaining from the openbinder build system that we
-might find handy some day.</p>
-
 <h4>LOCAL_MODULE_CLASS</h4>
 <p>Which kind of module this is.  This variable is used to construct other
-variable names used to locate the modules.  See base_rules.make and
-envsetup.make.</p>
-
-<h4>LOCAL_MODULE_NAME</h4>
-<p>Set to the leaf name of the LOCAL_BUILT_MODULE.  I'm not sure,
-but it looks like it's just used in the WHO_AM_I variable to identify
-in the pretty printing what's being built.</p>
+variable names used to locate the modules.  See base_rules.mk and
+envsetup.mk.</p>
 
 <h4>LOCAL_MODULE_SUFFIX</h4>
 <p>The suffix that will be appended to <code>LOCAL_MODULE</code> to form
 <code>LOCAL_MODULE_NAME</code>.  For example, .so, .a, .dylib.</p>
 
 <h4>LOCAL_STRIP_MODULE</h4>
-<p>Calculated in base_rules.make to determine if this module should actually
-be stripped or not, based on whether <code>LOCAL_STRIPPABLE_MODULE</code>
-is set, and whether the combo is configured to ever strip modules.  With
-Iliyan's stripping tool, this might change.</p>
-
-<h4>LOCAL_STRIPPABLE_MODULE</h4>
-<p>Set by the include makefiles if that type of module is strippable. 
-Executables and shared libraries are.</p>
+<p>If set to true (the default), the binary will be stripped and a debug
+link will be set up so that GDB will still work. If set to no_debuglink,
+the binary will be stripped, but no debug link will be added. If set to
+keep_symbols, it will strip the debug information, but keep the symbol table.
+Any other value will prevent stripping.</p>
 
 <h4>LOCAL_SYSTEM_SHARED_LIBRARIES</h4>
 <p>Used while building the base libraries: libc, libm, libdl.  Usually
diff --git a/core/ccache.mk b/core/ccache.mk
index 34e5e1c..c99d933 100644
--- a/core/ccache.mk
+++ b/core/ccache.mk
@@ -37,11 +37,6 @@
   export CCACHE_CPP2 := true
 
   CCACHE_HOST_TAG := $(HOST_PREBUILT_TAG)
-  # If we are cross-compiling Windows binaries on Linux
-  # then use the linux ccache binary instead.
-  ifeq ($(HOST_OS)-$(BUILD_OS),windows-linux)
-    CCACHE_HOST_TAG := linux-$(HOST_PREBUILT_ARCH)
-  endif
   ccache := prebuilts/misc/$(CCACHE_HOST_TAG)/ccache/ccache
   # Check that the executable is here.
   ccache := $(strip $(wildcard $(ccache)))
diff --git a/core/clang/HOST_CROSS_windows.mk b/core/clang/HOST_CROSS_windows.mk
new file mode 100644
index 0000000..74adb58
--- /dev/null
+++ b/core/clang/HOST_CROSS_windows.mk
@@ -0,0 +1,56 @@
+
+include $(BUILD_SYSTEM)/clang/x86.mk
+
+CLANG_CONFIG_x86_HOST_CROSS_TRIPLE := i686-pc-mingw32
+
+CLANG_CONFIG_x86_HOST_CROSS_EXTRA_ASFLAGS := \
+  $(CLANG_CONFIG_EXTRA_ASFLAGS) \
+  $(CLANG_CONFIG_HOST_CROSS_EXTRA_ASFLAGS) \
+  $(CLANG_CONFIG_x86_EXTRA_ASFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_COMBO_EXTRA_ASFLAGS) \
+  -target $(CLANG_CONFIG_x86_HOST_CROSS_TRIPLE)
+
+CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CFLAGS := \
+  $(CLANG_CONFIG_EXTRA_CFLAGS) \
+  $(CLANG_CONFIG_HOST_CROSS_EXTRA_CFLAGS) \
+  $(CLANG_CONFIG_x86_EXTRA_CFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_COMBO_EXTRA_CFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_EXTRA_ASFLAGS)
+
+CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CONLYFLAGS := \
+  $(CLANG_CONFIG_EXTRA_CONLYFLAGS) \
+  $(CLANG_CONFIG_HOST_CROSS_EXTRA_CONLYFLAGS) \
+  $(CLANG_CONFIG_x86_EXTRA_CONLYFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_COMBO_EXTRA_CONLYFLAGS)
+
+CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CPPFLAGS := \
+  $(CLANG_CONFIG_EXTRA_CPPFLAGS) \
+  $(CLANG_CONFIG_HOST_CROSS_EXTRA_CPPFLAGS) \
+  $(CLANG_CONFIG_x86_EXTRA_CPPFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_COMBO_EXTRA_CPPFLAGS) \
+  -target $(CLANG_CONFIG_x86_HOST_CROSS_TRIPLE)
+
+CLANG_CONFIG_x86_HOST_CROSS_EXTRA_LDFLAGS := \
+  $(CLANG_CONFIG_EXTRA_LDFLAGS) \
+  $(CLANG_CONFIG_HOST_CROSS_EXTRA_LDFLAGS) \
+  $(CLANG_CONFIG_x86_EXTRA_LDFLAGS) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_COMBO_EXTRA_LDFLAGS) \
+  -target $(CLANG_CONFIG_x86_HOST_CROSS_TRIPLE)
+
+CLANG_HOST_CROSS_GLOBAL_CFLAGS := \
+  $(call convert-to-host-clang-flags,$(HOST_CROSS_GLOBAL_CFLAGS)) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CFLAGS)
+
+CLANG_HOST_CROSS_GLOBAL_CONLYFLAGS := \
+  $(call convert-to-host-clang-flags,$(HOST_CROSS_GLOBAL_CONLYFLAGS)) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CONLYFLAGS)
+
+CLANG_HOST_CROSS_GLOBAL_CPPFLAGS := \
+  $(call convert-to-host-clang-flags,$(HOST_CROSS_GLOBAL_CPPFLAGS)) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_EXTRA_CPPFLAGS)
+
+CLANG_HOST_CROSS_GLOBAL_LDFLAGS := \
+  $(call convert-to-host-clang-flags,$(HOST_CROSS_GLOBAL_LDFLAGS)) \
+  $(CLANG_CONFIG_x86_HOST_CROSS_EXTRA_LDFLAGS)
+
+HOST_CROSS_LIBPROFILE_RT := $(LLVM_RTLIB_PATH)/libclang_rt.profile-i686.a
diff --git a/core/clang/HOST_x86.mk b/core/clang/HOST_x86.mk
index f14a9c3..0ec64ad 100644
--- a/core/clang/HOST_x86.mk
+++ b/core/clang/HOST_x86.mk
@@ -16,9 +16,6 @@
 CLANG_CONFIG_x86_HOST_COMBO_EXTRA_CPPFLAGS := $(CLANG_CONFIG_x86_DARWIN_HOST_EXTRA_CPPFLAGS)
 CLANG_CONFIG_x86_HOST_COMBO_EXTRA_LDFLAGS := $(CLANG_CONFIG_x86_DARWIN_HOST_EXTRA_LDFLAGS)
 endif
-ifeq ($(HOST_OS),windows)
-CLANG_CONFIG_x86_HOST_TRIPLE := i686-pc-mingw32
-endif
 
 CLANG_CONFIG_x86_HOST_EXTRA_ASFLAGS := \
   $(CLANG_CONFIG_EXTRA_ASFLAGS) \
diff --git a/core/clang/HOST_x86_64.mk b/core/clang/HOST_x86_64.mk
index 1211e73..d46cb67 100644
--- a/core/clang/HOST_x86_64.mk
+++ b/core/clang/HOST_x86_64.mk
@@ -16,9 +16,6 @@
 CLANG_CONFIG_x86_64_HOST_COMBO_EXTRA_CPPFLAGS := $(CLANG_CONFIG_x86_DARWIN_HOST_EXTRA_CPPFLAGS)
 CLANG_CONFIG_x86_64_HOST_COMBO_EXTRA_LDFLAGS := $(CLANG_CONFIG_x86_DARWIN_HOST_EXTRA_LDFLAGS)
 endif
-ifeq ($(HOST_OS),windows)
-CLANG_CONFIG_x86_64_HOST_TRIPLE := x86_64-pc-mingw64
-endif
 
