diff --git a/libc/Android.bp b/libc/Android.bp
index 46312d8..df8871a 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1113,6 +1113,7 @@
         "bionic/open.cpp",
         "bionic/pathconf.cpp",
         "bionic/pause.cpp",
+        "bionic/pidfd.cpp",
         "bionic/pipe.cpp",
         "bionic/poll.cpp",
         "bionic/posix_fadvise.cpp",
diff --git a/libc/SECCOMP_ALLOWLIST_COMMON.TXT b/libc/SECCOMP_ALLOWLIST_COMMON.TXT
index 804676e..20c1441 100644
--- a/libc/SECCOMP_ALLOWLIST_COMMON.TXT
+++ b/libc/SECCOMP_ALLOWLIST_COMMON.TXT
@@ -72,5 +72,3 @@
 int rt_sigtimedwait_time64(const sigset64_t*, siginfo_t*, const timespec64*, size_t) lp32
 int futex_time64(int*, int, int, const timespec64*, int*, int) lp32
 int sched_rr_get_interval_time64(pid_t, timespec64*) lp32
-# Since Linux 5.3, not in glibc.
-int pidfd_open(pid_t pid, unsigned int flags) all
diff --git a/libc/SYSCALLS.TXT b/libc/SYSCALLS.TXT
index 33a8a61..d263508 100644
--- a/libc/SYSCALLS.TXT
+++ b/libc/SYSCALLS.TXT
@@ -358,3 +358,8 @@
 
 # <sys/random.h>
 ssize_t getrandom(void*, size_t, unsigned) all
+
+# <sys/pidfd.h>
+int __pidfd_open:pidfd_open(pid_t, unsigned int) all
+int __pidfd_getfd:pidfd_getfd(int, int, unsigned int) all
+int pidfd_send_signal(int, int, siginfo_t*, unsigned int) all
diff --git a/libc/bionic/pidfd.cpp b/libc/bionic/pidfd.cpp
new file mode 100644
index 0000000..1dcb1fd
--- /dev/null
+++ b/libc/bionic/pidfd.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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/pidfd.h>
+
+#include "private/bionic_fdtrack.h"
+
+extern "C" int __pidfd_open(pid_t pid, unsigned int flags);
+extern "C" int __pidfd_getfd(int pidfd, int targetfd, unsigned int flags);
+
+int pidfd_open(pid_t pid, unsigned int flags) {
+  return FDTRACK_CREATE(__pidfd_open(pid, flags));
+}
+
+int pidfd_getfd(int pidfd, int targetfd, unsigned int flags) {
+  return FDTRACK_CREATE(__pidfd_getfd(pidfd, targetfd, flags));
+}
diff --git a/libc/include/sys/pidfd.h b/libc/include/sys/pidfd.h
new file mode 100644
index 0000000..6d0e809
--- /dev/null
+++ b/libc/include/sys/pidfd.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+#pragma once
+
+/**
+ * @file sys/pidfd.h
+ * @brief File descriptors representing processes.
+ */
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#include <bits/signal_types.h>
+
+__BEGIN_DECLS
+
+/**
+ * [pidfd_open(2)](https://man7.org/linux/man-pages/man2/pidfd_open.2.html)
+ * opens a file descriptor that refers to a process. This file descriptor will
+ * have the close-on-exec flag set by default.
+ *
+ * Returns a new file descriptor on success and returns -1 and sets `errno` on
+ * failure.
+ *
+ * Available since API level 31.
+ */
+int pidfd_open(pid_t __pid, unsigned int __flags) __INTRODUCED_IN(31);
+
+/**
+ * [pidfd_getfd(2)](https://man7.org/linux/man-pages/man2/pidfd_open.2.html)
+ * dups a file descriptor from another process. This file descriptor will have
+ * the close-on-exec flag set by default.
+ *
+ * Returns a new file descriptor on success and returns -1 and sets `errno` on
+ * failure.
+ *
+ * Available since API level 31.
+ */
+int pidfd_getfd(int __pidfd, int __targetfd, unsigned int __flags) __INTRODUCED_IN(31);
+
+/**
+ * [pidfd_send_signal(2)](https://man7.org/linux/man-pages/man2/pidfd_send_signal.2.html)
+ * sends a signal to another process.
+ *
+ * Returns 0 on success and returns -1 and sets `errno` on failure.
+ *
+ * Available since API level 31.
+ */
+int pidfd_send_signal(int __pidfd, int __sig, siginfo_t *__info, unsigned int __flags) __INTRODUCED_IN(31);
+
+__END_DECLS
diff --git a/libc/libc.map.txt b/libc/libc.map.txt
index f4f35ac..51a1076 100644
--- a/libc/libc.map.txt
+++ b/libc/libc.map.txt
@@ -1558,6 +1558,9 @@
     __libc_register_dynamic_tls_listeners;
     ffsl;
     ffsll;
+    pidfd_getfd;
+    pidfd_open;
+    pidfd_send_signal;
     process_madvise;
 } LIBC_R;
 
