diff --git a/adb/Android.mk b/adb/Android.mk
index 0babf1d..7c029be 100644
--- a/adb/Android.mk
+++ b/adb/Android.mk
@@ -63,6 +63,7 @@
     fdevent_test.cpp \
     socket_test.cpp \
     sysdeps_test.cpp \
+    sysdeps/stat_test.cpp \
     transport_test.cpp \
 
 LIBADB_CFLAGS := \
@@ -90,6 +91,7 @@
 
 LIBADB_windows_SRC_FILES := \
     sysdeps_win32.cpp \
+    sysdeps/win32/stat.cpp \
     usb_windows.cpp \
 
 LIBADB_TEST_windows_SRCS := \
diff --git a/adb/adb_utils_test.cpp b/adb/adb_utils_test.cpp
index aabc5d7..4cac485 100644
--- a/adb/adb_utils_test.cpp
+++ b/adb/adb_utils_test.cpp
@@ -52,18 +52,6 @@
 
   ASSERT_TRUE(directory_exists(profiles_dir));
 
-  // On modern (English?) Windows, this is a directory symbolic link to
-  // C:\ProgramData. Symbolic links are rare on Windows and the user requires
-  // a special permission (by default granted to Administrative users) to
-  // create symbolic links.
-  ASSERT_FALSE(directory_exists(subdir(profiles_dir, "All Users")));
-
-  // On modern (English?) Windows, this is a directory junction to
-  // C:\Users\Default. Junctions are used throughout user profile directories
-  // for backwards compatibility and they don't require any special permissions
-  // to create.
-  ASSERT_FALSE(directory_exists(subdir(profiles_dir, "Default User")));
-
   ASSERT_FALSE(directory_exists(subdir(profiles_dir, "does-not-exist")));
 #else
   ASSERT_TRUE(directory_exists("/proc"));
@@ -72,6 +60,28 @@
 #endif
 }
 
+#if defined(_WIN32)
+TEST(adb_utils, directory_exists_win32_symlink_junction) {
+  char profiles_dir[MAX_PATH];
+  DWORD cch = arraysize(profiles_dir);
+
+  // On typical Windows 7, returns C:\Users
+  ASSERT_TRUE(GetProfilesDirectoryA(profiles_dir, &cch));
+
+  // On modern (English?) Windows, this is a directory symbolic link to
+  // C:\ProgramData. Symbolic links are rare on Windows and the user requires
+  // a special permission (by default granted to Administrative users) to
+  // create symbolic links.
+  EXPECT_FALSE(directory_exists(subdir(profiles_dir, "All Users")));
+
+  // On modern (English?) Windows, this is a directory junction to
+  // C:\Users\Default. Junctions are used throughout user profile directories
+  // for backwards compatibility and they don't require any special permissions
+  // to create.
+  EXPECT_FALSE(directory_exists(subdir(profiles_dir, "Default User")));
+}
+#endif
+
 TEST(adb_utils, escape_arg) {
   ASSERT_EQ(R"('')", escape_arg(""));
 
@@ -111,16 +121,22 @@
   EXPECT_EQ("/system/bin", adb_dirname("/system/bin/sh/"));
 }
 
-void test_mkdirs(const std::string basepath) {
+void test_mkdirs(const std::string& basepath) {
   // Test creating a directory hierarchy.
-  EXPECT_TRUE(mkdirs(basepath));
+  ASSERT_TRUE(mkdirs(basepath));
   // Test finding an existing directory hierarchy.
-  EXPECT_TRUE(mkdirs(basepath));
+  ASSERT_TRUE(mkdirs(basepath));
+  // Test mkdirs on an existing hierarchy with a trailing slash.
+  ASSERT_TRUE(mkdirs(basepath + '/'));
+#if defined(_WIN32)
+  ASSERT_TRUE(mkdirs(basepath + '\\'));
+#endif
+
   const std::string filepath = basepath + "/file";
   // Verify that the hierarchy was created by trying to create a file in it.
-  EXPECT_NE(-1, adb_creat(filepath.c_str(), 0600));
+  ASSERT_NE(-1, adb_creat(filepath.c_str(), 0600));
   // If a file exists where we want a directory, the operation should fail.
-  EXPECT_FALSE(mkdirs(filepath));
+  ASSERT_FALSE(mkdirs(filepath));
 }
 
 TEST(adb_utils, mkdirs) {
diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index 477edc1..193b929 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -1275,9 +1275,10 @@
         return hint;
     }
 