 CLANG_CONFIG_x86_64_HOST_EXTRA_ASFLAGS := \
   $(CLANG_CONFIG_EXTRA_ASFLAGS) \
diff --git a/core/clang/HOST_x86_common.mk b/core/clang/HOST_x86_common.mk
index 74b5a69..fc98dd5 100644
--- a/core/clang/HOST_x86_common.mk
+++ b/core/clang/HOST_x86_common.mk
@@ -48,7 +48,3 @@
   -L$($(clang_2nd_arch_prefix)HOST_TOOLCHAIN_FOR_CLANG)/x86_64-linux/lib32/
 endif
 endif  # Linux
-
-ifeq ($(HOST_OS),windows)
-# nothing required here yet
-endif
diff --git a/core/clang/config.mk b/core/clang/config.mk
index 910c1a4..03d7730 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -84,6 +84,12 @@
 CLANG_CONFIG_HOST_EXTRA_CPPFLAGS :=
 CLANG_CONFIG_HOST_EXTRA_LDFLAGS :=
 
+# Clang flags for all host cross rules
+CLANG_CONFIG_HOST_CROSS_EXTRA_ASFLAGS :=
+CLANG_CONFIG_HOST_CROSS_EXTRA_CFLAGS :=
+CLANG_CONFIG_HOST_CROSS_EXTRA_CPPFLAGS :=
+CLANG_CONFIG_HOST_CROSS_EXTRA_LDFLAGS :=
+
 # Clang flags for all target rules
 CLANG_CONFIG_TARGET_EXTRA_ASFLAGS :=
 CLANG_CONFIG_TARGET_EXTRA_CFLAGS := -nostdlibinc
@@ -126,6 +132,10 @@
 include $(BUILD_SYSTEM)/clang/HOST_$(HOST_2ND_ARCH).mk
 endif
 
+ifdef HOST_CROSS_OS
+include $(BUILD_SYSTEM)/clang/HOST_CROSS_$(HOST_CROSS_OS).mk
+endif
+
 # TARGET config
 clang_2nd_arch_prefix :=
 include $(BUILD_SYSTEM)/clang/TARGET_$(TARGET_ARCH).mk
diff --git a/core/clear_vars.mk b/core/clear_vars.mk
index e2f1444..d0d4ff9 100644
--- a/core/clear_vars.mk
+++ b/core/clear_vars.mk
@@ -173,6 +173,13 @@
 LOCAL_MODULE_UNSUPPORTED_TARGET_ARCH:=
 LOCAL_MODULE_UNSUPPORTED_TARGET_ARCH_WARN:=
 LOCAL_MODULE_HOST_ARCH:=
+LOCAL_MODULE_HOST_ARCH_WARN:=
+LOCAL_MODULE_UNSUPPORTED_HOST_ARCH:=
+LOCAL_MODULE_UNSUPPORTED_HOST_ARCH_WARN:=
+LOCAL_MODULE_HOST_CROSS_ARCH:=
+LOCAL_MODULE_HOST_CROSS_ARCH_WARN:=
+LOCAL_MODULE_UNSUPPORTED_HOST_CROSS_ARCH:=
+LOCAL_MODULE_UNSUPPORTED_HOST_CROSS_ARCH_WARN:=
 LOCAL_NO_FPIE :=
 LOCAL_CXX_STL := default
 LOCAL_NATIVE_COVERAGE :=
@@ -268,10 +275,27 @@
 LOCAL_GENERATED_SOURCES_$(HOST_OS):=
 LOCAL_REQUIRED_MODULES_$(HOST_OS):=
 
+ifdef HOST_CROSS_OS
+LOCAL_SRC_FILES_$(HOST_CROSS_OS):=
+LOCAL_STATIC_LIBRARIES_$(HOST_CROSS_OS):=
+LOCAL_SHARED_LIBRARIES_$(HOST_CROSS_OS):=
+LOCAL_CFLAGS_$(HOST_CROSS_OS):=
+LOCAL_CPPFLAGS_$(HOST_CROSS_OS):=
+LOCAL_LDFLAGS_$(HOST_CROSS_OS):=
+LOCAL_LDLIBS_$(HOST_CROSS_OS):=
+LOCAL_ASFLAGS_$(HOST_CROSS_OS):=
+LOCAL_C_INCLUDES_$(HOST_CROSS_OS):=
+LOCAL_GENERATED_SOURCES_$(HOST_CROSS_OS):=
+LOCAL_REQUIRED_MODULES_$(HOST_CROSS_OS):=
+endif
+
 LOCAL_SRC_FILES_$(HOST_OS)_$(HOST_ARCH):=
 ifdef HOST_2ND_ARCH
 LOCAL_SRC_FILES_$(HOST_OS)_$(HOST_2ND_ARCH):=
 endif
+ifdef HOST_CROSS_OS
+LOCAL_SRC_FILES_$(HOST_CROSS_OS)_$(HOST_CROSS_ARCH):=
+endif
 
