Index: lib/msan/msan_interceptors.cc
===================================================================
--- lib/msan/msan_interceptors.cc
+++ lib/msan/msan_interceptors.cc
@@ -35,6 +35,7 @@
 #include "sanitizer_common/sanitizer_tls_get_addr.h"
 
 #if SANITIZER_NETBSD
+#define fstat __fstat50
 #define gettimeofday __gettimeofday50
 #define getrusage __getrusage50
 #endif
@@ -688,6 +689,19 @@
   return res;
 }
 
+#if SANITIZER_NETBSD
+INTERCEPTOR(int, fstat, int fd, void *buf) {
+  ENSURE_MSAN_INITED();
+  int res = REAL(fstat)(fd, buf);
+  if (!res)
+    __msan_unpoison(buf, __sanitizer::struct_stat_sz);
+  return res;
+}
+#define MSAN_MAYBE_INTERCEPT_FSTAT INTERCEPT_FUNCTION(fstat)
+#else
+#define MSAN_MAYBE_INTERCEPT_FSTAT
+#endif
+
 #if !SANITIZER_FREEBSD && !SANITIZER_NETBSD
 INTERCEPTOR(int, __fxstat, int magic, int fd, void *buf) {
   ENSURE_MSAN_INITED();
@@ -1633,6 +1647,7 @@
   INTERCEPT_FUNCTION(putenv);
   INTERCEPT_FUNCTION(gettimeofday);
   MSAN_MAYBE_INTERCEPT_FCVT;
+  MSAN_MAYBE_INTERCEPT_FSTAT;
   MSAN_MAYBE_INTERCEPT___FXSTAT;
   MSAN_INTERCEPT_FSTATAT;
   MSAN_MAYBE_INTERCEPT___FXSTAT64;
Index: test/msan/fstat.cc
===================================================================
--- test/msan/fstat.cc
+++ test/msan/fstat.cc
@@ -0,0 +1,15 @@
+// RUN: %clangxx_msan -O0 %s -o %t && %run %t
+
+#include <sys/stat.h>
+#include <stdlib.h>
+
+int main(void) {
+  struct stat st;
+  if (fstat(0, &st))
+    exit(1);
+
+  if (S_ISBLK(st.st_mode))
+    exit(0);
+
+  return 0;
+}