Index: clang/utils/bash-autocomplete.sh
===================================================================
--- clang/utils/bash-autocomplete.sh
+++ clang/utils/bash-autocomplete.sh
@@ -1,15 +1,31 @@
 # Please add "source /path/to/bash-autocomplete.sh" to your .bashrc to use this.
+
+_clang_filedir()
+{
+  _filedir 2>/dev/null
+  if [[ "$?" != 0 ]]; then
+    COMPREPLY=( $( compgen -f) )
+  fi
+}
+
 _clang()
 {
-  local cur prev words cword arg flags
-  _init_completion -n : || return
+  local cur prev words cword arg flags w1 w2
+  # Require bash-completion with _init_completion
+  _init_completion -n 2>/dev/null
+  if [[ "$?" != 0 ]]; then
+    COMPREPLY=()
+    _get_comp_words_by_ref cur prev words cword
+  fi
 
   # bash always separates '=' as a token even if there's no space before/after '='.
   # On the other hand, '=' is just a regular character for clang options that
   # contain '='. For example, "-stdlib=" is defined as is, instead of "-stdlib" and "=".
   # So, we need to partially undo bash tokenization here for integrity.
-  local w1="${COMP_WORDS[$cword - 1]}"
-  local w2="${COMP_WORDS[$cword - 2]}"
+  w1="${COMP_WORDS[$cword - 1]}"
+  if [[ $cword > 1 ]]; then
+    w2="${COMP_WORDS[$cword - 2]}"
+  fi
   if [[ "$cur" == -* ]]; then
     # -foo<tab>
     arg="$cur"
@@ -28,18 +44,18 @@
   # If clang is old that it does not support --autocomplete,
   # fall back to the filename completion.
   if [[ "$?" != 0 ]]; then
-    _filedir
+    _clang_filedir
     return
   fi
 
   if [[ "$cur" == '=' ]]; then
     COMPREPLY=( $( compgen -W "$flags" -- "") )
   elif [[ "$flags" == "" || "$arg" == "" ]]; then
-    _filedir
+    _clang_filedir
   else
     # Bash automatically appends a space after '=' by default.
     # Disable it so that it works nicely for options in the form of -foo=bar.
-    [[ "${flags: -1}" == '=' ]] && compopt -o nospace
+    [[ "${flags: -1}" == '=' ]] && compopt -o nospace 2>/dev/null
     COMPREPLY=( $( compgen -W "$flags" -- "$cur" ) )
   fi
 }