diff --git a/tests/Android.bp b/tests/Android.bp
index 9b7e6f5..02a33ee 100644
--- a/tests/Android.bp
+++ b/tests/Android.bp
@@ -375,6 +375,7 @@
         "netinet_ip_icmp_test.cpp",
         "netinet_udp_test.cpp",
         "nl_types_test.cpp",
+        "pidfd_test.cpp",
         "poll_test.cpp",
         "prio_ctor_test.cpp",
         "pthread_test.cpp",
diff --git a/tests/NOTICE b/tests/NOTICE
index 305e816..a58cf46 100644
--- a/tests/NOTICE
+++ b/tests/NOTICE
@@ -338,3 +338,19 @@
 
 -------------------------------------------------------------------
 
+Copyright (C) 2021 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.
+
+-------------------------------------------------------------------
+
diff --git a/tests/fdtrack_test.cpp b/tests/fdtrack_test.cpp
index 95758bf..13f1b2e 100644
--- a/tests/fdtrack_test.cpp
+++ b/tests/fdtrack_test.cpp
@@ -28,6 +28,8 @@
 #include <unistd.h>
 
 #if defined(__BIONIC__)
+#include <sys/pidfd.h>
+
 #include "platform/bionic/fdtrack.h"
 #include "platform/bionic/reserved_signals.h"
 #endif
@@ -61,9 +63,7 @@
   events.clear();
 
   android_fdtrack_hook_t previous = nullptr;
-  android_fdtrack_hook_t hook = [](android_fdtrack_event* event) {
-    events.push_back(*event);
-  };
+  android_fdtrack_hook_t hook = [](android_fdtrack_event* event) { events.push_back(*event); };
 
   if (!android_fdtrack_compare_exchange_hook(&previous, hook)) {
     errx(1, "failed to exchange hook: previous hook was %p", previous);
@@ -178,7 +178,7 @@
     static std::vector<int> expected_fds;                                                        \
     auto events = FdtrackRun([]() { SetFdResult(&expected_fds, expression); });                  \
     for (auto& fd : expected_fds) {                                                              \
-      ASSERT_NE(-1, fd);                                                                         \
+      ASSERT_NE(-1, fd) << strerror(errno);                                                      \
     }                                                                                            \
     if (events.size() != expected_fds.size()) {                                                  \
       fprintf(stderr, "too many events received: expected %zu, got %zu:\n", expected_fds.size(), \
@@ -211,6 +211,37 @@
 FDTRACK_TEST(openat, openat(AT_EMPTY_PATH, "/dev/null", O_WRONLY | O_CLOEXEC));
 FDTRACK_TEST(socket, socket(AF_UNIX, SOCK_STREAM, 0));
 