 LOCAL_SRC_FILES_32:=
 LOCAL_SRC_FILES_64:=
diff --git a/core/combo/HOST_CROSS_windows-x86.mk b/core/combo/HOST_CROSS_windows-x86.mk
new file mode 100644
index 0000000..f509594
--- /dev/null
+++ b/core/combo/HOST_CROSS_windows-x86.mk
@@ -0,0 +1,55 @@
+#
+# Copyright (C) 2006 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# Settings to use MinGW as a cross-compiler under Linux
+# Included by combo/select.make
+
+$(combo_var_prefix)GLOBAL_CFLAGS += -DUSE_MINGW -DWIN32_LEAN_AND_MEAN
+$(combo_var_prefix)GLOBAL_CFLAGS += -Wno-unused-parameter
+$(combo_var_prefix)GLOBAL_CFLAGS += --sysroot=prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32
+$(combo_var_prefix)GLOBAL_CFLAGS += -m32
+$(combo_var_prefix)GLOBAL_LDFLAGS += -m32
+TOOLS_PREFIX := prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/bin/x86_64-w64-mingw32-
+$(combo_var_prefix)C_INCLUDES += prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32/include
+$(combo_var_prefix)C_INCLUDES += prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/lib/gcc/x86_64-w64-mingw32/4.8.3/include
+$(combo_var_prefix)GLOBAL_LD_DIRS += -Lprebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32/lib32
+
+# Workaround differences in inttypes.h between host and target.
+# See bug 12708004.
+$(combo_var_prefix)GLOBAL_CFLAGS += -D__STDC_FORMAT_MACROS -D__STDC_CONSTANT_MACROS
+# Use C99-compliant printf functions (%zd).
+$(combo_var_prefix)GLOBAL_CFLAGS += -D__USE_MINGW_ANSI_STDIO=1
+# Admit to using >= Win2K.
+$(combo_var_prefix)GLOBAL_CFLAGS += -D_WIN32_WINNT=0x0500
+# Get 64-bit off_t and related functions.
+$(combo_var_prefix)GLOBAL_CFLAGS += -D_FILE_OFFSET_BITS=64
+
+$(combo_var_prefix)CC := $(TOOLS_PREFIX)gcc
+$(combo_var_prefix)CXX := $(TOOLS_PREFIX)g++
+$(combo_var_prefix)AR := $(TOOLS_PREFIX)ar
+
+$(combo_var_prefix)GLOBAL_LDFLAGS += \
+    --enable-stdcall-fixup
+
+ifneq ($(strip $(BUILD_HOST_static)),)
+# Statically-linked binaries are desirable for sandboxed environment
+$(combo_var_prefix)GLOBAL_LDFLAGS += -static
+endif # BUILD_HOST_static
+
+$(combo_var_prefix)SHLIB_SUFFIX := .dll
+$(combo_var_prefix)EXECUTABLE_SUFFIX := .exe
+
+$(combo_var_prefix)IS_64_BIT :=
diff --git a/core/combo/HOST_windows-x86.mk b/core/combo/HOST_windows-x86.mk
deleted file mode 100644
index 30c1c75..0000000
--- a/core/combo/HOST_windows-x86.mk
+++ /dev/null
@@ -1,62 +0,0 @@
-#
-# Copyright (C) 2006 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-# Settings to use MinGW as a cross-compiler under Linux
-# Included by combo/select.make
-
-HOST_ACP_UNAVAILABLE := true
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -DUSE_MINGW -DWIN32_LEAN_AND_MEAN
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -Wno-unused-parameter
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += --sysroot=prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -m32
-$(combo_2nd_arch_prefix)HOST_GLOBAL_LDFLAGS += -m32
-TOOLS_PREFIX := prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/bin/x86_64-w64-mingw32-
-$(combo_2nd_arch_prefix)HOST_C_INCLUDES += prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32/include
-$(combo_2nd_arch_prefix)HOST_C_INCLUDES += prebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/lib/gcc/x86_64-w64-mingw32/4.8.3/include
-$(combo_2nd_arch_prefix)HOST_GLOBAL_LD_DIRS += -Lprebuilts/gcc/linux-x86/host/x86_64-w64-mingw32-4.8/x86_64-w64-mingw32/lib32
-
-# Workaround differences in inttypes.h between host and target.
-# See bug 12708004.
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -D__STDC_FORMAT_MACROS -D__STDC_CONSTANT_MACROS
-# Use C99-compliant printf functions (%zd).
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -D__USE_MINGW_ANSI_STDIO=1
-# Admit to using >= Win2K.
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -D_WIN32_WINNT=0x0500
-# Get 64-bit off_t and related functions.
-$(combo_2nd_arch_prefix)HOST_GLOBAL_CFLAGS += -D_FILE_OFFSET_BITS=64
-
-$(combo_2nd_arch_prefix)HOST_CC := $(TOOLS_PREFIX)gcc$(TOOLS_EXE_SUFFIX)
-$(combo_2nd_arch_prefix)HOST_CXX := $(TOOLS_PREFIX)g++$(TOOLS_EXE_SUFFIX)
-$(combo_2nd_arch_prefix)HOST_AR := $(TOOLS_PREFIX)ar$(TOOLS_EXE_SUFFIX)
-
-$(combo_2nd_arch_prefix)HOST_GLOBAL_LDFLAGS += \
-    --enable-stdcall-fixup
-
-ifneq ($(strip $(BUILD_HOST_static)),)
-# Statically-linked binaries are desirable for sandboxed environment
-$(combo_2nd_arch_prefix)HOST_GLOBAL_LDFLAGS += -static
-endif # BUILD_HOST_static
-
-############################################################
-## Macros after this line are shared by the 64-bit config.
-
-HOST_SHLIB_SUFFIX := .dll
-HOST_EXECUTABLE_SUFFIX := .exe
-
-# $(1): The file to check
-define get-file-size
-stat --format "%s" "$(1)" | tr -d '\n'
-endef
diff --git a/core/combo/HOST_windows-x86_64.mk b/core/combo/HOST_windows-x86_64.mk
deleted file mode 100644
index 49b74e2..0000000
--- a/core/combo/HOST_windows-x86_64.mk
+++ /dev/null
@@ -1,45 +0,0 @@
-#
-# Copyright (C) 2006 The Android Open Source Project
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-# Settings to use MinGW as a cross-compiler under Linux
-# Included by combo/select.make
-
-# right now we get these from the environment, but we should
-# pick them from the tree somewhere
-TOOLS_PREFIX := /usr/bin/amd64-mingw32msvc-
-
-HOST_ACP_UNAVAILABLE := true
-HOST_GLOBAL_CFLAGS += -DUSE_MINGW
-HOST_C_INCLUDES += /usr/lib/gcc/amd64-mingw32msvc/4.4.2/include
-HOST_GLOBAL_LD_DIRS += -L/usr/amd64-mingw32msvc/lib
-
-# Workaround differences in inttypes.h between host and target.
-# See bug 12708004.
-HOST_GLOBAL_CFLAGS += -D__STDC_FORMAT_MACROS -D__STDC_CONSTANT_MACROS
-# Use C99-compliant printf functions (%zd).
-HOST_GLOBAL_CFLAGS += -D__USE_MINGW_ANSI_STDIO=1
-# Admit to using >= Win2K.
-HOST_GLOBAL_CFLAGS += -D_WIN32_WINNT=0x0500
-
-HOST_CC := $(TOOLS_PREFIX)gcc$(TOOLS_EXE_SUFFIX)
-HOST_CXX := $(TOOLS_PREFIX)g++$(TOOLS_EXE_SUFFIX)
-HOST_AR := $(TOOLS_PREFIX)ar$(TOOLS_EXE_SUFFIX)
-
-HOST_GLOBAL_LDFLAGS += --enable-stdcall-fixup
-ifneq ($(strip $(BUILD_HOST_static)),)
-# Statically-linked binaries are desirable for sandboxed environment
-HOST_GLOBAL_LDFLAGS += -static
-endif # BUILD_HOST_static
diff --git a/core/config.mk b/core/config.mk
index 6fb490c..e7a1d20 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -257,6 +257,13 @@
 include $(BUILD_SYSTEM)/combo/select.mk
 endif
 
+# Load the windows cross compiler under Linux
+ifdef HOST_CROSS_OS
+combo_target := HOST_CROSS_
+combo_2nd_arch_prefix :=
+include $(BUILD_SYSTEM)/combo/select.mk
+endif
+
 # on windows, the tools have .exe at the end, and we depend on the
 # host config stuff being done first
 
@@ -603,6 +610,17 @@
 $(HOST_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_CPPFLAGS += $($(HOST_2ND_ARCH_VAR_PREFIX)HOST_RELEASE_CPPFLAGS)
 endif
 
+ifdef HOST_CROSS_OS
+HOST_CROSS_GLOBAL_CFLAGS += $(COMMON_GLOBAL_CFLAGS)
+HOST_CROSS_RELEASE_CFLAGS += $(COMMON_RELEASE_CFLAGS)
+HOST_CROSS_GLOBAL_CPPFLAGS += $(COMMON_GLOBAL_CPPFLAGS)
+HOST_CROSS_RELEASE_CPPFLAGS += $(COMMON_RELEASE_CPPFLAGS)
+HOST_CROSS_GLOBAL_LD_DIRS += -L$(HOST_CROSS_OUT_INTERMEDIATE_LIBRARIES)
+HOST_CROSS_PROJECT_INCLUDES:= $(SRC_HEADERS) $(SRC_HOST_HEADERS) $(HOST_CROSS_OUT_HEADERS)
+HOST_CROSS_GLOBAL_CFLAGS += $(HOST_CROSS_RELEASE_CFLAGS)
+HOST_CROSS_GLOBAL_CPPFLAGS += $(HOST_CROSS_RELEASE_CPPFLAGS)
+endif
+
 # allow overriding default Java libraries on a per-target basis
 ifeq ($(TARGET_DEFAULT_JAVA_LIBRARIES),)
   TARGET_DEFAULT_JAVA_LIBRARIES := core-libart core-junit ext framework okhttp
diff --git a/core/cxx_stl_setup.mk b/core/cxx_stl_setup.mk
index cda45a0..bf492d5 100644
--- a/core/cxx_stl_setup.mk
+++ b/core/cxx_stl_setup.mk
@@ -1,6 +1,6 @@
 #############################################################
 ## Set up flags based on LOCAL_CXX_STL.
-## Input variables: LOCAL_CXX_STL
+## Input variables: LOCAL_CXX_STL, my_prefix
 ## Output variables: My_cflags, my_c_includes, my_shared_libraries, etc.
 #############################################################
 
