diff --git a/libc/Android.bp b/libc/Android.bp
index 2fb4984..8024912 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -307,8 +307,6 @@
     defaults: ["libc_defaults"],
     srcs: [
         "upstream-netbsd/common/lib/libc/stdlib/random.c",
-        "upstream-netbsd/lib/libc/gen/ftw.c",
-        "upstream-netbsd/lib/libc/gen/nftw.c",
         "upstream-netbsd/lib/libc/gen/nice.c",
         "upstream-netbsd/lib/libc/gen/popen.c",
         "upstream-netbsd/lib/libc/gen/psignal.c",
@@ -1280,6 +1278,7 @@
         "bionic/fpclassify.cpp",
         "bionic/fsetxattr.cpp",
         "bionic/ftruncate.cpp",
+        "bionic/ftw.cpp",
         "bionic/futimens.cpp",
         "bionic/getcwd.cpp",
         "bionic/getdomainname.cpp",
diff --git a/libc/Android.mk b/libc/Android.mk
index fa392d1..02682af 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -107,6 +107,7 @@
     bionic/fpclassify.cpp \
     bionic/fsetxattr.cpp \
     bionic/ftruncate.cpp \
+    bionic/ftw.cpp \
     bionic/futimens.cpp \
     bionic/getcwd.cpp \
     bionic/getdomainname.cpp \
@@ -288,8 +289,6 @@
 
 libc_upstream_netbsd_src_files := \
     upstream-netbsd/common/lib/libc/stdlib/random.c \
-    upstream-netbsd/lib/libc/gen/ftw.c \
-    upstream-netbsd/lib/libc/gen/nftw.c \
     upstream-netbsd/lib/libc/gen/nice.c \
     upstream-netbsd/lib/libc/gen/popen.c \
     upstream-netbsd/lib/libc/gen/psignal.c \
diff --git a/libc/bionic/ftw.cpp b/libc/bionic/ftw.cpp
new file mode 100644
index 0000000..2123619
--- /dev/null
+++ b/libc/bionic/ftw.cpp
@@ -0,0 +1,124 @@
+/*
+ * Copyright (c) 2003, 2004 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Sponsored in part by the Defense Advanced Research Projects
+ * Agency (DARPA) and Air Force Research Laboratory, Air Force
+ * Materiel Command, USAF, under agreement number F39502-99-1-0512.
+ */
+
+#include <errno.h>
+#include <fts.h>
+#include <ftw.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+static int do_nftw(const char *path,
+                   int (*ftw_fn)(const char*, const struct stat*, int),
+                   int (*nftw_fn)(const char*, const struct stat*, int, FTW*),
+                   int nfds,
+                   int nftw_flags) {
+  // TODO: nfds is currently unused.
+  if (nfds < 1) {
+    errno = EINVAL;
+    return -1;
+  }
+
+  // Translate to fts_open options.
+  int fts_options = FTS_LOGICAL | FTS_COMFOLLOW | FTS_NOCHDIR;
+  if (nftw_fn) {
+    fts_options = FTS_COMFOLLOW | ((nftw_flags & FTW_PHYS) ? FTS_PHYSICAL : FTS_LOGICAL);
+    if (!(nftw_flags & FTW_CHDIR)) fts_options |= FTS_NOCHDIR;
+    if (nftw_flags & FTW_MOUNT) fts_options |= FTS_XDEV;
+  }
+  bool postorder = (nftw_flags & FTW_DEPTH) != 0;
+
+  // Call fts_open.
+  char* const paths[2] = { const_cast<char*>(path), nullptr };
+  FTS* fts = fts_open(paths, fts_options, nullptr);
+  if (fts == nullptr) {
+    return -1;
+  }
+
+  // Translate fts_read results into ftw/nftw callbacks.
+  int error = 0;
+  FTSENT* cur;
+  while (error == 0 && (cur = fts_read(fts)) != nullptr) {
+    int fn_flag;
+    switch (cur->fts_info) {
+      case FTS_D:
+        // In the postorder case, we'll translate FTS_DP to FTW_DP later.
+        // In the can't-access case, we'll translate FTS_DNR to FTW_DNR later.
