diff --git a/build/Android.executable.mk b/build/Android.executable.mk
index 3b2d1cc..f543a19 100644
--- a/build/Android.executable.mk
+++ b/build/Android.executable.mk
@@ -201,6 +201,9 @@
 # $(5): library dependencies (host only)
 # $(6): extra include directories
 # $(7): multilib (default: empty), valid values: {,32,64,both})
+# $(8): host prefer 32-bit: {true, false} (default: false).  If argument
+#       `multilib` is explicitly set to 64, ignore the "host prefer 32-bit"
+#       setting and only build a 64-bit executable on host.
 define build-art-multi-executable
   $(foreach debug_flavor,ndebug debug,
     $(foreach target_flavor,host target,
@@ -211,6 +214,7 @@
       art-multi-lib-dependencies-host := $(5)
       art-multi-include-extra := $(6)
       art-multi-multilib := $(7)
+      art-multi-host-prefer-32-bit := $(8)
 
       # Add either -host or -target specific lib dependencies to the lib dependencies.
       art-multi-lib-dependencies += $$(art-multi-lib-dependencies-$(target_flavor))
@@ -223,6 +227,14 @@
       # Build the env guard var name, e.g. ART_BUILD_HOST_NDEBUG.
       art-multi-env-guard := $$(call art-string-to-uppercase,ART_BUILD_$(target_flavor)_$(debug_flavor))
 
+      ifeq ($(target_flavor),host)
+        ifeq ($$($$(art-multi-host-prefer-32-bit)),true)
+          ifneq ($$($$(art-multi-multilib)),64)
+            art-multi-multilib := 32
+          endif
+        endif
+      endif
+
       # Build the art executable only if the corresponding env guard was set.
       ifeq ($$($$(art-multi-env-guard)),true)
         $$(eval $$(call build-art-executable,$$(art-multi-binary-name),$$(art-multi-source-files),$$(art-multi-lib-dependencies),$$(art-multi-include-extra),$(target_flavor),$(debug_flavor),$$(art-multi-multilib)))
@@ -236,6 +248,7 @@
       art-multi-lib-dependencies-host :=
       art-multi-include-extra :=
       art-multi-multilib :=
+      art-multi-host-prefer-32-bit :=
       art-multi-env-guard :=
     )
   )
diff --git a/dex2oat/Android.mk b/dex2oat/Android.mk
index e252765..f10acf9 100644
--- a/dex2oat/Android.mk
+++ b/dex2oat/Android.mk
@@ -38,9 +38,10 @@
   dex2oat_target_arch := 32
 endif
 
-# We need to explcitly give the arch, as giving 'both' will make the
-# build-art-executable rule compile dex2oat for 64bits.
 ifeq ($(HOST_PREFER_32_BIT),true)
+  # We need to explicitly restrict the host arch to 32-bit only, as
+  # giving 'both' would make build-art-executable generate a build
+  # rule for a 64-bit dex2oat executable too.
   dex2oat_host_arch := 32
 else
   dex2oat_host_arch := both
@@ -71,4 +72,8 @@
   endif
 endif
 
+# Clear locals now they've served their purpose.
+dex2oat_target_arch :=
+dex2oat_host_arch :=
+
 endif
diff --git a/imgdiag/Android.mk b/imgdiag/Android.mk
index d5d7c22..83315be 100644
--- a/imgdiag/Android.mk
+++ b/imgdiag/Android.mk
@@ -25,4 +25,8 @@
 # that the image it's analyzing be the same ISA as the runtime ISA.
 
 # Build variants {target,host} x {debug,ndebug} x {32,64}
-$(eval $(call build-art-multi-executable,imgdiag,$(IMGDIAG_SRC_FILES),libart-compiler libbacktrace,libcutils,libziparchive-host,art/compiler,both))
+#
+# Honor HOST_PREFER_32_BIT, as building a 64-bit imgdiag executable
+# when HOST_PREFER_32_BIT is true would require an unmet dependency on
+# 64-bit libbacktrace.
+$(eval $(call build-art-multi-executable,imgdiag,$(IMGDIAG_SRC_FILES),libart-compiler libbacktrace,libcutils,libziparchive-host,art/compiler,both,$(HOST_PREFER_32_BIT)))