@@ -47,10 +47,14 @@
 endif
 
 # Yes, this is actually what the clang driver does.
-HOST_linux_dynamic_gcclibs := -lgcc_s -lgcc -lc -lgcc_s -lgcc
-HOST_linux_static_gcclibs := -Wl,--start-group -lgcc -lgcc_eh -lc -Wl,--end-group
-HOST_darwin_dynamic_gcclibs := -lc -lSystem
-HOST_darwin_static_gcclibs := NO_STATIC_HOST_BINARIES_ON_DARWIN
+linux_dynamic_gcclibs := -lgcc_s -lgcc -lc -lgcc_s -lgcc
+linux_static_gcclibs := -Wl,--start-group -lgcc -lgcc_eh -lc -Wl,--end-group
+darwin_dynamic_gcclibs := -lc -lSystem
+darwin_static_gcclibs := NO_STATIC_HOST_BINARIES_ON_DARWIN
+windows_dynamic_gcclibs := \
+    -lmsvcr110 -lmingw32 -lgcc -lmoldname -lmingwex -lmsvcrt -ladvapi32 \
+    -lshell32 -luser32 -lkernel32 -lmingw32 -lgcc -lmoldname -lmingwex -lmsvcrt
+windows_static_gcclibs := NO_STATIC_HOST_BINARIES_ON_WINDOWS
 
 my_link_type := dynamic
 ifdef LOCAL_IS_HOST_MODULE
@@ -86,7 +90,7 @@
         my_cppflags += -nostdinc++
         my_ldflags += -nodefaultlibs
         my_ldlibs += -lpthread -lm
-        my_ldlibs += $($(my_prefix)$(HOST_OS)_$(my_link_type)_gcclibs)
+        my_ldlibs += $($($(my_prefix)OS)_$(my_link_type)_gcclibs)
     else
         ifeq (arm,$($(my_prefix)$(LOCAL_2ND_ARCH_VAR_PREFIX)ARCH))
             my_static_libraries += libunwind_llvm
@@ -116,7 +120,7 @@
     ifdef LOCAL_IS_HOST_MODULE
         my_cppflags += -nostdinc++
         my_ldflags += -nodefaultlibs
-        my_ldlibs += $($(my_prefix)$(HOST_OS)_$(my_link_type)_gcclibs)
+        my_ldlibs += $($($(my_prefix)OS)_$(my_link_type)_gcclibs)
     endif
 else
     $(error $(LOCAL_PATH): $(LOCAL_MODULE): $(my_cxx_stl) is not a supported STL.)
diff --git a/core/definitions.mk b/core/definitions.mk
index 8480512..f56a49b 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -87,11 +87,17 @@
 $(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_DEPENDENCIES_ON_SHARED_LIBRARIES :=
 HOST_DEPENDENCIES_ON_SHARED_LIBRARIES :=
 $(HOST_2ND_ARCH_VAR_PREFIX)HOST_DEPENDENCIES_ON_SHARED_LIBRARIES :=
+HOST_CROSS_DEPENDENCIES_ON_SHARED_LIBRARIES :=
 
 # Generated class file names for Android resource.
 # They are escaped and quoted so can be passed safely to a bash command.
 ANDROID_RESOURCE_GENERATED_CLASSES := 'R.class' 'R$$*.class' 'Manifest.class' 'Manifest$$*.class'
 
+# Display names for various build targets
+TARGET_DISPLAY := target
+HOST_DISPLAY := host
+HOST_CROSS_DISPLAY := host cross
+
 ###########################################################
 ## Debugging; prints a variable list to stdout
 ###########################################################
@@ -422,7 +428,8 @@
 # $(2): target name, like "NotePad"
 # $(3): if non-empty, this is a HOST target.
 # $(4): if non-empty, force the intermediates to be COMMON
-# $(5): if non-empty, force the intermedistes to be for the 2nd arch
+# $(5): if non-empty, force the intermediates to be for the 2nd arch
+# $(6): if non-empty, force the intermediates to be for the host cross os
 define intermediates-dir-for
 $(strip \
     $(eval _idfClass := $(strip $(1))) \
@@ -431,7 +438,7 @@
     $(eval _idfName := $(strip $(2))) \
     $(if $(_idfName),, \
         $(error $(LOCAL_PATH): Name not defined in call to intermediates-dir-for)) \
-    $(eval _idfPrefix := $(if $(strip $(3)),HOST,TARGET)) \
+    $(eval _idfPrefix := $(if $(strip $(3)),$(if $(strip $(6)),HOST_CROSS,HOST),TARGET)) \
     $(eval _idf2ndArchPrefix := $(if $(strip $(5)),$(TARGET_2ND_ARCH_VAR_PREFIX))) \
     $(if $(filter $(_idfPrefix)-$(_idfClass),$(COMMON_MODULE_CLASSES))$(4), \
         $(eval _idfIntBase := $($(_idfPrefix)_OUT_COMMON_INTERMEDIATES)) \
@@ -449,13 +456,14 @@
 #
 # $(1): if non-empty, force the intermediates to be COMMON
 # $(2): if non-empty, force the intermediates to be for the 2nd arch
+# $(3): if non-empty, force the intermediates to be for the host cross os
 define local-intermediates-dir
 $(strip \
     $(if $(strip $(LOCAL_MODULE_CLASS)),, \
         $(error $(LOCAL_PATH): LOCAL_MODULE_CLASS not defined before call to local-intermediates-dir)) \
     $(if $(strip $(LOCAL_MODULE)),, \
         $(error $(LOCAL_PATH): LOCAL_MODULE not defined before call to local-intermediates-dir)) \
-    $(call intermediates-dir-for,$(LOCAL_MODULE_CLASS),$(LOCAL_MODULE),$(LOCAL_IS_HOST_MODULE),$(1),$(2)) \
+    $(call intermediates-dir-for,$(LOCAL_MODULE_CLASS),$(LOCAL_MODULE),$(LOCAL_IS_HOST_MODULE),$(1),$(2),$(3)) \
 )
 endef
 
@@ -1106,7 +1114,7 @@
 ###########################################################
 
 define transform-host-cpp-to-o
-@echo "host C++: $(PRIVATE_MODULE) <= $<"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) C++: $(PRIVATE_MODULE) <= $<"
 @mkdir -p $(dir $@)
 $(hide) $(PRIVATE_CXX) \
 	$(addprefix -I , $(PRIVATE_C_INCLUDES)) \
@@ -1114,7 +1122,7 @@
 	$(addprefix -isystem ,\
 	    $(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
 	        $(filter-out $(PRIVATE_C_INCLUDES), \
-	            $(HOST_PROJECT_INCLUDES) \
+	            $($(PRIVATE_PREFIX)PROJECT_INCLUDES) \
 	            $(PRIVATE_HOST_C_INCLUDES)))) \
 	-c \
 	$(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
@@ -1144,7 +1152,7 @@
 	$(addprefix -isystem ,\
 	    $(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
 	        $(filter-out $(PRIVATE_C_INCLUDES), \
-	            $(HOST_PROJECT_INCLUDES) \
+	            $($(PRIVATE_PREFIX)PROJECT_INCLUDES) \
 	            $(PRIVATE_HOST_C_INCLUDES)))) \
 	-c \
 	$(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
@@ -1157,12 +1165,12 @@
 endef
 
 define transform-host-c-to-o-no-deps
-@echo "host C: $(PRIVATE_MODULE) <= $<"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) C: $(PRIVATE_MODULE) <= $<"
 $(call transform-host-c-or-s-to-o-no-deps, $(PRIVATE_CFLAGS) $(PRIVATE_CONLYFLAGS) $(PRIVATE_DEBUG_CFLAGS))
 endef
 
 define transform-host-s-to-o-no-deps
-@echo "host asm: $(PRIVATE_MODULE) <= $<"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) asm: $(PRIVATE_MODULE) <= $<"
 $(call transform-host-c-or-s-to-o-no-deps, $(PRIVATE_ASFLAGS))
 endef
 
@@ -1181,7 +1189,7 @@
 ###########################################################
 
 define transform-host-m-to-o-no-deps
-@echo "host ObjC: $(PRIVATE_MODULE) <= $<"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) ObjC: $(PRIVATE_MODULE) <= $<"
 $(call transform-host-c-or-s-to-o-no-deps, $(PRIVATE_CFLAGS) $(PRIVATE_DEBUG_CFLAGS))
 endef
 
@@ -1338,19 +1346,19 @@
     lib_to_include=$$ldir/$(notdir $(1)); \
     filelist=; \
     subdir=0; \
-    for f in `$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_AR) t $(1) | \grep '\.o$$'`; do \
+    for f in `$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)AR) t $(1) | \grep '\.o$$'`; do \
         if [ -e $$ldir/$$f ]; then \
            mkdir $$ldir/$$subdir; \
            ext=$$subdir/; \
            subdir=$$((subdir+1)); \
-           $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_AR) m $$lib_to_include $$f; \
+           $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)AR) m $$lib_to_include $$f; \
         else \
            ext=; \
         fi; \
-        $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_AR) p $$lib_to_include $$f > $$ldir/$$ext$$f; \
+        $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)AR) p $$lib_to_include $$f > $$ldir/$$ext$$f; \
         filelist="$$filelist $$ldir/$$ext$$f"; \
     done ; \
-    $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_AR) $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_ARFLAGS) \
+    $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)AR) $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)GLOBAL_ARFLAGS) \
         $(PRIVATE_ARFLAGS) $@ $$filelist
 
 endef
@@ -1364,12 +1372,12 @@
 # Explicitly delete the archive first so that ar doesn't
 # try to add to an existing archive.
 define transform-host-o-to-static-lib
-@echo "host StaticLib: $(PRIVATE_MODULE) ($@)"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) StaticLib: $(PRIVATE_MODULE) ($@)"
 @mkdir -p $(dir $@)
 @rm -f $@
 $(extract-and-include-host-whole-static-libs)
-$(call split-long-arguments,$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_AR) \
-    $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_ARFLAGS) \
+$(call split-long-arguments,$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)AR) \
+    $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)GLOBAL_ARFLAGS) \
     $(PRIVATE_ARFLAGS) $@,$(PRIVATE_ALL_OBJECTS))
 endef
 