+        if (postorder || access(cur->fts_path, R_OK) == -1) continue;
+        fn_flag = FTW_D;
+        break;
+      case FTS_DNR:
+        fn_flag = FTW_DNR;
+        break;
+      case FTS_DP:
+        if (!postorder) continue;
+        fn_flag = FTW_DP;
+        break;
+      case FTS_F:
+      case FTS_DEFAULT:
+        fn_flag = FTW_F;
+        break;
+      case FTS_NS:
+      case FTS_NSOK:
+        fn_flag = FTW_NS;
+        break;
+      case FTS_SL:
+        fn_flag = FTW_SL;
+        break;
+      case FTS_SLNONE:
+        fn_flag = (nftw_fn != nullptr) ? FTW_SLN : FTW_NS;
+        break;
+      case FTS_DC:
+        errno = ELOOP;
+        error = -1;
+        continue;
+      default:
+        error = -1;
+        continue;
+    }
+
+    // Call the appropriate function.
+    if (nftw_fn != nullptr) {
+      FTW ftw;
+      ftw.base = cur->fts_pathlen - cur->fts_namelen;
+      ftw.level = cur->fts_level;
+      error = nftw_fn(cur->fts_path, cur->fts_statp, fn_flag, &ftw);
+    } else {
+      error = ftw_fn(cur->fts_path, cur->fts_statp, fn_flag);
+    }
+  }
+
+  int saved_errno = errno;
+  if (fts_close(fts) != 0 && error == 0) {
+    error = -1;
+  } else {
+    errno = saved_errno;
+  }
+  return error;
+}
+
+int ftw(const char* path, int (*ftw_fn)(const char*, const struct stat*, int), int nfds) {
+  return do_nftw(path, ftw_fn, nullptr, nfds, 0);
+}
+
+int nftw(const char* path, int (*nftw_fn)(const char*, const struct stat*, int, FTW*),
+         int nfds, int nftw_flags) {
+  return do_nftw(path, nullptr, nftw_fn, nfds, nftw_flags);
+}
diff --git a/libc/upstream-netbsd/lib/libc/gen/ftw.c b/libc/upstream-netbsd/lib/libc/gen/ftw.c
deleted file mode 100644
index a7f6bbd..0000000
--- a/libc/upstream-netbsd/lib/libc/gen/ftw.c
+++ /dev/null
@@ -1,98 +0,0 @@
-/* $NetBSD: ftw.c,v 1.1 2005/12/30 23:07:32 agc Exp $ */
-
-/*	From OpenBSD: ftw.c,v 1.2 2003/07/21 21:15:32 millert Exp 	*/
-
-/*
- * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- * Sponsored in part by the Defense Advanced Research Projects
- * Agency (DARPA) and Air Force Research Laboratory, Air Force
- * Materiel Command, USAF, under agreement number F39502-99-1-0512.
- */
-#include <sys/cdefs.h>
-
-#ifndef lint
-__RCSID("$NetBSD: ftw.c,v 1.1 2005/12/30 23:07:32 agc Exp $");
-#endif
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <fts.h>
-#include <ftw.h>
-#include <limits.h>
-
-int
-ftw(const char *path, int (*fn)(const char *, const struct stat *, int),
-    int nfds)
-{
-	/* LINTED */
-	char * const paths[2] = { __UNCONST(path), NULL };
-	FTSENT *cur;
-	FTS *ftsp;
-	int fnflag, error, sverrno;
-
-	/* XXX - nfds is currently unused */
-	if (nfds < 1 || nfds > OPEN_MAX) {
-		errno = EINVAL;
-		return (-1);
-	}
-
-	ftsp = fts_open(paths, FTS_COMFOLLOW | FTS_NOCHDIR, NULL);
-	if (ftsp == NULL)
-		return (-1);
-	error = 0;
-	while ((cur = fts_read(ftsp)) != NULL) {
-		switch (cur->fts_info) {
-		case FTS_D:
-			fnflag = FTW_D;
-			break;
-		case FTS_DNR:
-			fnflag = FTW_DNR;
-			break;
-		case FTS_DP:
