diff --git a/core/config.mk b/core/config.mk
index 3e527a8..51810aa 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -675,8 +675,12 @@
 # Set up RS prebuilt variables for compatibility library
 
 RS_PREBUILT_CLCORE := prebuilts/sdk/renderscript/lib/$(TARGET_ARCH)/librsrt_$(TARGET_ARCH).bc
-RS_PREBUILT_LIBPATH := -L prebuilts/ndk/8/platforms/android-9/arch-$(TARGET_ARCH)/usr/lib
 RS_PREBUILT_COMPILER_RT := prebuilts/sdk/renderscript/lib/$(TARGET_ARCH)/libcompiler_rt.a
+ifeq (true,$(TARGET_IS_64_BIT))
+RS_PREBUILT_LIBPATH := -L prebuilts/ndk/9/platforms/android-21/arch-$(TARGET_ARCH)/usr/lib
+else
+RS_PREBUILT_LIBPATH := -L prebuilts/ndk/8/platforms/android-9/arch-$(TARGET_ARCH)/usr/lib
+endif
 
 # API Level lists for Renderscript Compat lib.
 RSCOMPAT_32BIT_ONLY_API_LEVELS := 8 9 10 11 12 13 14 15 16 17 18 19 20
diff --git a/core/java.mk b/core/java.mk
index 0ff59fc..040e674 100644
--- a/core/java.mk
+++ b/core/java.mk
@@ -148,19 +148,27 @@
 RenderScript_file_stamp := $(LOCAL_INTERMEDIATE_SOURCE_DIR)/RenderScript.stamp
 renderscript_intermediate.COMMON := $(LOCAL_INTERMEDIATE_SOURCE_DIR)/renderscript
 
+# Defaulting to an empty string uses the latest available platform SDK.
 renderscript_target_api :=
 
 ifneq (,$(LOCAL_RENDERSCRIPT_TARGET_API))
-renderscript_target_api := $(LOCAL_RENDERSCRIPT_TARGET_API)
+  renderscript_target_api := $(LOCAL_RENDERSCRIPT_TARGET_API)
 else
-ifneq (,$(LOCAL_SDK_VERSION))
-# Set target-api for LOCAL_SDK_VERSIONs other than current.
-ifneq (,$(filter-out current system_current, $(LOCAL_SDK_VERSION)))
-renderscript_target_api := $(LOCAL_SDK_VERSION)
-endif
-endif  # LOCAL_SDK_VERSION is set
+  ifneq (,$(LOCAL_SDK_VERSION))
+    # Set target-api for LOCAL_SDK_VERSIONs other than current.
+    ifneq (,$(filter-out current system_current, $(LOCAL_SDK_VERSION)))
+      renderscript_target_api := $(LOCAL_SDK_VERSION)
+    endif
+  endif  # LOCAL_SDK_VERSION is set
 endif  # LOCAL_RENDERSCRIPT_TARGET_API is set
 
+# For 64-bit, we always have to upgrade to at least 21
+ifeq ($(TARGET_IS_64_BIT),true)
+  ifneq ($(filter $(RSCOMPAT_32BIT_ONLY_API_LEVELS),$(renderscript_target_api)),)
+    renderscript_target_api := 21
+  endif
+endif
+
 ifeq ($(LOCAL_RENDERSCRIPT_CC),)
 LOCAL_RENDERSCRIPT_CC := $(LLVM_RS_CC)
 endif