@@ -1383,11 +1391,11 @@
 ifneq ($(HOST_CUSTOM_LD_COMMAND),true)
 define transform-host-o-to-shared-lib-inner
 $(hide) $(PRIVATE_CXX) \
-	-Wl,-rpath-link=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_INTERMEDIATE_LIBRARIES) \
-	-Wl,-rpath,\$$ORIGIN/../$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_SHARED_LIBRARIES)) \
-	-Wl,-rpath,\$$ORIGIN/$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_SHARED_LIBRARIES)) \
+	-Wl,-rpath-link=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_INTERMEDIATE_LIBRARIES) \
+	-Wl,-rpath,\$$ORIGIN/../$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_SHARED_LIBRARIES)) \
+	-Wl,-rpath,\$$ORIGIN/$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_SHARED_LIBRARIES)) \
 	-shared -Wl,-soname,$(notdir $@) \
-	$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_LD_DIRS) \
+	$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)GLOBAL_LD_DIRS) \
 	$(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
 	   $(PRIVATE_HOST_GLOBAL_LDFLAGS) \
 	) \
@@ -1408,13 +1416,13 @@
 endif
 
 define transform-host-o-to-shared-lib
-@echo "host SharedLib: $(PRIVATE_MODULE) ($@)"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) SharedLib: $(PRIVATE_MODULE) ($@)"
 @mkdir -p $(dir $@)
 $(transform-host-o-to-shared-lib-inner)
 endef
 
 define transform-host-o-to-package
-@echo "host Package: $(PRIVATE_MODULE) ($@)"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) Package: $(PRIVATE_MODULE) ($@)"
 @mkdir -p $(dir $@)
 $(transform-host-o-to-shared-lib-inner)
 endef
@@ -1582,8 +1590,8 @@
 else
 HOST_FPIE_FLAGS := -pie
 # Force the correct entry point to workaround a bug in binutils that manifests with -pie
-ifeq ($(HOST_OS),windows)
-HOST_FPIE_FLAGS += -Wl,-e_mainCRTStartup
+ifeq ($(HOST_CROSS_OS),windows)
+HOST_CROSS_FPIE_FLAGS += -Wl,-e_mainCRTStartup
 endif
 endif
 
@@ -1600,10 +1608,10 @@
 	$(if $(filter true,$(NATIVE_COVERAGE)),-lgcov) \
 	$(if $(filter true,$(NATIVE_COVERAGE)),$(PRIVATE_HOST_LIBPROFILE_RT)) \
 	$(call normalize-host-libraries,$(PRIVATE_ALL_SHARED_LIBRARIES)) \
-	-Wl,-rpath-link=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_INTERMEDIATE_LIBRARIES) \
-	-Wl,-rpath,\$$ORIGIN/../$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_SHARED_LIBRARIES)) \
-	-Wl,-rpath,\$$ORIGIN/$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_OUT_SHARED_LIBRARIES)) \
-	$($(PRIVATE_2ND_ARCH_VAR_PREFIX)HOST_GLOBAL_LD_DIRS) \
+	-Wl,-rpath-link=$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_INTERMEDIATE_LIBRARIES) \
+	-Wl,-rpath,\$$ORIGIN/../$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_SHARED_LIBRARIES)) \
+	-Wl,-rpath,\$$ORIGIN/$(notdir $($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)OUT_SHARED_LIBRARIES)) \
+	$($(PRIVATE_2ND_ARCH_VAR_PREFIX)$(PRIVATE_PREFIX)GLOBAL_LD_DIRS) \
 	$(if $(PRIVATE_NO_DEFAULT_COMPILER_FLAGS),, \
 		$(PRIVATE_HOST_GLOBAL_LDFLAGS) \
 	) \
@@ -1614,7 +1622,7 @@
 endif
 
 define transform-host-o-to-executable
-@echo "host Executable: $(PRIVATE_MODULE) ($@)"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) Executable: $(PRIVATE_MODULE) ($@)"
 @mkdir -p $(dir $@)
 $(transform-host-o-to-executable-inner)
 endef
@@ -2105,7 +2113,7 @@
 # Note: we intentionally don't clean PRIVATE_CLASS_INTERMEDIATES_DIR
 # in transform-java-to-classes for the sake of vm-tests.
 define transform-host-java-to-package
-@echo "host Java: $(PRIVATE_MODULE) ($(PRIVATE_CLASS_INTERMEDIATES_DIR))"
+@echo "$($(PRIVATE_PREFIX)DISPLAY) Java: $(PRIVATE_MODULE) ($(PRIVATE_CLASS_INTERMEDIATES_DIR))"
 $(call compile-java,$(HOST_JAVAC),$(PRIVATE_BOOTCLASSPATH))
 endef
 
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index aae2aba..893461a 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -23,6 +23,7 @@
 LOCAL_IS_HOST_MODULE := $(call true-or-empty,$(LOCAL_IS_HOST_MODULE))
 ifeq ($(LOCAL_IS_HOST_MODULE),true)
 my_prefix := HOST_
+LOCAL_HOST_PREFIX :=
 else
 my_prefix := TARGET_
 endif
diff --git a/core/dumpvar.mk b/core/dumpvar.mk
index 510bc7d..c7fb8db 100644
--- a/core/dumpvar.mk
+++ b/core/dumpvar.mk
@@ -80,6 +80,7 @@
 $(info   HOST_ARCH=$(HOST_ARCH))
 $(info   HOST_OS=$(HOST_OS))
 $(info   HOST_OS_EXTRA=$(HOST_OS_EXTRA))
+$(info   HOST_CROSS_OS=$(HOST_CROSS_OS))
 $(info   HOST_BUILD_TYPE=$(HOST_BUILD_TYPE))
 $(info   BUILD_ID=$(BUILD_ID))
 $(info   OUT_DIR=$(OUT_DIR))
diff --git a/core/envsetup.mk b/core/envsetup.mk
index c76e9a6..ecfca9f 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -52,12 +52,11 @@
 # BUILD_OS is the real host doing the build.
 BUILD_OS := $(HOST_OS)
 
-# Under Linux, if USE_MINGW is set, we change HOST_OS to Windows to build the
-# Windows SDK. Only a subset of tools and SDK will manage to build properly.
+HOST_CROSS_OS :=
+# We can cross-build Windows binaries on Linux
 ifeq ($(HOST_OS),linux)
-ifdef USE_MINGW
-  HOST_OS := windows
-endif
+HOST_CROSS_OS := windows
+HOST_CROSS_ARCH := x86
 endif
 
 ifeq ($(HOST_OS),)
@@ -128,11 +127,6 @@
 $(error must be empty or one of: eng user userdebug)
 endif
 
-ifdef USE_MINGW
-# We only build sdk host tools in the MinGW windows build.
-# Build it as 32-bit as well.
-HOST_PREFER_32_BIT := true
-endif
 SDK_HOST_ARCH := x86
 
 # Boards may be defined under $(SRC_TARGET_DIR)/board/$(TARGET_DEVICE)
@@ -213,8 +207,12 @@
 HOST_OUT_release := $(HOST_OUT_ROOT_release)/$(HOST_OS)-$(HOST_PREBUILT_ARCH)
 HOST_OUT_debug := $(HOST_OUT_ROOT_debug)/$(HOST_OS)-$(HOST_PREBUILT_ARCH)
 HOST_OUT := $(HOST_OUT_$(HOST_BUILD_TYPE))
+# TODO: remove
+BUILD_OUT := $(HOST_OUT)
 
