diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -4895,6 +4895,20 @@
 #define INIT_TTYNAME_R
 #endif
 
+#if SANITIZER_INTERCEPT_PTSNAME
+INTERCEPTOR(char *, ptsname, int fd) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, ptsname, fd);
+  char *res = REAL(ptsname)(fd);
+  if (res != nullptr)
+    COMMON_INTERCEPTOR_INITIALIZE_RANGE(res, REAL(strlen)(res) + 1);
+  return res;
+}
+#define INIT_PTSNAME COMMON_INTERCEPT_FUNCTION(ptsname);
+#else
+#define INIT_PTSNAME
+#endif
+
 #if SANITIZER_INTERCEPT_TEMPNAM
 INTERCEPTOR(char *, tempnam, char *dir, char *pfx) {
   void *ctx;
@@ -10168,6 +10182,7 @@
   INIT_TMPNAM_R;
   INIT_TTYNAME;
   INIT_TTYNAME_R;
+  INIT_PTSNAME;
   INIT_TEMPNAM;
   INIT_PTHREAD_SETNAME_NP;
   INIT_PTHREAD_GETNAME_NP;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -386,6 +386,7 @@
 #define SANITIZER_INTERCEPT_TMPNAM_R SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_TTYNAME SI_POSIX
 #define SANITIZER_INTERCEPT_TTYNAME_R SI_POSIX
+#define SANITIZER_INTERCEPT_PTSNAME SI_POSIX
 #define SANITIZER_INTERCEPT_TEMPNAM SI_POSIX
 #define SANITIZER_INTERCEPT_SINCOS SI_LINUX || SI_SOLARIS
 #define SANITIZER_INTERCEPT_REMQUO SI_POSIX
diff --git a/compiler-rt/test/msan/Linux/forkpty.cpp b/compiler-rt/test/msan/Linux/forkpty.cpp
--- a/compiler-rt/test/msan/Linux/forkpty.cpp
+++ b/compiler-rt/test/msan/Linux/forkpty.cpp
@@ -1,9 +1,10 @@
 // RUN: %clangxx_msan -O0 -g %s -lutil -o %t && %run %t
 
 #include <assert.h>
+#include <cstring>
 #include <pty.h>
+#include <stdlib.h>
 #include <unistd.h>
-#include <cstring>
 
 #include <sanitizer/msan_interface.h>
 
@@ -22,6 +23,10 @@
   char *name_p = ttyname(parent);
   assert(__msan_test_shadow(name_p, strlen(name_p) + 1) == -1);
 
+  char *ptsname_p = ptsname(parent);
+  assert(ptsname_p != nullptr);
+  assert(__msan_test_shadow(ptsname_p, strlen(ptsname_p) + 1) == -1);
+
   int parent2;
   forkpty(&parent2, NULL, NULL, NULL);
   assert(__msan_test_shadow(&parent2, sizeof(parent2)) == -1);