-    // If there are any slashes in it, assume it's a relative path;
+    // If any of the OS_PATH_SEPARATORS is found, assume it's a relative path;
     // make it absolute.
-    if (hint.find_first_of(OS_PATH_SEPARATORS) != std::string::npos) {
+    // NOLINT: Do not complain if OS_PATH_SEPARATORS has only one character.
+    if (hint.find_first_of(OS_PATH_SEPARATORS) != std::string::npos) {  // NOLINT
         std::string cwd;
         if (!getcwd(&cwd)) {
             fprintf(stderr, "adb: getcwd failed: %s\n", strerror(errno));
diff --git a/adb/file_sync_client.cpp b/adb/file_sync_client.cpp
index 6a9e163..fbca770 100644
--- a/adb/file_sync_client.cpp
+++ b/adb/file_sync_client.cpp
@@ -433,7 +433,7 @@
 typedef void (sync_ls_cb)(unsigned mode, unsigned size, unsigned time, const char* name);
 
 static bool sync_ls(SyncConnection& sc, const char* path,
-                    std::function<sync_ls_cb> func) {
+                    const std::function<sync_ls_cb>& func) {
     if (!sc.SendRequest(ID_LIST, path)) return false;
 
     while (true) {
diff --git a/adb/sysdeps.h b/adb/sysdeps.h
index 212c1c3..04df16f 100644
--- a/adb/sysdeps.h
+++ b/adb/sysdeps.h
@@ -34,6 +34,8 @@
 #include <android-base/unique_fd.h>
 #include <android-base/utf8.h>
 
+#include "sysdeps/stat.h"
+
 /*
  * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
  * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
@@ -199,8 +201,6 @@
     /* nothing really */
 }
 
-#define  lstat    stat   /* no symlinks on Win32 */
-
 #define  S_ISLNK(m)   0   /* no symlinks on Win32 */
 
 extern int  adb_unlink(const char*  path);
@@ -307,27 +307,6 @@
     return isalpha(path[0]) && path[1] == ':' && path[2] == '\\';
 }
 