-BUILD_OUT := $(OUT_DIR)/host/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)
+HOST_CROSS_OUT_release := $(HOST_OUT_ROOT_release)/windows-$(HOST_PREBUILT_ARCH)
+HOST_CROSS_OUT_debug := $(HOST_OUT_ROOT_debug)/windows-$(HOST_PREBUILT_ARCH)
+HOST_CROSS_OUT := $(HOST_CROSS_OUT_$(HOST_BUILD_TYPE))
 
 TARGET_PRODUCT_OUT_ROOT := $(TARGET_OUT_ROOT)/product
 
@@ -232,6 +230,9 @@
 HOST_OUT_JAVA_LIBRARIES := $(HOST_OUT)/framework
 HOST_OUT_SDK_ADDON := $(HOST_OUT)/sdk_addon
 
+HOST_CROSS_OUT_EXECUTABLES := $(HOST_CROSS_OUT)/bin
+HOST_CROSS_OUT_SHARED_LIBRARIES := $(HOST_CROSS_OUT)/lib
+
 HOST_OUT_INTERMEDIATES := $(HOST_OUT)/obj
 HOST_OUT_HEADERS := $(HOST_OUT_INTERMEDIATES)/include
 HOST_OUT_INTERMEDIATE_LIBRARIES := $(HOST_OUT_INTERMEDIATES)/lib
@@ -239,9 +240,16 @@
 HOST_OUT_COMMON_INTERMEDIATES := $(HOST_COMMON_OUT_ROOT)/obj
 HOST_OUT_FAKE := $(HOST_OUT)/fake_packages
 
+HOST_CROSS_OUT_INTERMEDIATES := $(HOST_CROSS_OUT)/obj
+HOST_CROSS_OUT_HEADERS := $(HOST_CROSS_OUT_INTERMEDIATES)/include
+HOST_CROSS_OUT_INTERMEDIATE_LIBRARIES := $(HOST_CROSS_OUT_INTERMEDIATES)/lib
+HOST_CROSS_OUT_NOTICE_FILES := $(HOST_CROSS_OUT_INTERMEDIATES)/NOTICE_FILES
+
 HOST_OUT_GEN := $(HOST_OUT)/gen
 HOST_OUT_COMMON_GEN := $(HOST_COMMON_OUT_ROOT)/gen
 
+HOST_CROSS_OUT_GEN := $(HOST_CROSS_OUT)/gen
+
 # Out for HOST_2ND_ARCH
 HOST_2ND_ARCH_VAR_PREFIX := 2ND_
 HOST_2ND_ARCH_MODULE_SUFFIX := _32
diff --git a/core/host_executable.mk b/core/host_executable.mk
index 5601b01..bc55ef9 100644
--- a/core/host_executable.mk
+++ b/core/host_executable.mk
@@ -1,5 +1,6 @@
 LOCAL_IS_HOST_MODULE := true
 my_prefix := HOST_
+LOCAL_HOST_PREFIX :=
 include $(BUILD_SYSTEM)/multilib.mk
 
 ifndef LOCAL_MODULE_HOST_ARCH
@@ -50,5 +51,30 @@
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 endif  # HOST_2ND_ARCH
 
+ifdef HOST_CROSS_OS
+my_prefix := HOST_CROSS_
+LOCAL_HOST_PREFIX := $(my_prefix)
+include $(BUILD_SYSTEM)/module_arch_supported.mk
+ifeq ($(my_module_arch_supported),true)
+# Build for Windows
+OVERRIDE_BUILT_MODULE_PATH :=
+# we don't want others using the cross compiled version
+saved_LOCAL_BUILT_MODULE := $(LOCAL_BUILT_MODULE)
+saved_LOCAL_INSTALLED_MODULE := $(LOCAL_INSTALLED_MODULE)
+LOCAL_BUILT_MODULE :=
+LOCAL_INSTALLED_MODULE :=
+LOCAL_INTERMEDIATE_TARGETS :=
+
+ifeq ($(LOCAL_NO_FPIE),)
+LOCAL_LDFLAGS += $(HOST_CROSS_FPIE_FLAGS)
+endif
+
+include $(BUILD_SYSTEM)/host_executable_internal.mk
+LOCAL_BUILT_MODULE := $(saved_LOCAL_BUILT_MODULE)
+LOCAL_INSTALLED_MODULE := $(saved_LOCAL_INSTALLED_MODULE)
+endif
+LOCAL_HOST_PREFIX :=
+endif
+
 LOCAL_NO_2ND_ARCH_MODULE_SUFFIX :=
 my_module_arch_supported :=
diff --git a/core/host_executable_internal.mk b/core/host_executable_internal.mk
index c59f151..b682ffd 100644
--- a/core/host_executable_internal.mk
+++ b/core/host_executable_internal.mk
@@ -9,7 +9,7 @@
 LOCAL_MODULE_CLASS := EXECUTABLES
 endif
 ifeq ($(strip $(LOCAL_MODULE_SUFFIX)),)
-LOCAL_MODULE_SUFFIX := $(HOST_EXECUTABLE_SUFFIX)
+LOCAL_MODULE_SUFFIX := $($(my_prefix)EXECUTABLE_SUFFIX)
 endif
 
 $(call host-executable-hook)
@@ -26,7 +26,7 @@
 
 include $(BUILD_SYSTEM)/binary.mk
 
-my_host_libprofile_rt := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_LIBPROFILE_RT)
+my_host_libprofile_rt := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)LIBPROFILE_RT)
 $(LOCAL_BUILT_MODULE): PRIVATE_HOST_LIBPROFILE_RT := $(my_host_libprofile_rt)
 
 $(LOCAL_BUILT_MODULE): $(all_objects) $(all_libraries)
diff --git a/core/host_shared_library.mk b/core/host_shared_library.mk
index 6964cc9..49000a4 100644
--- a/core/host_shared_library.mk
+++ b/core/host_shared_library.mk
@@ -1,5 +1,6 @@
 LOCAL_IS_HOST_MODULE := true
 my_prefix := HOST_
+LOCAL_HOST_PREFIX :=
 include $(BUILD_SYSTEM)/multilib.mk
 
 ifndef LOCAL_MODULE_HOST_ARCH
@@ -35,6 +36,26 @@
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 endif  # HOST_2ND_ARCH
 
+ifdef HOST_CROSS_OS
+my_prefix := HOST_CROSS_
+LOCAL_HOST_PREFIX := $(my_prefix)
+include $(BUILD_SYSTEM)/module_arch_supported.mk
+ifeq ($(my_module_arch_supported),true)
+# Build for Windows
+OVERRIDE_BUILT_MODULE_PATH :=
+LOCAL_BUILT_MODULE :=
+LOCAL_MODULE_SUFFIX :=
+# We don't want makefiles using the cross-compiled host tool
+saved_LOCAL_INSTALLED_MODULE := $(LOCAL_INSTALLED_MODULE)
+LOCAL_INSTALLED_MODULE :=
+LOCAL_INTERMEDIATE_TARGETS :=
+
+include $(BUILD_SYSTEM)/host_shared_library_internal.mk
+LOCAL_INSTALLED_MODULE := $(saved_LOCAL_INSTALLED_MODULE)
+endif
+LOCAL_HOST_PREFIX :=
+endif
+
 my_module_arch_supported :=
 
 ###########################################################
diff --git a/core/host_shared_library_internal.mk b/core/host_shared_library_internal.mk
index 9da778a..740c941 100644
--- a/core/host_shared_library_internal.mk
+++ b/core/host_shared_library_internal.mk
@@ -11,7 +11,7 @@
 LOCAL_MODULE_CLASS := SHARED_LIBRARIES
 endif
 ifeq ($(strip $(LOCAL_MODULE_SUFFIX)),)
-LOCAL_MODULE_SUFFIX := $(HOST_SHLIB_SUFFIX)
+LOCAL_MODULE_SUFFIX := $($(my_prefix)SHLIB_SUFFIX)
 endif
 ifneq ($(strip $(OVERRIDE_BUILT_MODULE_PATH)),)
 $(error $(LOCAL_PATH): Illegal use of OVERRIDE_BUILT_MODULE_PATH)
@@ -34,11 +34,11 @@
 