+FDTRACK_TEST(pidfd_open, ({
+  int rc = pidfd_open(getpid(), 0);
+  if (rc == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_open not available";
+  }
+  rc;
+}));
+
+FDTRACK_TEST(pidfd_getfd, ({
+  android_fdtrack_set_enabled(false);
+  int pidfd_self = pidfd_open(getpid(), 0);
+  if (pidfd_self == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_open not available";
+  }
+  android_fdtrack_set_enabled(true);
+
+  int rc = pidfd_getfd(pidfd_self, STDIN_FILENO, 0);
+  if (rc == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_getfd not available";
+  }
+
+  android_fdtrack_set_enabled(false);
+  close(pidfd_self);
+  android_fdtrack_set_enabled(true);
+
+  rc;
+}));
+
 FDTRACK_TEST(dup, dup(STDOUT_FILENO));
 FDTRACK_TEST(dup2, dup2(STDOUT_FILENO, STDERR_FILENO));
 FDTRACK_TEST(dup3, dup3(STDOUT_FILENO, STDERR_FILENO, 0));
diff --git a/tests/pidfd_test.cpp b/tests/pidfd_test.cpp
new file mode 100644
index 0000000..7c691ef
--- /dev/null
+++ b/tests/pidfd_test.cpp
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2021 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 <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#if defined(__BIONIC__)
+#include <sys/pidfd.h>
+#endif
+
+#include <android-base/unique_fd.h>
+
+#include <gtest/gtest.h>
+
+#include "BionicDeathTest.h"
+
+using android::base::unique_fd;
+using namespace std::chrono_literals;
+
+using pidfd_DeathTest = BionicDeathTest;
+
+TEST(pidfd, pidfd_open) {
+#if defined(__BIONIC__)
+  pid_t child = fork();
+  ASSERT_NE(-1, child);
+  if (child == 0) {
+    _exit(42);
+  }
+
+  unique_fd pidfd(pidfd_open(child, 0));
+  if (pidfd.get() == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_open not available";
+  }
+
+  siginfo_t siginfo;
+  int rc = waitid(P_PIDFD, pidfd.get(), &siginfo, WEXITED);
+  if (rc == -1) {
+    ASSERT_EQ(EINVAL, errno) << strerror(errno);
+    GTEST_SKIP() << "P_PIDFD not available";
+  }
+
+  ASSERT_EQ(child, siginfo.si_pid);
+#endif
+}
+
+TEST(pidfd, pidfd_getfd) {
+#if defined(__BIONIC__)
+  unique_fd r, w;
+  ASSERT_TRUE(android::base::Pipe(&r, &w));
+  unique_fd self(pidfd_open(getpid(), 0));
+  if (self.get() == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_open not available";
+  }
+
+  unique_fd dup(pidfd_getfd(self.get(), r.get(), 0));
+  if (dup.get() == -1) {
+    ASSERT_EQ(ENOSYS, errno) << strerror(errno);
+    GTEST_SKIP() << "pidfd_getfd not available";
+  }
+
+  ASSERT_NE(r.get(), dup.get());
+  ASSERT_EQ(3, write(w.get(), "foo", 3));
+  char buf[4];
+  ASSERT_EQ(3, read(dup.get(), buf, sizeof(buf)));
+  ASSERT_EQ(0, memcmp(buf, "foo", 3));
+#endif
+}
+
+TEST_F(pidfd_DeathTest, pidfd_send_signal) {
+#if defined(__BIONIC__)
+  unique_fd self(pidfd_open(getpid(), 0));
+  if (self.get() == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_open not available";
+  }
+
+  if (pidfd_send_signal(self.get(), 0, nullptr, 0) == -1) {
+    ASSERT_EQ(ENOSYS, errno);
+    GTEST_SKIP() << "pidfd_send_signal not available";
+  }
+
+  ASSERT_EXIT(({
+                // gtest will fork a child off for ASSERT_EXIT: `self` refers to the parent.
+                unique_fd child(pidfd_open(getpid(), 0));
+                pidfd_send_signal(child.get(), SIGINT, nullptr, 0);
+              }),
+              testing::KilledBySignal(SIGINT), "");
+
+#endif
+}