diff --git a/Android.mk b/Android.mk
index 0a9a0b8..295f2c2 100644
--- a/Android.mk
+++ b/Android.mk
@@ -55,23 +55,21 @@
 # "m dalvik-host" for quick minimal host build
 #
 
-ifeq ($(WITH_HOST_DALVIK),true)
-    .PHONY: dalvik-host
-    dalvik-host: \
-        dalvik \
-        $(HOST_OUT)/bin/dalvikvm \
-        $(HOST_OUT)/bin/dexopt \
-        $(HOST_OUT)/lib/libjavacore.so \
-        $(HOST_OUT)/lib/libjavacrypto.so \
-        $(HOST_OUT)/lib/libjavacoretests.so \
-        cacerts-host \
-        core-hostdex \
-        conscrypt-hostdex \
-        okhttp-hostdex \
-        bouncycastle-hostdex \
-        apache-xml-hostdex \
-        apache-harmony-tests-hostdex \
-        $(call intermediates-dir-for,JAVA_LIBRARIES,core-tests,,COMMON)/classes.jar
-endif
+.PHONY: dalvik-host
+dalvik-host: \
+    dalvik \
+    $(HOST_OUT)/bin/dalvikvm \
+    $(HOST_OUT)/bin/dexopt \
+    $(HOST_OUT)/lib/libjavacore.so \
+    $(HOST_OUT)/lib/libjavacrypto.so \
+    $(HOST_OUT)/lib/libjavacoretests.so \
+    cacerts-host \
+    core-hostdex \
+    conscrypt-hostdex \
+    okhttp-hostdex \
+    bouncycastle-hostdex \
+    apache-xml-hostdex \
+    apache-harmony-tests-hostdex \
+    $(call intermediates-dir-for,JAVA_LIBRARIES,core-tests,,COMMON)/classes.jar
 
 include $(subdir_makefiles)
diff --git a/CaCerts.mk b/CaCerts.mk
index 980d0fb..f85f524 100644
--- a/CaCerts.mk
+++ b/CaCerts.mk
@@ -50,10 +50,9 @@
 # This is so that build/target/product/core.mk can use cacerts in PRODUCT_PACKAGES
 ALL_MODULES.cacerts.INSTALLED := $(cacerts_target)
 
-ifeq ($(WITH_HOST_DALVIK),true)
 cacerts_host_directory := $(HOST_OUT)/etc/security/cacerts
 $(foreach cacert, $(cacerts), $(eval $(call include-prebuilt-with-destination-directory,host-cacert-$(notdir $(cacert)),$(cacert),$(cacerts_host_directory))))
-endif
+
 cacerts_host := $(addprefix $(cacerts_host_directory)/,$(foreach cacert,$(cacerts),$(notdir $(cacert))))
 .PHONY: cacerts-host
 cacerts-host: $(cacerts_host)
diff --git a/JavaLibrary.mk b/JavaLibrary.mk
index d97f453..8935b9a 100644
--- a/JavaLibrary.mk
+++ b/JavaLibrary.mk
@@ -167,38 +167,36 @@
 LOCAL_MODULE := dex-host
 include $(BUILD_HOST_JAVA_LIBRARY)
 
-ifeq ($(WITH_HOST_DALVIK),true)
+# Definitions to make the core library.
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := $(libdvm_core_src_files)
+LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
+LOCAL_NO_STANDARD_LIBRARIES := true
+LOCAL_JAVACFLAGS := $(local_javac_flags)
+LOCAL_DX_FLAGS := --core-library
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE := core-hostdex
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
+LOCAL_REQUIRED_MODULES := tzdata-host
+include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
 
-    # Definitions to make the core library.
-    include $(CLEAR_VARS)
-    LOCAL_SRC_FILES := $(libdvm_core_src_files)
-    LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
-    LOCAL_NO_STANDARD_LIBRARIES := true
-    LOCAL_JAVACFLAGS := $(local_javac_flags)
-    LOCAL_DX_FLAGS := --core-library
-    LOCAL_MODULE_TAGS := optional
-    LOCAL_MODULE := core-hostdex
-    LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
-    LOCAL_REQUIRED_MODULES := tzdata-host
-    include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
+include $(CLEAR_VARS)
+LOCAL_SRC_FILES := $(libart_core_src_files)
+LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
+LOCAL_NO_STANDARD_LIBRARIES := true
+LOCAL_JAVACFLAGS := $(local_javac_flags)
+LOCAL_DX_FLAGS := --core-library
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE := core-libart-hostdex
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
+LOCAL_REQUIRED_MODULES := tzdata-host
+# Should not be dex-preopted as it isn't really a Dalvik boot jar or a
+# regular java library, but part of the image for ART.
+LOCAL_DEX_PREOPT := false
+include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
 
