diff --git a/core/clang/mips.mk b/core/clang/mips.mk
index 1624b6f..08daf40 100644
--- a/core/clang/mips.mk
+++ b/core/clang/mips.mk
@@ -7,14 +7,6 @@
 # Include common unknown flags
 CLANG_CONFIG_mips_UNKNOWN_CFLAGS := \
   $(CLANG_CONFIG_UNKNOWN_CFLAGS) \
-  -mips32 \
-  -mips32r2 \
-  -mips32r6 \
-  -mfp32 \
-  -mfp64 \
-  -mfpxx \
-  -modd-spreg \
-  -mno-odd-spreg \
   -fno-strict-volatile-bitfields \
   -fgcse-after-reload \
   -frerun-cse-after-loop \
diff --git a/core/clang/mips64.mk b/core/clang/mips64.mk
index a76aa08..612175c 100644
--- a/core/clang/mips64.mk
+++ b/core/clang/mips64.mk
@@ -7,7 +7,6 @@
 # Include common unknown flags
 CLANG_CONFIG_mips64_UNKNOWN_CFLAGS := \
   $(CLANG_CONFIG_UNKNOWN_CFLAGS) \
-  -mips64r6 \
   -fno-strict-volatile-bitfields \
   -fgcse-after-reload \
   -frerun-cse-after-loop \
diff --git a/core/envsetup.mk b/core/envsetup.mk
index a57041b..efcad0d 100644
--- a/core/envsetup.mk
+++ b/core/envsetup.mk
@@ -67,13 +67,6 @@
 $(error Unable to determine HOST_OS from uname -sm: $(UNAME)!)
 endif
 
-# TODO: Replace BUILD_HOST_64bit with a flag that forces 32-bit build,
-# after we default to 64-bit host build.
-ifeq (,$(BUILD_HOST_64bit))
-# Default to 32-bit-by-default multilib host build.
-HOST_PREFER_32_BIT := true
-endif
-
 # HOST_ARCH
 ifneq (,$(findstring x86_64,$(UNAME)))
   HOST_ARCH := x86_64
@@ -81,12 +74,6 @@
   HOST_IS_64_BIT := true
 endif
 
-ifeq ($(HOST_PREFER_32_BIT),true)
-SDK_HOST_ARCH := x86
-else
-SDK_HOST_ARCH := $(HOST_ARCH)
-endif
-
 BUILD_ARCH := $(HOST_ARCH)
 BUILD_2ND_ARCH := $(HOST_2ND_ARCH)
 
@@ -133,6 +120,17 @@
 $(error must be empty or one of: eng user userdebug)
 endif
 
+# Build host as 32-bit for SDK build.
+ifneq ($(filter $(MAKECMDGOALS),win_sdk sdk),)
+HOST_PREFER_32_BIT := true
+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)
 # or under vendor/*/$(TARGET_DEVICE).  Search in both places, but
 # make sure only one exists.