diff --git a/runtime/syntax/sexplib.vim b/runtime/syntax/sexplib.vim
new file mode 100644
index 0000000..55dd3fb
--- /dev/null
+++ b/runtime/syntax/sexplib.vim
@@ -0,0 +1,88 @@
+" Vim syntax file
+" Language:     S-expressions as used in Sexplib
+" Filenames:    *.sexp
+" Maintainers:  Markus Mottl      <markus.mottl@gmail.com>
+" URL:          https://github.com/ocaml/vim-ocaml
+" Last Change:  2020 Dec 31 - Updated header for Vim contribution (MM)
+"               2017 Apr 11 - Improved matching of negative numbers (MM)
+"               2012 Jun 20 - Fixed a block comment highlighting bug (MM)
+
+" For version 5.x: Clear all syntax items
+" For version 6.x: Quit when a syntax file was already loaded
+if version < 600
+  syntax clear
+elseif exists("b:current_syntax") && b:current_syntax == "sexplib"
+  finish
+endif
+
+" Sexplib is case sensitive.
+syn case match
+
+" Comments
+syn keyword  sexplibTodo contained TODO FIXME XXX NOTE
+syn region   sexplibBlockComment matchgroup=sexplibComment start="#|" matchgroup=sexplibComment end="|#" contains=ALLBUT,sexplibQuotedAtom,sexplibUnquotedAtom,sexplibEncl,sexplibComment
+syn match    sexplibSexpComment "#;" skipwhite skipempty nextgroup=sexplibQuotedAtomComment,sexplibUnquotedAtomComment,sexplibListComment,sexplibComment
+syn region   sexplibQuotedAtomComment start=+"+ skip=+\\\\\|\\"+ end=+"+ contained
+syn match    sexplibUnquotedAtomComment /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*/ contained
+syn region   sexplibListComment matchgroup=sexplibComment start="(" matchgroup=sexplibComment end=")" contained contains=ALLBUT,sexplibEncl,sexplibString,sexplibQuotedAtom,sexplibUnquotedAtom,sexplibTodo,sexplibNumber,sexplibFloat
+syn match    sexplibComment ";.*" contains=sexplibTodo
+
+" Atoms
+syn match    sexplibUnquotedAtom /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*/
+syn region   sexplibQuotedAtom    start=+"+ skip=+\\\\\|\\"+ end=+"+
+syn match    sexplibNumber        "-\=\<\d\(_\|\d\)*[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[x|X]\(\x\|_\)\+[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[o|O]\(\o\|_\)\+[l|L|n]\?\>"
+syn match    sexplibNumber        "-\=\<0[b|B]\([01]\|_\)\+[l|L|n]\?\>"
+syn match    sexplibFloat         "-\=\<\d\(_\|\d\)*\.\?\(_\|\d\)*\([eE][-+]\=\d\(_\|\d\)*\)\=\>"
+
+" Lists
+syn region   sexplibEncl transparent matchgroup=sexplibEncl start="(" matchgroup=sexplibEncl end=")" contains=ALLBUT,sexplibParenErr
+
+" Errors
+syn match    sexplibUnquotedAtomErr /\([^;()" \t#|]\|#[^;()" \t|]\||[^;()" \t#]\)[^;()" \t]*\(#|\||#\)[^;()" \t]*/
+syn match    sexplibParenErr ")"
+
+" Synchronization
+syn sync minlines=50
+syn sync maxlines=500
+
+" Define the default highlighting.
+" For version 5.7 and earlier: only when not done already
+" For version 5.8 and later: only when an item doesn't have highlighting yet
+if version >= 508 || !exists("did_sexplib_syntax_inits")
+  if version < 508
+    let did_sexplib_syntax_inits = 1
+    command -nargs=+ HiLink hi link <args>
+  else
+    command -nargs=+ HiLink hi def link <args>
+  endif
+
+  HiLink sexplibParenErr            Error
+  HiLink sexplibUnquotedAtomErr     Error
+
+  HiLink sexplibComment             Comment
+  HiLink sexplibSexpComment         Comment
+  HiLink sexplibQuotedAtomComment   Include
+  HiLink sexplibUnquotedAtomComment Comment
+  HiLink sexplibBlockComment        Comment
+  HiLink sexplibListComment         Comment
+
+  HiLink sexplibBoolean             Boolean
+  HiLink sexplibCharacter           Character
+  HiLink sexplibNumber              Number
+  HiLink sexplibFloat               Float
+  HiLink sexplibUnquotedAtom        Identifier
+  HiLink sexplibEncl                Identifier
+  HiLink sexplibQuotedAtom          Keyword
+
+  HiLink sexplibTodo                Todo
+
+  HiLink sexplibEncl                Keyword
+
+  delcommand HiLink
+endif
+
+let b:current_syntax = "sexplib"
+
+" vim: ts=8