-    include $(CLEAR_VARS)
-    LOCAL_SRC_FILES := $(libart_core_src_files)
-    LOCAL_JAVA_RESOURCE_DIRS := $(core_resource_dirs)
-    LOCAL_NO_STANDARD_LIBRARIES := true
-    LOCAL_JAVACFLAGS := $(local_javac_flags)
-    LOCAL_DX_FLAGS := --core-library
-    LOCAL_MODULE_TAGS := optional
-    LOCAL_MODULE := core-libart-hostdex
-    LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
-    LOCAL_REQUIRED_MODULES := tzdata-host
-    # Should not be dex-preopted as it isn't really a Dalvik boot jar or a
-    # regular java library, but part of the image for ART.
-    LOCAL_DEX_PREOPT := false
-    include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
-
-    # Make the core-tests library.
-    ifeq ($(LIBCORE_SKIP_TESTS),)
+# Make the core-tests library.
+ifeq ($(LIBCORE_SKIP_TESTS),)
     include $(CLEAR_VARS)
     LOCAL_SRC_FILES := $(test_src_files)
     LOCAL_JAVA_RESOURCE_DIRS := $(test_resource_dirs)
@@ -209,10 +207,10 @@
     LOCAL_MODULE := core-tests-hostdex
     LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
     include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
-    endif
+endif
 
-    # Make the core-tests-support library.
-    ifeq ($(LIBCORE_SKIP_TESTS),)
+# Make the core-tests-support library.
+ifeq ($(LIBCORE_SKIP_TESTS),)
     include $(CLEAR_VARS)
     LOCAL_SRC_FILES := $(call all-test-java-files-under,support)
     LOCAL_JAVA_RESOURCE_DIRS := $(test_resource_dirs)
@@ -222,7 +220,6 @@
     LOCAL_MODULE := core-tests-support-hostdex
     LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/JavaLibrary.mk
     include $(BUILD_HOST_DALVIK_JAVA_LIBRARY)
-    endif
 endif
 
 #
diff --git a/NativeCode.mk b/NativeCode.mk
index 2a16598..5e149fd 100644
--- a/NativeCode.mk
+++ b/NativeCode.mk
@@ -112,22 +112,21 @@
 # Build for the host.
 #
 
-ifeq ($(WITH_HOST_DALVIK),true)
-    include $(CLEAR_VARS)
-    LOCAL_CLANG := true
-    LOCAL_SRC_FILES += $(core_src_files)
-    LOCAL_CFLAGS += $(core_cflags)
-    LOCAL_C_INCLUDES += $(core_c_includes)
-    LOCAL_CPPFLAGS += $(core_cppflags)
-    LOCAL_LDLIBS += -ldl -lpthread -lrt
-    LOCAL_MODULE_TAGS := optional
-    LOCAL_MODULE := libjavacore
-    LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/NativeCode.mk
-    LOCAL_SHARED_LIBRARIES += $(core_shared_libraries) libexpat-host libicuuc-host libicui18n-host libcrypto-host libz-host
-    LOCAL_STATIC_LIBRARIES += $(core_static_libraries) libziparchive-host libutils
-    include $(BUILD_HOST_SHARED_LIBRARY)
+include $(CLEAR_VARS)
+LOCAL_CLANG := true
+LOCAL_SRC_FILES += $(core_src_files)
+LOCAL_CFLAGS += $(core_cflags)
+LOCAL_C_INCLUDES += $(core_c_includes)
+LOCAL_CPPFLAGS += $(core_cppflags)
+LOCAL_LDLIBS += -ldl -lpthread
+LOCAL_MODULE_TAGS := optional
+LOCAL_MODULE := libjavacore
+LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/NativeCode.mk
+LOCAL_SHARED_LIBRARIES += $(core_shared_libraries) libexpat-host libicuuc-host libicui18n-host libcrypto-host libz-host
+LOCAL_STATIC_LIBRARIES += $(core_static_libraries) libziparchive-host libutils
+include $(BUILD_HOST_SHARED_LIBRARY)
 
-    ifeq ($(LIBCORE_SKIP_TESTS),)
+ifeq ($(LIBCORE_SKIP_TESTS),)
     include $(CLEAR_VARS)
     LOCAL_CLANG := true
     LOCAL_SRC_FILES += $(core_test_files)
@@ -140,5 +139,4 @@
     LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/NativeCode.mk
     LOCAL_SHARED_LIBRARIES := libcrypto-host
     include $(BUILD_HOST_SHARED_LIBRARY)
-    endif # LIBCORE_SKIP_TESTS
-endif
+endif # LIBCORE_SKIP_TESTS
diff --git a/luni/src/main/native/Portability.h b/luni/src/main/native/Portability.h
index 60b7062..fb60ed4 100644
--- a/luni/src/main/native/Portability.h
+++ b/luni/src/main/native/Portability.h
@@ -64,7 +64,6 @@
 // For statfs(3).
 #include <sys/param.h>
 #include <sys/mount.h>
-#define f_frsize f_bsize // TODO: close enough?
 
