diff --git a/boot/bootutil/include/bootutil/bootutil_log.h b/boot/bootutil/include/bootutil/bootutil_log.h
new file mode 100644
index 0000000..6dca9b3
--- /dev/null
+++ b/boot/bootutil/include/bootutil/bootutil_log.h
@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2017 Linaro Limited
+ *
+ * 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.
+ */
+
+#ifndef H_BOOTUTIL_LOG_H_
+#define H_BOOTUTIL_LOG_H_
+
+#include "ignore.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * When building for targets running Zephyr, delegate to its native
+ * logging subsystem.
+ *
+ * In this case:
+ *
+ * - BOOT_LOG_LEVEL determines SYS_LOG_LEVEL,
+ * - BOOT_LOG_ERR() and friends are SYS_LOG_ERR() etc.
+ * - SYS_LOG_DOMAIN is unconditionally set to "MCUBOOT"
+ */
+#ifdef __ZEPHYR__
+
+#define BOOT_LOG_LEVEL_OFF	SYS_LOG_LEVEL_OFF
+#define BOOT_LOG_LEVEL_ERROR	SYS_LOG_LEVEL_ERROR
+#define BOOT_LOG_LEVEL_WARNING	SYS_LOG_LEVEL_WARNING
+#define BOOT_LOG_LEVEL_INFO	SYS_LOG_LEVEL_INFO
+#define BOOT_LOG_LEVEL_DEBUG	SYS_LOG_LEVEL_DEBUG
+
+/* Treat BOOT_LOG_LEVEL equivalently to SYS_LOG_LEVEL. */
+#ifndef BOOT_LOG_LEVEL
+#define BOOT_LOG_LEVEL CONFIG_SYS_LOG_DEFAULT_LEVEL
+#elif (BOOT_LOG_LEVEL < CONFIG_SYS_LOG_OVERRIDE_LEVEL)
+#undef BOOT_LOG_LEVEL
+#define BOOT_LOG_LEVEL CONFIG_SYS_LOG_OVERRIDE_LEVEL
+#endif
+
+#define SYS_LOG_LEVEL BOOT_LOG_LEVEL
+
+#undef SYS_LOG_DOMAIN
+#define SYS_LOG_DOMAIN "MCUBOOT"
+
+#define BOOT_LOG_ERR(...) SYS_LOG_ERR(__VA_ARGS__)
+#define BOOT_LOG_WRN(...) SYS_LOG_WRN(__VA_ARGS__)
+#define BOOT_LOG_INF(...) SYS_LOG_INF(__VA_ARGS__)
+#define BOOT_LOG_DBG(...) SYS_LOG_DBG(__VA_ARGS__)
+
+#include <logging/sys_log.h>
+
+/*
+ * In other environments, logging calls are no-ops.
+ */
+#else  /* !defined(__ZEPHYR__) */
+
+#define BOOT_LOG_LEVEL_OFF	0
+#define BOOT_LOG_LEVEL_ERROR	1
+#define BOOT_LOG_LEVEL_WARNING	2
+#define BOOT_LOG_LEVEL_INFO	3
+#define BOOT_LOG_LEVEL_DEBUG	4
+
+#define BOOT_LOG_ERR(...) IGNORE(__VA_ARGS__)
+#define BOOT_LOG_WRN(...) IGNORE(__VA_ARGS__)
+#define BOOT_LOG_INF(...) IGNORE(__VA_ARGS__)
+#define BOOT_LOG_DBG(...) IGNORE(__VA_ARGS__)
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/boot/bootutil/include/bootutil/ignore.h b/boot/bootutil/include/bootutil/ignore.h
new file mode 100644
index 0000000..46282a0
--- /dev/null
+++ b/boot/bootutil/include/bootutil/ignore.h
@@ -0,0 +1,64 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.
+ */
+
+#ifndef H_IGNORE_
+#define H_IGNORE_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * These macros prevent the "set but not used" warnings for log writes below
+ * the log level.
+ */
+
+#define IGN_1(X) ((void)(X))
+#define IGN_2(X, ...) ((void)(X));IGN_1(__VA_ARGS__)
+#define IGN_3(X, ...) ((void)(X));IGN_2(__VA_ARGS__)
+#define IGN_4(X, ...) ((void)(X));IGN_3(__VA_ARGS__)
+#define IGN_5(X, ...) ((void)(X));IGN_4(__VA_ARGS__)
+#define IGN_6(X, ...) ((void)(X));IGN_5(__VA_ARGS__)
+#define IGN_7(X, ...) ((void)(X));IGN_6(__VA_ARGS__)
+#define IGN_8(X, ...) ((void)(X));IGN_7(__VA_ARGS__)
+#define IGN_9(X, ...) ((void)(X));IGN_8(__VA_ARGS__)
+#define IGN_10(X, ...) ((void)(X));IGN_9(__VA_ARGS__)
+#define IGN_11(X, ...) ((void)(X));IGN_10(__VA_ARGS__)
+#define IGN_12(X, ...) ((void)(X));IGN_11(__VA_ARGS__)
+#define IGN_13(X, ...) ((void)(X));IGN_12(__VA_ARGS__)
+#define IGN_14(X, ...) ((void)(X));IGN_13(__VA_ARGS__)
+#define IGN_15(X, ...) ((void)(X));IGN_14(__VA_ARGS__)
+#define IGN_16(X, ...) ((void)(X));IGN_15(__VA_ARGS__)
+#define IGN_17(X, ...) ((void)(X));IGN_16(__VA_ARGS__)
+#define IGN_18(X, ...) ((void)(X));IGN_17(__VA_ARGS__)
+#define IGN_19(X, ...) ((void)(X));IGN_18(__VA_ARGS__)
+#define IGN_20(X, ...) ((void)(X));IGN_19(__VA_ARGS__)
+
+#define GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, \
+                  _13, _14, _15, _16, _17, _18, _19, _20, NAME, ...) NAME
+#define IGNORE(...) \
+    GET_MACRO(__VA_ARGS__, IGN_20, IGN_19, IGN_18, IGN_17, IGN_16, IGN_15, \
+              IGN_14, IGN_13, IGN_12, IGN_11, IGN_10, IGN_9, IGN_8, IGN_7, \
+              IGN_6, IGN_5, IGN_4, IGN_3, IGN_2, IGN_1)(__VA_ARGS__)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif