diff --git a/runtime/autoload/dist/ft.vim b/runtime/autoload/dist/ft.vim
index c8942eb..214cf6e 100644
--- a/runtime/autoload/dist/ft.vim
+++ b/runtime/autoload/dist/ft.vim
@@ -169,6 +169,14 @@
   endif
 enddef
 
+export def FTll()
+  if getline(1) =~ ';\|\<source_filename\>\|\<target\>'
+    setf llvm
+  else
+    setf lifelines
+  endif
+enddef
+
 export def FTlpc()
   if exists("g:lpc_syntax_for_c")
     var lnum = 1
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 897f356..085e4bd 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1351,7 +1351,7 @@
 au BufNewFile,BufRead lftp.conf,.lftprc,*lftp/rc	setf lftp
 
 " Lifelines (or Lex for C++!)
-au BufNewFile,BufRead *.ll			setf lifelines
+au BufNewFile,BufRead *.ll			call dist#ft#FTll()
 
 " Lilo: Linux loader
 au BufNewFile,BufRead lilo.conf			setf lilo
diff --git a/runtime/ftplugin/llvm.vim b/runtime/ftplugin/llvm.vim
new file mode 100644
index 0000000..148b12f
--- /dev/null
+++ b/runtime/ftplugin/llvm.vim
@@ -0,0 +1,12 @@
+" Vim filetype plugin file
+" Language:	LLVM IR
+" Last Change:	2024 Oct 22
+" Maintainer:	Wu, Zhenyu <wuzhenyu@ustc.edu>
+
+if exists("b:did_ftplugin") | finish | endif
+let b:did_ftplugin = 1
+
+setl comments=:;
+setl commentstring=;\ %s
+
+let b:undo_ftplugin = "setl commentstring< comments<"
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index 8a89905..215d750 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -2446,6 +2446,24 @@
   filetype off
 endfunc
 
+func Test_ll_file()
+  filetype on
+
+  " LLVM IR
+  call writefile(['target triple = "nvptx64-nvidia-cuda"'], 'Xfile.ll', 'D')
+  split Xfile.ll
+  call assert_equal('llvm', &filetype)
+  bwipe!
+
+  " lifelines
+  call writefile(['proc main() {}'], 'Xfile.ll', 'D')
+  split Xfile.ll
+  call assert_equal('lifelines', &filetype)
+  bwipe!
+
+  filetype off
+endfunc
+
 func Test_lsl_file()
   filetype on
 
diff --git a/src/version.c b/src/version.c
index 79b3099..7ba9d87 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    866,
+/**/
     865,
 /**/
     864,