 #else
 
diff --git a/luni/src/main/native/android_system_OsConstants.cpp b/luni/src/main/native/android_system_OsConstants.cpp
index cc3054a..13a0b1c 100644
--- a/luni/src/main/native/android_system_OsConstants.cpp
+++ b/luni/src/main/native/android_system_OsConstants.cpp
@@ -30,15 +30,19 @@
 #include <stdlib.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
+#ifndef __APPLE__
 #include <sys/prctl.h>
+#endif
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <unistd.h>
 
 // After the others because these are not necessarily self-contained in glibc.
+#ifndef __APPLE__
 #include <linux/if_addr.h>
 #include <linux/rtnetlink.h>
+#endif
 
 #include <net/if.h> // After <sys/socket.h> to work around a Mac header file bug.
 
@@ -229,14 +233,30 @@
 #if defined(IFA_F_DADFAILED)
     initConstant(env, c, "IFA_F_DADFAILED", IFA_F_DADFAILED);
 #endif
+#if defined(IFA_F_DEPRECATED)
     initConstant(env, c, "IFA_F_DEPRECATED", IFA_F_DEPRECATED);
+#endif
+#if defined(IFA_F_HOMEADDRESS)
     initConstant(env, c, "IFA_F_HOMEADDRESS", IFA_F_HOMEADDRESS);
+#endif
+#if defined(IFA_F_NODAD)
     initConstant(env, c, "IFA_F_NODAD", IFA_F_NODAD);
+#endif
+#if defined(IFA_F_OPTIMISTIC)
     initConstant(env, c, "IFA_F_OPTIMISTIC", IFA_F_OPTIMISTIC);
+#endif
+#if defined(IFA_F_PERMANENT)
     initConstant(env, c, "IFA_F_PERMANENT", IFA_F_PERMANENT);
+#endif
+#if defined(IFA_F_SECONDARY)
     initConstant(env, c, "IFA_F_SECONDARY", IFA_F_SECONDARY);
+#endif
+#if defined(IFA_F_TEMPORARY)
     initConstant(env, c, "IFA_F_TEMPORARY", IFA_F_TEMPORARY);
+#endif
+#if defined(IDA_F_TENTATIVE)
     initConstant(env, c, "IFA_F_TENTATIVE", IFA_F_TENTATIVE);
+#endif
     initConstant(env, c, "IFF_ALLMULTI", IFF_ALLMULTI);
 #if defined(IFF_AUTOMEDIA)
     initConstant(env, c, "IFF_AUTOMEDIA", IFF_AUTOMEDIA);
@@ -370,11 +390,21 @@
     initConstant(env, c, "PROT_READ", PROT_READ);
     initConstant(env, c, "PROT_WRITE", PROT_WRITE);
     initConstant(env, c, "R_OK", R_OK);
+#if defined(RT_SCOPE_HOST)
     initConstant(env, c, "RT_SCOPE_HOST", RT_SCOPE_HOST);
+#endif
+#if defined(RT_SCOPE_LINK)
     initConstant(env, c, "RT_SCOPE_LINK", RT_SCOPE_LINK);
+#endif
+#if defined(RT_SCOPE_NOWHERE)
     initConstant(env, c, "RT_SCOPE_NOWHERE", RT_SCOPE_NOWHERE);
+#endif
+#if defined(RT_SCOPE_SITE)
     initConstant(env, c, "RT_SCOPE_SITE", RT_SCOPE_SITE);
+#endif
+#if defined(RT_SCOPE_UNIVERSE)
     initConstant(env, c, "RT_SCOPE_UNIVERSE", RT_SCOPE_UNIVERSE);
+#endif
     initConstant(env, c, "SEEK_CUR", SEEK_CUR);
     initConstant(env, c, "SEEK_END", SEEK_END);
     initConstant(env, c, "SEEK_SET", SEEK_SET);
@@ -441,8 +471,12 @@
     initConstant(env, c, "SO_KEEPALIVE", SO_KEEPALIVE);
     initConstant(env, c, "SO_LINGER", SO_LINGER);
     initConstant(env, c, "SO_OOBINLINE", SO_OOBINLINE);
+#if defined(SO_PASSCRED)
     initConstant(env, c, "SO_PASSCRED", SO_PASSCRED);
+#endif
+#if defined(SO_PEERCRED)
     initConstant(env, c, "SO_PEERCRED", SO_PEERCRED);
+#endif
     initConstant(env, c, "SO_RCVBUF", SO_RCVBUF);
     initConstant(env, c, "SO_RCVLOWAT", SO_RCVLOWAT);
     initConstant(env, c, "SO_RCVTIMEO", SO_RCVTIMEO);
diff --git a/luni/src/main/native/libcore_io_Posix.cpp b/luni/src/main/native/libcore_io_Posix.cpp
index c04f73e..aee3933 100644
--- a/luni/src/main/native/libcore_io_Posix.cpp
+++ b/luni/src/main/native/libcore_io_Posix.cpp
@@ -44,9 +44,14 @@
 #include <stdlib.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
+#ifndef __APPLE__
 #include <sys/prctl.h>
+#endif
 #include <sys/socket.h>
 #include <sys/stat.h>
+#ifdef __APPLE__
+#include <sys/statvfs.h>
+#endif
 #include <sys/syscall.h>
 #include <sys/time.h>
 #include <sys/types.h>
@@ -330,9 +335,14 @@
             static_cast<jlong>(tv.tv_sec), static_cast<jlong>(tv.tv_usec));
 }
 
