diff --git a/cranelift/docs/conf.py b/cranelift/docs/conf.py
index 58cc740464..120d32011a 100644
--- a/cranelift/docs/conf.py
+++ b/cranelift/docs/conf.py
@@ -34,7 +34,8 @@ extensions = [
     'sphinx.ext.todo',
     'sphinx.ext.mathjax',
     'sphinx.ext.ifconfig',
-    'cton_domain'
+    'cton_domain',
+    'cton_lexer',
 ]
 
 # Add any paths that contain templates here, relative to this directory.
diff --git a/cranelift/docs/cton_lexer.py b/cranelift/docs/cton_lexer.py
new file mode 100644
index 0000000000..02e8945580
--- /dev/null
+++ b/cranelift/docs/cton_lexer.py
@@ -0,0 +1,36 @@
+# -*- coding: utf-8 -*-
+#
+# Pygments lexer for Cretonne.
+
+from pygments.lexer import RegexLexer, bygroups
+from pygments.token import *
+
+class CretonneLexer(RegexLexer):
+    name = 'Cretonne'
+    aliases = ['cton']
+    filenames = ['*.cton']
+
+    tokens = {
+        'root': [
+            (r';.*?$', Comment.Single),
+            (r'\b(function|entry)\b', Keyword),
+            (r'\b(align)\b', Name.Attribute),
+            (r'\b(v\d+)?(bool|i\d+|f32|f64)\b', Keyword.Type),
+            (r'\d+', Number.Integer),
+            (r'0[xX][0-9a-fA-F]+', Number.Hex),
+            (r'(v|ss|ebb)\d+', Name.Variable),
+            (r'(ebb)\d+', Name.Label),
+            (r'(=)( *)([a-z]\w*)', bygroups(Operator, Whitespace, Name.Function)),
+            (r'^( +)([a-z]\w*\b)(?! *[,=])', bygroups(Whitespace, Name.Function)),
+            (r'[a-z]\w*', Name),
+            (r'->|=|:', Operator),
+            (r'[{}(),.]', Punctuation),
+            (r'[ \t]+', Text),
+        ]
+    }
+
+def setup(app):
+    """Setup Sphinx extension."""
+    app.add_lexer('cton', CretonneLexer())
+
+    return { 'version' : '0.1' }