 # Put the built modules of all shared libraries in a common directory
 # to simplify the link line.
-OVERRIDE_BUILT_MODULE_PATH := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_OUT_INTERMEDIATE_LIBRARIES)
+OVERRIDE_BUILT_MODULE_PATH := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)OUT_INTERMEDIATE_LIBRARIES)
 
 include $(BUILD_SYSTEM)/binary.mk
 
-my_host_libprofile_rt := $($(LOCAL_2ND_ARCH_VAR_PREFIX)HOST_LIBPROFILE_RT)
+my_host_libprofile_rt := $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)LIBPROFILE_RT)
 $(LOCAL_BUILD_MODULE): PRIVATE_HOST_LIBPROFILE_RT := $(my_host_libprofile_rt)
 
 $(LOCAL_BUILT_MODULE): \
diff --git a/core/host_static_library.mk b/core/host_static_library.mk
index dd7462d..aa8c0e3 100644
--- a/core/host_static_library.mk
+++ b/core/host_static_library.mk
@@ -1,5 +1,6 @@
 LOCAL_IS_HOST_MODULE := true
 my_prefix := HOST_
+LOCAL_HOST_PREFIX :=
 include $(BUILD_SYSTEM)/multilib.mk
 
 ifndef LOCAL_MODULE_HOST_ARCH
@@ -35,6 +36,22 @@
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 endif  # HOST_2ND_ARCH
 
+ifdef HOST_CROSS_OS
+my_prefix := HOST_CROSS_
+LOCAL_HOST_PREFIX := $(my_prefix)
+include $(BUILD_SYSTEM)/module_arch_supported.mk
+ifeq ($(my_module_arch_supported),true)
+# Build for Windows
+OVERRIDE_BUILT_MODULE_PATH :=
+LOCAL_BUILT_MODULE :=
+LOCAL_INSTALLED_MODULE :=
+LOCAL_INTERMEDIATE_TARGETS :=
+
+include $(BUILD_SYSTEM)/host_static_library_internal.mk
+endif
+LOCAL_HOST_PREFIX :=
+endif
+
 my_module_arch_supported :=
 
 ###########################################################
diff --git a/core/main.mk b/core/main.mk
index 9ae3086..def86f5 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -449,16 +449,6 @@
 $(INTERNAL_MODIFIER_TARGETS): $(DEFAULT_GOAL)
 endif
 
-# Bring in all modules that need to be built.
-ifeq ($(HOST_OS),windows)
-SDK_ONLY := true
-endif
-
-ifeq ($(SDK_ONLY),true)
-include $(TOPDIR)sdk/build/windows_sdk_whitelist.mk
-include $(TOPDIR)development/build/windows_sdk_whitelist.mk
-
-else	# !SDK_ONLY
 #
 # Typical build; include any Android.mk files we can find.
 #
@@ -466,8 +456,6 @@
 
 FULL_BUILD := true
 
-endif	# !SDK_ONLY
-
 # Before we go and include all of the module makefiles, stash away
 # the PRODUCT_* values so that later we can verify they are not modified.
 stash_product_vars:=true
@@ -579,6 +567,8 @@
     $(m))))
 endef
 
+# If a module is for a cross host os, the required modules must be for
+# that OS too.
 # If a module is built for 32-bit, the required modules must be 32-bit too;
 # Otherwise if the module is an exectuable or shared library,
 #   the required modules must be 64-bit;
@@ -586,6 +576,8 @@
 $(foreach m,$(ALL_MODULES),\
   $(eval r := $(ALL_MODULES.$(m).REQUIRED))\
   $(if $(r),\
+    $(if $(ALL_MODULES.$(m).FOR_HOST_CROSS),\
+      $(eval r := $(addprefix host_cross_,$(r))))\
     $(if $(ALL_MODULES.$(m).FOR_2ND_ARCH),\
       $(eval r_r := $(call get-32-bit-modules-if-we-can,$(r))),\
       $(if $(filter EXECUTABLES SHARED_LIBRARIES,$(ALL_MODULES.$(m).CLASS)),\
@@ -608,32 +600,40 @@
     $(eval r := $(call module-installed-files,$(r))) \
     $(eval t_m := $(filter $(TARGET_OUT_ROOT)/%, $(ALL_MODULES.$(m).INSTALLED))) \
     $(eval h_m := $(filter $(HOST_OUT_ROOT)/%, $(ALL_MODULES.$(m).INSTALLED))) \
+    $(eval hc_m := $(filter $(HOST_CROSS_OUT_ROOT)/%, $(ALL_MODULES.$(m).INSTALLED))) \
     $(eval t_r := $(filter $(TARGET_OUT_ROOT)/%, $(r))) \
     $(eval h_r := $(filter $(HOST_OUT_ROOT)/%, $(r))) \
+    $(eval hc_r := $(filter $(HOST_CROSS_OUT_ROOT)/%, $(r))) \
     $(eval t_m := $(filter-out $(t_r), $(t_m))) \
     $(eval h_m := $(filter-out $(h_r), $(h_m))) \
+    $(eval hc_m := $(filter-out $(hc_r), $(hc_m))) \
     $(if $(t_m), $(eval $(call add-required-deps, $(t_m),$(t_r)))) \
     $(if $(h_m), $(eval $(call add-required-deps, $(h_m),$(h_r)))) \
+    $(if $(hc_m), $(eval $(call add-required-deps, $(hc_m),$(hc_r)))) \
    ) \
  )
 
 t_m :=
 h_m :=
+hc_m :=
 t_r :=
 h_r :=
+hc_r :=
 
 # Establish the dependecies on the shared libraries.
 # It also adds the shared library module names to ALL_MODULES.$(m).REQUIRED,
 # so they can be expanded to product_MODULES later.
-# $(1): TARGET_ or HOST_.
+# $(1): TARGET_ or HOST_ or HOST_CROSS_.
 # $(2): non-empty for 2nd arch.
+# $(3): non-empty for host cross compile.
 define resolve-shared-libs-depes
 $(foreach m,$($(if $(2),$($(1)2ND_ARCH_VAR_PREFIX))$(1)DEPENDENCIES_ON_SHARED_LIBRARIES),\
   $(eval p := $(subst :,$(space),$(m)))\
   $(eval mod := $(firstword $(p)))\
   $(eval deps := $(subst $(comma),$(space),$(lastword $(p))))\
   $(if $(2),$(eval deps := $(addsuffix $($(1)2ND_ARCH_MODULE_SUFFIX),$(deps))))\
-  $(eval r := $(filter $($(1)OUT_ROOT)/%,$(call module-installed-files,\
+  $(if $(3),$(eval deps := $(addprefix host_cross_,$(deps))))\
+  $(eval r := $(filter $($(1)OUT)/%,$(call module-installed-files,\
     $(deps))))\
   $(eval $(call add-required-deps,$(word 2,$(p)),$(r)))\
   $(eval ALL_MODULES.$(mod).REQUIRED += $(deps)))
@@ -647,6 +647,9 @@
 ifdef HOST_2ND_ARCH
 $(call resolve-shared-libs-depes,HOST_,true)
 endif
+ifdef HOST_CROSS_OS
+$(call resolve-shared-libs-depes,HOST_CROSS_,,true)
+endif
 
 m :=
 r :=
diff --git a/core/multilib.mk b/core/multilib.mk
index e0615b2..a3ced65 100644
--- a/core/multilib.mk
+++ b/core/multilib.mk
@@ -13,11 +13,3 @@
 $(error $(LOCAL_PATH): Invalid LOCAL_MULTILIB specified for module $(LOCAL_MODULE))
 endif
 endif # my_module_multilib defined
-
-# Windows is a special case. Linux and Darwin are both multilib builds, but we
-# don't have a 64-bit Windows build, so make sure it's not a multilib build.
-ifdef LOCAL_IS_HOST_MODULE
-ifeq ($(HOST_OS),windows)
-my_module_multilib := 32
-endif
-endif
diff --git a/core/ninja.mk b/core/ninja.mk
index 4925493..6d75877 100644
--- a/core/ninja.mk
+++ b/core/ninja.mk
@@ -2,16 +2,67 @@
 
