Index: compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -6104,6 +6104,40 @@
 #define INIT_FOPEN
 #endif
 
+#if SANITIZER_INTERCEPT_FLOPEN
+INTERCEPTOR(int, flopen, const char *path, int flags, ...) {
+  void *ctx;
+  va_list ap;
+  va_start(ap, flags);
+  u16 mode = static_cast<u16>(va_arg(ap, u32));
+  va_end(ap);
+  COMMON_INTERCEPTOR_ENTER(ctx, flopen, path, flags, mode);
+  if (path) {
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, path, REAL(strlen)(path) + 1);
+  }
+  return REAL(flopen)(path, flags, mode);
+}
+
+INTERCEPTOR(int, flopenat, int dirfd, const char *path, int flags, ...) {
+  void *ctx;
+  va_list ap;
+  va_start(ap, flags);
+  u16 mode = static_cast<u16>(va_arg(ap, u32));
+  va_end(ap);
+  COMMON_INTERCEPTOR_ENTER(ctx, flopen, path, flags, mode);
+  if (path) {
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, path, REAL(strlen)(path) + 1);
+  }
+  return REAL(flopenat)(dirfd, path, flags, mode);
+}
+
+#define INIT_FLOPEN    \
+  COMMON_INTERCEPT_FUNCTION(flopen); \
+  COMMON_INTERCEPT_FUNCTION(flopenat);
+#else
+#define INIT_FLOPEN
+#endif
+
 #if SANITIZER_INTERCEPT_FOPEN64
 INTERCEPTOR(__sanitizer_FILE *, fopen64, const char *path, const char *mode) {
   void *ctx;
@@ -10269,6 +10303,7 @@
   INIT_LIBIO_INTERNALS;
   INIT_FOPEN;
   INIT_FOPEN64;
+  INIT_FLOPEN;
   INIT_OPEN_MEMSTREAM;
   INIT_OBSTACK;
   INIT_FFLUSH;
Index: compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -577,6 +577,7 @@
   (SI_POSIX && !(SANITIZER_MAC && SANITIZER_I386))
 #define SANITIZER_INTERCEPT_UNAME (SI_POSIX && !SI_FREEBSD)
 #define SANITIZER_INTERCEPT___XUNAME SI_FREEBSD
+#define SANITIZER_INTERCEPT_FLOPEN SI_FREEBSD
 
 // This macro gives a way for downstream users to override the above
 // interceptor macros irrespective of the platform they are on. They have
Index: compiler-rt/test/sanitizer_common/TestCases/FreeBSD/flopen.cc
===================================================================
--- /dev/null
+++ compiler-rt/test/sanitizer_common/TestCases/FreeBSD/flopen.cc
@@ -0,0 +1,20 @@
+// RUN: %clangxx -O0 -g %s -o %t -lutil && %run %t 2>&1 | FileCheck %s
+
+#include <sys/fcntl.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <libutil.h>
+
+int main(void) {
+  char buf[256];
+  arc4random_buf(buf, sizeof(buf));
+  int fd = flopen(nullptr, 0, 0);
+  assert(fd == -1);
+  fd = flopen("/TMP", O_RDONLY, 0600);
+  assert(fd == -1);
+  int dirfd = open("/tmp", O_CLOEXEC | O_DIRECTORY);
+  assert(dirfd != -1);
+  fd = flopenat(dirfd, buf, O_RDONLY, 0666);
+  assert(fd == -1);
+  return 0;
+}