-// We later define a macro mapping 'stat' to 'adb_stat'. This causes:
-//   struct stat s;
-//   stat(filename, &s);
-// To turn into the following:
-//   struct adb_stat s;
-//   adb_stat(filename, &s);
-// To get this to work, we need to make 'struct adb_stat' the same as
-// 'struct stat'. Note that this definition of 'struct adb_stat' uses the
-// *current* macro definition of stat, so it may actually be inheriting from
-// struct _stat32i64 (or some other remapping).
-struct adb_stat : public stat {};
-
-static_assert(sizeof(struct adb_stat) == sizeof(struct stat),
-    "structures should be the same");
-
-extern int adb_stat(const char* f, struct adb_stat* s);
-
-// stat is already a macro, undefine it so we can redefine it.
-#undef stat
-#define stat adb_stat
-
 // UTF-8 versions of POSIX APIs.
 extern DIR* adb_opendir(const char* dirname);
 extern struct dirent* adb_readdir(DIR* dir);
diff --git a/adb/sysdeps/stat.h b/adb/sysdeps/stat.h
new file mode 100644
index 0000000..5953595
--- /dev/null
+++ b/adb/sysdeps/stat.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if defined(_WIN32)
+// stat is broken on Win32: stat on a path with a trailing slash or backslash will always fail with
+// ENOENT.
+int adb_stat(const char* path, struct adb_stat* buf);
+
+// We later define a macro mapping 'stat' to 'adb_stat'. This causes:
+//   struct stat s;
+//   stat(filename, &s);
+// To turn into the following:
+//   struct adb_stat s;
+//   adb_stat(filename, &s);
+// To get this to work, we need to make 'struct adb_stat' the same as
+// 'struct stat'. Note that this definition of 'struct adb_stat' uses the
+// *current* macro definition of stat, so it may actually be inheriting from
+// struct _stat32i64 (or some other remapping).
+struct adb_stat : public stat {};
+
+#undef stat
+#define stat adb_stat
+
+// Windows doesn't have lstat.
+#define lstat adb_stat
+
+#endif
diff --git a/adb/sysdeps/stat_test.cpp b/adb/sysdeps/stat_test.cpp
new file mode 100644
index 0000000..2c2e0ee
--- /dev/null
+++ b/adb/sysdeps/stat_test.cpp
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include <string>
+
+#include <android-base/test_utils.h>
+#include <gtest/gtest.h>
+
+#include "adb_utils.h"
+#include "sysdeps.h"
+
+TEST(sysdeps, stat) {
+    TemporaryDir td;
+    TemporaryFile tf;
+
+    struct stat st;
+    ASSERT_EQ(0, stat(td.path, &st));
+    ASSERT_FALSE(S_ISREG(st.st_mode));
+    ASSERT_TRUE(S_ISDIR(st.st_mode));
+
+    ASSERT_EQ(0, stat((std::string(td.path) + '/').c_str(), &st));
+    ASSERT_TRUE(S_ISDIR(st.st_mode));
+
+#if defined(_WIN32)
+    ASSERT_EQ(0, stat((std::string(td.path) + '\\').c_str(), &st));
+    ASSERT_TRUE(S_ISDIR(st.st_mode));
+#endif
+
+    std::string nonexistent_path = std::string(td.path) + "/nonexistent";
+    ASSERT_EQ(-1, stat(nonexistent_path.c_str(), &st));
+    ASSERT_EQ(ENOENT, errno);
+
+    ASSERT_EQ(-1, stat((nonexistent_path + "/").c_str(), &st));
+    ASSERT_EQ(ENOENT, errno);
+
+#if defined(_WIN32)
+    ASSERT_EQ(-1, stat((nonexistent_path + "\\").c_str(), &st));
+    ASSERT_EQ(ENOENT, errno);
+#endif
+
+    ASSERT_EQ(0, stat(tf.path, &st));
+    ASSERT_TRUE(S_ISREG(st.st_mode));
+    ASSERT_FALSE(S_ISDIR(st.st_mode));
+
+    ASSERT_EQ(-1, stat((std::string(tf.path) + '/').c_str(), &st));
+    ASSERT_EQ(ENOTDIR, errno);
+
+#if defined(_WIN32)
+    ASSERT_EQ(-1, stat((std::string(tf.path) + '\\').c_str(), &st));
+    ASSERT_EQ(ENOTDIR, errno);
+#endif
+}
diff --git a/adb/sysdeps/win32/stat.cpp b/adb/sysdeps/win32/stat.cpp
new file mode 100644
index 0000000..844c1ce
--- /dev/null
+++ b/adb/sysdeps/win32/stat.cpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "sysdeps/stat.h"
+
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android-base/utf8.h>
+
+// Version of stat() that takes a UTF-8 path.
+int adb_stat(const char* path, struct adb_stat* s) {
+// This definition of wstat seems to be missing from <sys/stat.h>.
+#if defined(_FILE_OFFSET_BITS) && (_FILE_OFFSET_BITS == 64)
+#ifdef _USE_32BIT_TIME_T
+#define wstat _wstat32i64
+#else
+#define wstat _wstat64
+#endif
+#else
+// <sys/stat.h> has a function prototype for wstat() that should be available.
+#endif
+
+    std::wstring path_wide;
+    if (!android::base::UTF8ToWide(path, &path_wide)) {
+        errno = ENOENT;
+        return -1;
+    }
+
+    // If the path has a trailing slash, stat will fail with ENOENT regardless of whether the path
+    // is a directory or not.
+    bool expected_directory = false;
+    while (*path_wide.rbegin() == u'/' || *path_wide.rbegin() == u'\\') {
+        path_wide.pop_back();
+        expected_directory = true;
+    }
+
+    struct adb_stat st;
+    int result = wstat(path_wide.c_str(), &st);
+    if (result == 0 && expected_directory) {
+        if (!S_ISDIR(st.st_mode)) {
+            errno = ENOTDIR;
+            return -1;
+        }
+    }
+
+    memcpy(s, &st, sizeof(st));
+    return result;
+}
diff --git a/adb/sysdeps_win32.cpp b/adb/sysdeps_win32.cpp
index f94d6fc..ee27406 100644
--- a/adb/sysdeps_win32.cpp
+++ b/adb/sysdeps_win32.cpp
@@ -2252,30 +2252,6 @@
     }
 }
 
-// Version of stat() that takes a UTF-8 path.
-int adb_stat(const char* path, struct adb_stat* s) {
-#pragma push_macro("wstat")
-// This definition of wstat seems to be missing from <sys/stat.h>.
-#if defined(_FILE_OFFSET_BITS) && (_FILE_OFFSET_BITS == 64)
-#ifdef _USE_32BIT_TIME_T
-#define wstat _wstat32i64
-#else
-#define wstat _wstat64
-#endif
-#else
-// <sys/stat.h> has a function prototype for wstat() that should be available.
-#endif
-
-    std::wstring path_wide;
-    if (!android::base::UTF8ToWide(path, &path_wide)) {
-        return -1;
-    }
-
-    return wstat(path_wide.c_str(), s);
-
-#pragma pop_macro("wstat")
-}
-
 // Version of opendir() that takes a UTF-8 path.
 DIR* adb_opendir(const char* path) {
     std::wstring path_wide;
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 665b9d0..dde21d5 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -835,7 +835,7 @@
 }
 
 static void do_for_partition(Transport* transport, const char *part, const char *slot,
-                             std::function<void(const std::string&)> func, bool force_slot) {
+                             const std::function<void(const std::string&)>& func, bool force_slot) {
     std::string has_slot;
     std::string current_slot;
 
