diff --git a/lldb/source/Host/common/File.cpp b/lldb/source/Host/common/File.cpp
--- a/lldb/source/Host/common/File.cpp
+++ b/lldb/source/Host/common/File.cpp
@@ -103,7 +103,22 @@
 FILE *File::GetStream() {
   if (!StreamIsValid()) {
     if (DescriptorIsValid()) {
-      const char *mode = GetStreamOpenModeFromOptions(m_options);
+      const char *mode = nullptr;
+      if (m_options) {
+        mode = GetStreamOpenModeFromOptions(m_options);
+      } else {
+       int fdflags = ::fcntl(m_descriptor, F_GETFL);
+       if (fdflags >= 0) {
+          if (fdflags & O_RDWR) {
+            mode = "r+";
+          } else if (fdflags & O_WRONLY) {
+            mode = "w";
+          } else {
+            mode = "r";
+          }
+        }
+      }
+
       if (mode) {
         if (!m_should_close_fd) {
 // We must duplicate the file descriptor if we don't own it because when you