-static jobject makeStructUcred(JNIEnv* env, const struct ucred& u) {
+static jobject makeStructUcred(JNIEnv* env, const struct ucred& u __unused) {
+#ifdef __APPLE__
+  jniThrowException(env, "java/lang/UnsupportedOperationException", "unimplemented support for ucred on a Mac");
+  return NULL;
+#else
   static jmethodID ctor = env->GetMethodID(JniConstants::structUcredClass, "<init>", "(III)V");
   return env->NewObject(JniConstants::structUcredClass, ctor, u.pid, u.uid, u.gid);
+#endif
 }
 
 static jobject makeStructUtsname(JNIEnv* env, const struct utsname& buf) {
@@ -847,9 +857,19 @@
   return makeStructUcred(env, u);
 }
 
-static jint Posix_gettid(JNIEnv*, jobject) {
+static jint Posix_gettid(JNIEnv* env __unused, jobject) {
+#if defined(__APPLE__)
+  uint64_t owner;
+  int rc = pthread_threadid_np(NULL, &owner);  // Requires Mac OS 10.6
+  if (rc != 0) {
+    throwErrnoException(env, "gettid");
+    return NULL;
+  }
+  return static_cast<jint>(owner);
+#else
   // Neither bionic nor glibc exposes gettid(2).
   return syscall(__NR_gettid);
+#endif
 }
 
 static jint Posix_getuid(JNIEnv*, jobject) {
@@ -1082,19 +1102,31 @@
     return rc;
 }
 
-static void Posix_posix_fallocate(JNIEnv* env, jobject, jobject javaFd, jlong offset, jlong length) {
+static void Posix_posix_fallocate(JNIEnv* env, jobject, jobject javaFd __unused,
+                                  jlong offset __unused, jlong length __unused) {
+#ifdef __APPLE__
+    jniThrowException(env, "java/lang/UnsupportedOperationException",
+                      "fallocate doesn't exist on a Mac");
+#else
     int fd = jniGetFDFromFileDescriptor(env, javaFd);
     errno = TEMP_FAILURE_RETRY(posix_fallocate64(fd, offset, length));
     if (errno != 0) {
         throwErrnoException(env, "posix_fallocate");
     }
+#endif
 }
 
-static jint Posix_prctl(JNIEnv* env, jobject, jint option, jlong arg2, jlong arg3, jlong arg4, jlong arg5) {
+static jint Posix_prctl(JNIEnv* env, jobject, jint option __unused, jlong arg2 __unused,
+                        jlong arg3 __unused, jlong arg4 __unused, jlong arg5 __unused) {
+#ifdef __APPLE__
+    jniThrowException(env, "java/lang/UnsupportedOperationException", "prctl doesn't exist on a Mac");
+    return 0;
+#else
     int result = prctl(static_cast<int>(option),
                        static_cast<unsigned long>(arg2), static_cast<unsigned long>(arg3),
                        static_cast<unsigned long>(arg4), static_cast<unsigned long>(arg5));
     return throwIfMinusOne(env, "prctl", result);
+#endif
 }
 
 static jint Posix_preadBytes(JNIEnv* env, jobject, jobject javaFd, jobject javaBytes, jint byteOffset, jint byteCount, jlong offset) {