@@ -867,7 +867,7 @@
  * partition does not support slots.
  */
 static void do_for_partitions(Transport* transport, const char *part, const char *slot,
-                              std::function<void(const std::string&)> func, bool force_slot) {
+                              const std::function<void(const std::string&)>& func, bool force_slot) {
     std::string has_slot;
 
     if (slot && strcmp(slot, "all") == 0) {
diff --git a/fastboot/socket_test.cpp b/fastboot/socket_test.cpp
index affbdfd..373abc3 100644
--- a/fastboot/socket_test.cpp
+++ b/fastboot/socket_test.cpp
@@ -34,7 +34,7 @@
 // Creates connected sockets |server| and |client|. Returns true on success.
 bool MakeConnectedSockets(Socket::Protocol protocol, std::unique_ptr<Socket>* server,
                           std::unique_ptr<Socket>* client,
-                          const std::string hostname = "localhost") {
+                          const std::string& hostname = "localhost") {
     *server = Socket::NewServer(protocol, 0);
     if (*server == nullptr) {
         ADD_FAILURE() << "Failed to create server.";
diff --git a/init/service.cpp b/init/service.cpp
index f67af2d..44d9d8c 100644
--- a/init/service.cpp
+++ b/init/service.cpp
@@ -850,7 +850,7 @@
     return nullptr;
 }
 
-void ServiceManager::ForEachService(std::function<void(Service*)> callback) const {
+void ServiceManager::ForEachService(const std::function<void(Service*)>& callback) const {
     for (const auto& s : services_) {
         callback(s.get());
     }
diff --git a/init/service.h b/init/service.h
index aa73aaf..fb03a07 100644
--- a/init/service.h
+++ b/init/service.h
@@ -177,7 +177,7 @@
     Service* FindServiceByName(const std::string& name) const;
     Service* FindServiceByPid(pid_t pid) const;
     Service* FindServiceByKeychord(int keychord_id) const;
-    void ForEachService(std::function<void(Service*)> callback) const;
+    void ForEachService(const std::function<void(Service*)>& callback) const;
     void ForEachServiceInClass(const std::string& classname,
                                void (*func)(Service* svc)) const;
     void ForEachServiceWithFlags(unsigned matchflags,
diff --git a/init/util.cpp b/init/util.cpp
index 6c1923f..10ab1c7 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -317,7 +317,7 @@
 }
 
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)> fn) {
+                           const std::function<void(const std::string&, const std::string&, bool)>& fn) {
     std::string cmdline;
     android::base::ReadFileToString("/proc/cmdline", &cmdline);
 
diff --git a/init/util.h b/init/util.h
index 9d522cc..f020da8 100644
--- a/init/util.h
+++ b/init/util.h
@@ -55,7 +55,7 @@
 void remove_link(const char *oldpath, const char *newpath);
 int wait_for_file(const char *filename, int timeout);
 void import_kernel_cmdline(bool in_qemu,
-                           std::function<void(const std::string&, const std::string&, bool)>);
+                           const std::function<void(const std::string&, const std::string&, bool)>&);
 int make_dir(const char *path, mode_t mode);
 int restorecon(const char *pathname);
 int restorecon_recursive(const char *pathname);
diff --git a/libbacktrace/backtrace_offline_test.cpp b/libbacktrace/backtrace_offline_test.cpp
index 88a3533..d6dc2c9 100644
--- a/libbacktrace/backtrace_offline_test.cpp
+++ b/libbacktrace/backtrace_offline_test.cpp
@@ -73,7 +73,7 @@
   return ucontext;
 }
 
-static void OfflineBacktraceFunctionCall(std::function<int(void (*)(void*), void*)> function,
+static void OfflineBacktraceFunctionCall(const std::function<int(void (*)(void*), void*)>& function,
                                          std::vector<uintptr_t>* pc_values) {
   // Create a thread to generate the needed stack and registers information.
   g_exit_flag = false;