-			/* we only visit in preorder */
-			continue;
-		case FTS_F:
-		case FTS_DEFAULT:
-			fnflag = FTW_F;
-			break;
-		case FTS_NS:
-		case FTS_NSOK:
-		case FTS_SLNONE:
-			fnflag = FTW_NS;
-			break;
-		case FTS_SL:
-			fnflag = FTW_SL;
-			break;
-		case FTS_DC:
-			errno = ELOOP;
-			/* FALLTHROUGH */
-		default:
-			error = -1;
-			goto done;
-		}
-		error = fn(cur->fts_path, cur->fts_statp, fnflag);
-		if (error != 0)
-			break;
-	}
-done:
-	sverrno = errno;
-	if (fts_close(ftsp) != 0 && error == 0)
-		error = -1;
-	else
-		errno = sverrno;
-	return (error);
-}
diff --git a/libc/upstream-netbsd/lib/libc/gen/nftw.c b/libc/upstream-netbsd/lib/libc/gen/nftw.c
deleted file mode 100644
index 0e51342..0000000
--- a/libc/upstream-netbsd/lib/libc/gen/nftw.c
+++ /dev/null
@@ -1,114 +0,0 @@
-/* $NetBSD */
-
-/*	From OpenBSD: nftw.c,v 1.2 2003/07/21 21:15:32 millert Exp 	*/
-
-/*
- * Copyright (c) 2003 Todd C. Miller <Todd.Miller@courtesan.com>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- * Sponsored in part by the Defense Advanced Research Projects
- * Agency (DARPA) and Air Force Research Laboratory, Air Force
- * Materiel Command, USAF, under agreement number F39502-99-1-0512.
- */
-
-#include <sys/cdefs.h>
-
-#ifndef lint
-__RCSID("$NetBSD: nftw.c,v 1.1 2005/12/30 23:07:32 agc Exp $");
-#endif
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <fts.h>
-#include <ftw.h>
-#include <limits.h>
-
-int
-nftw(const char *path, int (*fn)(const char *, const struct stat *, int,
-     struct FTW *), int nfds, int ftwflags)
-{
-	/* LINTED */
-	char * const paths[2] = { __UNCONST(path), NULL };
-	struct FTW f;
-	FTSENT *cur;
-	FTS *ftsp;
-	int ftsflags, fnflag, error, postorder, sverrno;
-
-	/* XXX - nfds is currently unused */
-	if (nfds < 1 || nfds > OPEN_MAX) {
-		errno = EINVAL;
-		return (-1);
-	}
-
-	ftsflags = FTS_COMFOLLOW;
-	if (!(ftwflags & FTW_CHDIR))
-		ftsflags |= FTS_NOCHDIR;
-	if (ftwflags & FTW_MOUNT)
-		ftsflags |= FTS_XDEV;
-	if (ftwflags & FTW_PHYS)
-		ftsflags |= FTS_PHYSICAL;
-	postorder = (ftwflags & FTW_DEPTH) != 0;
-	ftsp = fts_open(paths, ftsflags, NULL);
-	if (ftsp == NULL)
-		return (-1);
-	error = 0;
-	while ((cur = fts_read(ftsp)) != NULL) {
-		switch (cur->fts_info) {
-		case FTS_D:
-			if (postorder)
-				continue;
-			fnflag = FTW_D;
-			break;
-		case FTS_DNR:
-			fnflag = FTW_DNR;
-			break;
-		case FTS_DP:
-			if (!postorder)
-				continue;
-			fnflag = FTW_DP;
-			break;
-		case FTS_F:
-		case FTS_DEFAULT:
-			fnflag = FTW_F;
-			break;
-		case FTS_NS:
-		case FTS_NSOK:
-			fnflag = FTW_NS;
-			break;
-		case FTS_SL:
-			fnflag = FTW_SL;
-			break;
-		case FTS_SLNONE:
-			fnflag = FTW_SLN;
-			break;
-		case FTS_DC:
-			errno = ELOOP;
-			/* FALLTHROUGH */
-		default:
-			error = -1;
-			goto done;
-		}
-		f.base = cur->fts_pathlen - cur->fts_namelen;
-		f.level = cur->fts_level;
-		error = fn(cur->fts_path, cur->fts_statp, fnflag, &f);
-		if (error != 0)
-			break;
-	}
-done:
-	sverrno = errno;
-	(void) fts_close(ftsp);
-	errno = sverrno;
-	return (error);
-}