diff --git a/libc/bionic/exec.cpp b/libc/bionic/exec.cpp
new file mode 100644
index 0000000..c1e73a5
--- /dev/null
+++ b/libc/bionic/exec.cpp
@@ -0,0 +1,163 @@
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/types.h>
+#include <sys/uio.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <paths.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+extern "C" char** environ;
+
+enum ExecVariant { kIsExecL, kIsExecLE, kIsExecLP };
+
+static int __execl(const char* name, const char* argv0, ExecVariant variant, va_list ap) {
+  // Count the arguments.
+  va_list count_ap;
+  va_copy(count_ap, ap);
+  size_t n = 1;
+  while (va_arg(count_ap, char*) != nullptr) {
+    ++n;
+  }
+  va_end(count_ap);
+
+  // Construct the new argv.
+  char* argv[n + 1];
+  argv[0] = const_cast<char*>(argv0);
+  n = 1;
+  while ((argv[n] = va_arg(ap, char*)) != nullptr) {
+    ++n;
+  }
+
+  // Collect the argp too.
+  char** argp = (variant == kIsExecLE) ? va_arg(ap, char**) : environ;
+
+  va_end(ap);
+
+  return (variant == kIsExecLP) ? execvp(name, argv) : execve(name, argv, argp);
+}
+
+int execl(const char* name, const char* arg, ...) {
+  va_list ap;
+  va_start(ap, arg);
+  return __execl(name, arg, kIsExecL, ap);
+}
+
+int execle(const char* name, const char* arg, ...) {
+  va_list ap;
+  va_start(ap, arg);
+  return __execl(name, arg, kIsExecLE, ap);
+}
+
+int execlp(const char* name, const char* arg, ...) {
+  va_list ap;
+  va_start(ap, arg);
+  return __execl(name, arg, kIsExecLP, ap);
+}
+
+int execv(const char* name, char* const* argv) {
+  return execve(name, argv, environ);
+}
+
+int execvp(const char* name, char* const* argv) {
+  return execvpe(name, argv, environ);
+}
+
+static int __exec_as_script(char* buf, char* const* argv, char* const* envp) {
+  size_t arg_count = 0;
+  while (argv[arg_count] != nullptr) ++arg_count;
+
+  char* script_argv[arg_count + 2];
+  script_argv[0] = const_cast<char*>("sh");
+  script_argv[1] = buf;
+  bcopy(argv + 1, script_argv + 2, arg_count * sizeof(char*));
+  return execve(_PATH_BSHELL, script_argv, envp);
+}
+
+int execvpe(const char* name, char* const* argv, char* const* envp) {
+  // Do not allow null name.
+  if (name == nullptr || *name == '\0') {
+    errno = ENOENT;
+    return -1;
+  }
+
+  // If it's an absolute or relative path name, it's easy.
+  if (strchr(name, '/')) return execve(name, argv, envp);
+
+  // Get the path we're searching.
+  const char* path = getenv("PATH");
+  if (path == nullptr) path = _PATH_DEFPATH;
+
+  // Make a writable copy.
+  size_t len = strlen(path) + 1;
+  char writable_path[len];
+  memcpy(writable_path, path, len);
+
+  bool saw_EACCES = false;
+
+  // Try each element of $PATH in turn...
+  char* strsep_buf = writable_path;
+  const char* dir;
+  while ((dir = strsep(&strsep_buf, ":"))) {
+    // It's a shell path: double, leading and trailing colons
+    // mean the current directory.
+    if (*dir == '\0') dir = const_cast<char*>(".");
+
+    size_t dir_len = strlen(dir);
+    size_t name_len = strlen(name);
+
+    char buf[dir_len + 1 + name_len + 1];
+    mempcpy(mempcpy(mempcpy(buf, dir, dir_len), "/", 1), name, name_len + 1);
+
+    execve(buf, argv, envp);
+    switch (errno) {
+    case EISDIR:
+    case ELOOP:
+    case ENAMETOOLONG:
+    case ENOENT:
+    case ENOTDIR:
+      break;
+    case ENOEXEC:
+      return __exec_as_script(buf, argv, envp);
+    case EACCES:
+      saw_EACCES = true;
+      break;
+    default:
+      return -1;
+    }
+  }
+  if (saw_EACCES) errno = EACCES;
+  return -1;
+}