diff --git a/lldb/source/Host/common/PseudoTerminal.cpp b/lldb/source/Host/common/PseudoTerminal.cpp
--- a/lldb/source/Host/common/PseudoTerminal.cpp
+++ b/lldb/source/Host/common/PseudoTerminal.cpp
@@ -22,6 +22,10 @@
 
 #include "lldb/Host/PosixApi.h"
 
+#if defined(__APPLE__)
+#include <Availability.h>
+#endif
+
 #if defined(__ANDROID__)
 int posix_openpt(int flags);
 #endif
@@ -99,21 +103,33 @@
       std::error_code(errno, std::generic_category()));
 }
 
-std::string PseudoTerminal::GetSecondaryName() const {
-  assert(m_primary_fd >= 0);
-#if HAVE_PTSNAME_R
-  char buf[PATH_MAX];
-  buf[0] = '\0';
-  int r = ptsname_r(m_primary_fd, buf, sizeof(buf));
-  (void)r;
-  assert(r == 0);
-  return buf;
-#else
+static std::string use_ptsname(int fd) {
   static std::mutex mutex;
   std::lock_guard<std::mutex> guard(mutex);
-  const char *r = ptsname(m_primary_fd);
+  const char *r = ptsname(fd);
   assert(r != nullptr);
   return r;
+}
+
+std::string PseudoTerminal::GetSecondaryName() const {
+  assert(m_primary_fd >= 0);
+#if HAVE_PTSNAME_R
+#if defined(__APPLE__)
+  if (__builtin_available(macos 10.13.4, iOS 11.3, tvOS 11.3, watchOS 4.4, *)) {
+#endif
+    char buf[PATH_MAX];
+    buf[0] = '\0';
+    int r = ptsname_r(m_primary_fd, buf, sizeof(buf));
+    (void)r;
+    assert(r == 0);
+    return buf;
+#if defined(__APPLE__)
+  } else {
+    return use_ptsname(m_primary_fd);
+  }
+#endif
+#else
+  return use_ptsname(m_primary_fd);
 #endif
 }