 KATI_OUTPUT_PATTERNS := $(PRODUCT_OUT)/build%.ninja $(PRODUCT_OUT)/ninja%.sh
 NINJA_GOALS := fastincremental generateonly droid showcommands
+# A list of goals which affect parsing of make.
+PARSE_TIME_MAKE_GOALS := \
+	$(PARSE_TIME_MAKE_GOALS) \
+	$(dont_bother_goals) \
+	%tests \
+	APP-% \
+	DUMP_% \
+	ECLIPSE-% \
+	PRODUCT-% \
+	boottarball-nodeps \
+	btnod \
+	build-art% \
+	build_kernel-nodeps \
+	checkbuild \
+	clean-oat% \
+	continuous_instrumentation_tests \
+	continuous_native_tests \
+	cts \
+	custom_images \
+	deps-license \
+	dicttool_aosp \
+	dist \
+	dump-products \
+	dumpvar-% \
+	eng \
+	fusion \
+	oem_image \
+	online-system-api-sdk-docs \
+	pdk \
+	platform \
+	platform-java \
+	product-graph \
+	samplecode \
+	sdk \
+	sdk_addon \
+	sdk_repo \
+	snod \
+	stnod \
+	systemimage-nodeps \
+	systemtarball-nodeps \
+	target-files-package \
+	test-art% \
+	user \
+	userdataimage \
+	userdebug \
+	valgrind-test-art% \
+	win_sdk \
+	winsdk-tools
+
+-include vendor/google/build/ninja_config.mk
 
 ANDROID_TARGETS := $(filter-out $(KATI_OUTPUT_PATTERNS) $(NINJA_GOALS),$(ORIGINAL_MAKECMDGOALS))
+KATI_TARGETS := $(if $(filter $(PARSE_TIME_MAKE_GOALS),$(ANDROID_TARGETS)),$(ANDROID_TARGETS),)
 
 define replace_space_and_slash
 $(subst /,_,$(subst $(space),_,$(sort $1)))
 endef
 
 KATI_NINJA_SUFFIX :=
-ifneq ($(ANDROID_TARGETS),)
-KATI_NINJA_SUFFIX := $(KATI_NINJA_SUFFIX)-$(call replace_space_and_slash,$(ANDROID_TARGETS))
+ifneq ($(KATI_TARGETS),)
+KATI_NINJA_SUFFIX := $(KATI_NINJA_SUFFIX)-$(call replace_space_and_slash,$(KATI_TARGETS))
 endif
 ifneq ($(ONE_SHOT_MAKEFILE),)
 KATI_NINJA_SUFFIX := $(KATI_NINJA_SUFFIX)-mmm-$(call replace_space_and_slash,$(ONE_SHOT_MAKEFILE))
@@ -57,7 +108,7 @@
 kati.intermediate: $(KATI)
 	@echo Running kati to generate build$(KATI_NINJA_SUFFIX).ninja...
 	@#TODO: use separate ninja file for mm or single target build
-	$(hide) $(KATI) --ninja --ninja_dir=$(PRODUCT_OUT) --ninja_suffix=$(KATI_NINJA_SUFFIX) --regen --ignore_dirty=$(OUT_DIR)/% --ignore_optional_include=$(OUT_DIR)/%.P --detect_android_echo --use_find_emulator $(KATI_REMOTE_NUM_JOBS_FLAG) -f build/core/main.mk $(ANDROID_TARGETS) USE_NINJA=false
+	$(hide) $(KATI) --ninja --ninja_dir=$(PRODUCT_OUT) --ninja_suffix=$(KATI_NINJA_SUFFIX) --regen --ignore_dirty=$(OUT_DIR)/% --ignore_optional_include=$(OUT_DIR)/%.P --detect_android_echo --use_find_emulator $(KATI_REMOTE_NUM_JOBS_FLAG) -f build/core/main.mk $(or $(KATI_TARGETS),--gen_all_phony_targets) USE_NINJA=false
 
 KATI_CXX := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_CPPFLAGS)
 KATI_LD := $(CLANG_CXX) $(CLANG_HOST_GLOBAL_LDFLAGS)
diff --git a/core/notice_files.mk b/core/notice_files.mk
index 43a5435..cf2dad6 100644
--- a/core/notice_files.mk
+++ b/core/notice_files.mk
@@ -14,6 +14,7 @@
 # so my_prefix is not set at this point.
 ifeq ($(LOCAL_IS_HOST_MODULE),true)
   my_prefix := HOST_
+  LOCAL_HOST_PREFIX :=
 else
   my_prefix := TARGET_
 endif
@@ -56,6 +57,7 @@
 
 # In case it's actually a host file
 module_installed_filename := $(patsubst $(HOST_OUT)%,%,$(module_installed_filename))
+module_installed_filename := $(patsubst $(HOST_CROSS_OUT)%,%,$(module_installed_filename))
 
 installed_notice_file := $($(my_prefix)OUT_NOTICE_FILES)/src/$(module_installed_filename).txt
 
diff --git a/core/prebuilt.mk b/core/prebuilt.mk
index d3f9d1a..ed25f71 100644
--- a/core/prebuilt.mk
+++ b/core/prebuilt.mk
@@ -8,6 +8,7 @@
 
 ifdef LOCAL_IS_HOST_MODULE
   my_prefix := HOST_
+  LOCAL_HOST_PREFIX :=
 else
   my_prefix := TARGET_
 endif
@@ -52,4 +53,26 @@
 
 LOCAL_2ND_ARCH_VAR_PREFIX :=
 
+ifdef LOCAL_IS_HOST_MODULE
+ifdef HOST_CROSS_OS
+ifneq (,$(filter EXECUTABLES STATIC_LIBRARIES SHARED_LIBRARIES,$(LOCAL_MODULE_CLASS)))
+my_prefix := HOST_CROSS_
+LOCAL_HOST_PREFIX := $(my_prefix)
+include $(BUILD_SYSTEM)/module_arch_supported.mk
+ifeq ($(my_module_arch_supported),true)
+# host cross compilation is supported
+OVERRIDE_BUILT_MODULE_PATH :=
+LOCAL_BUILT_MODULE :=
+LOCAL_INSTALLED_MODULE :=
+LOCAL_MODULE_STEM :=
+LOCAL_BUILT_MODULE_STEM :=
+LOCAL_INSTALLED_MODULE_STEM :=
+LOCAL_INTERMEDIATE_TARGETS :=
+include $(BUILD_SYSTEM)/prebuilt_internal.mk
+endif
+LOCAL_HOST_PREFIX :=
+endif
+endif
+endif
+
 my_module_arch_supported :=
diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index 1225b61..42007eb 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -128,10 +128,10 @@
     # verification if it has non-zero contents in the padding bytes.
     # Bug: 23828506
     if padded:
-      self.clobbered_blocks = RangeSet(
-          data=(self.total_blocks-1, self.total_blocks))
+      clobbered_blocks = [self.total_blocks-1, self.total_blocks]
     else:
-      self.clobbered_blocks = RangeSet()
+      clobbered_blocks = []
+    self.clobbered_blocks = clobbered_blocks
     self.extended = RangeSet()
 
     zero_blocks = []
@@ -147,11 +147,15 @@
         nonzero_blocks.append(i)
         nonzero_blocks.append(i+1)
 
-    self.file_map = {"__ZERO": RangeSet(zero_blocks),
-                     "__NONZERO": RangeSet(nonzero_blocks)}
+    assert zero_blocks or nonzero_blocks or clobbered_blocks
 
-    if self.clobbered_blocks:
-      self.file_map["__COPY"] = self.clobbered_blocks
+    self.file_map = dict()
+    if zero_blocks:
+      self.file_map["__ZERO"] = RangeSet(data=zero_blocks)
+    if nonzero_blocks:
+      self.file_map["__NONZERO"] = RangeSet(data=nonzero_blocks)
+    if clobbered_blocks:
+      self.file_map["__COPY"] = RangeSet(data=clobbered_blocks)
 
   def ReadRangeSet(self, ranges):
     return [self.data[s*self.blocksize:e*self.blocksize] for (s, e) in ranges]
@@ -507,6 +511,7 @@
     # Zero out extended blocks as a workaround for bug 20881595.
     if self.tgt.extended:
       out.append("zero %s\n" % (self.tgt.extended.to_string_raw(),))
+      total += self.tgt.extended.size()
 
     # We erase all the blocks on the partition that a) don't contain useful
     # data in the new image and b) will not be touched by dm-verity.
@@ -517,7 +522,7 @@
       out.append("erase %s\n" % (new_dontcare.to_string_raw(),))
 
     out.insert(0, "%d\n" % (self.version,))   # format version number
-    out.insert(1, str(total) + "\n")
+    out.insert(1, "%d\n" % (total,))
     if self.version >= 2:
       # version 2 only: after the total block count, we give the number
       # of stash slots needed, and the maximum size needed (in blocks)