diff --git a/cl/doc.go b/cl/doc.go
index 3e331c065..1b162d6fe 100644
--- a/cl/doc.go
+++ b/cl/doc.go
@@ -59,11 +59,12 @@ func toLineComments(raw string) []*ast.Comment {
 	switch {
 	case strings.HasPrefix(raw, "/*"):
 		body := strings.TrimPrefix(raw, "/*")
+		body = strings.TrimPrefix(body, "!")
 		body = strings.TrimSuffix(body, "*/")
 		for _, line := range strings.Split(body, "\n") {
 			line = strings.TrimSpace(line)
 			// Drop a Doxygen/Javadoc-style leading "*" decoration.
-			if line == "*" {
+			if strings.Trim(line, "*") == "" {
 				line = ""
 			} else if s, ok := strings.CutPrefix(line, "* "); ok {
 				line = s
diff --git a/cl/doc_test.go b/cl/doc_test.go
new file mode 100644
index 000000000..ab1d92e09
--- /dev/null
+++ b/cl/doc_test.go
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2026 The XGo Authors (xgo.dev). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package cl
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestToLineComments(t *testing.T) {
+	tests := []struct {
+		name string
+		raw  string
+		want []string
+	}{
+		{
+			name: "asterisk banner delimiters",
+			raw: `/**************************************************************************
+Symbols and macros.
+
+Please preserve this description.
+**************************************************************************/`,
+			want: []string{
+				"// Symbols and macros.",
+				"//",
+				"// Please preserve this description.",
+			},
+		},
+		{
+			name: "bang block comment",
+			raw:  "/*! A documented declaration. */",
+			want: []string{"// A documented declaration."},
+		},
+		{
+			name: "doxygen block comment",
+			raw:  "/**\n * A documented declaration.\n */",
+			want: []string{"// A documented declaration."},
+		},
+		{
+			name: "doxygen line comment",
+			raw:  "/// A documented declaration.",
+			want: []string{"// A documented declaration."},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotComments := toLineComments(tt.raw)
+			got := make([]string, len(gotComments))
+			for i, comment := range gotComments {
+				got[i] = comment.Text
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("toLineComments() = %#v, want %#v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/tool/_testc/python-3.14.8/llcppg.cfg b/tool/_testc/python-3.14.8/llcppg.cfg
index 998886eec..c206f0a2b 100644
--- a/tool/_testc/python-3.14.8/llcppg.cfg
+++ b/tool/_testc/python-3.14.8/llcppg.cfg
@@ -20,5 +20,6 @@
 	"GroupSubdirBy": "fname",
 	"FailFast": 10,
 	"IgnoreInline": true,
+	"KeepDoc": true,
 	"Language": "c"
 }
diff --git a/tool/_testcpp/llvm-22.1.8-support/go.mod b/tool/_testcpp/llvm-22.1.8-support/go.mod
index f01dc51a9..c10378236 100644
--- a/tool/_testcpp/llvm-22.1.8-support/go.mod
+++ b/tool/_testcpp/llvm-22.1.8-support/go.mod
@@ -2,10 +2,6 @@ module llvm
 
 go 1.23
 
-require (
-	github.com/goplus/lib v0.5.9
-	github.com/llarhub/libcxx v0.1.1
-	github.com/llarhub/llvm-c v0.2.0
-)
+require github.com/goplus/lib v0.5.9
 
 require github.com/qiniu/x v1.18.3 // indirect
diff --git a/tool/_testcpp/llvm-22.1.8-support/go.sum b/tool/_testcpp/llvm-22.1.8-support/go.sum
index f279ba905..8b6af0496 100644
--- a/tool/_testcpp/llvm-22.1.8-support/go.sum
+++ b/tool/_testcpp/llvm-22.1.8-support/go.sum
@@ -1,8 +1,4 @@
 github.com/goplus/lib v0.5.9 h1:XTUGEBqzrqMKmN7n+bCsLSq2MxK0pnP+Ea+gjcfBMjM=
 github.com/goplus/lib v0.5.9/go.mod h1:t4Cgs4QYbPzpI1RnYRA0iXWTgUFUuE09TrE2PvuU0VM=
-github.com/llarhub/libcxx v0.1.1 h1:pq/qd3sgtDsima+rrgwOEHYGd/YnyePe6p86rHFD+Xs=
-github.com/llarhub/libcxx v0.1.1/go.mod h1:5ANUOJMknbqPXhwxbXnLLA8NbHHyfYWUVQNCPiz04f8=
-github.com/llarhub/llvm-c v0.2.0 h1:KXSm+1A9AjyxOcVTtZnlgvWDaWwBySMR27xSouaOaGg=
-github.com/llarhub/llvm-c v0.2.0/go.mod h1:5Z6A6u+TghfHdA82zNAhYZHlUkzra7YdUJWc8q3IoJ4=
 github.com/qiniu/x v1.18.3 h1:trrBKBNszHGwV8XynnbddJr+A7Vca8/xlWP4F/Z4my8=
 github.com/qiniu/x v1.18.3/go.mod h1:Sx3Wy+0GI9OsX4a53mYj6A0o7mHJ94PUvraqGYb4EIs=
diff --git a/tool/config.go b/tool/config.go
index 59bc91c71..7c02f2809 100644
--- a/tool/config.go
+++ b/tool/config.go
@@ -56,6 +56,7 @@ type Config struct {
 	Pkgs             []string          `json:"Pkgs"`             // sub-packages to generate, optional
 	FailFast         int               `json:"FailFast"`         // exit on first N errors, optional
 	IgnoreInline     bool              `json:"IgnoreInline"`     // quietly ignore inline functions
+	KeepDoc          bool              `json:"KeepDoc"`          // parse all comments for documentation extraction
 	NoManglingIgnore bool              `json:"NoManglingIgnore"` // quietly ignore functions with no mangled symbol
 	GroupSubdir      bool              `json:"GroupSubdir"`      // treats sub-directory files as a single file. Deprecated: use GroupSubdirBy instead.
 	GroupSubdirBy    string            `json:"GroupSubdirBy"`    // criterion to group sub-directory files by, e.g., "dir" or "fname". `GroupSubdir = true` is equivalent to `GroupSubdirBy = "dir"`.
@@ -91,6 +92,9 @@ func (cfg *Config) Apply(parent *Config) {
 	if cfg.CFlags == "" {
 		cfg.CFlags = parent.CFlags
 	}
+	if !cfg.KeepDoc {
+		cfg.KeepDoc = parent.KeepDoc
+	}
 	if cfg.Deps == nil {
 		cfg.Deps = parent.Deps
 	}
diff --git a/tool/gen.go b/tool/gen.go
index f0de094f9..9f0a76137 100644
--- a/tool/gen.go
+++ b/tool/gen.go
@@ -167,7 +167,7 @@ func (cfg *Config) NewPackage(pkgPath, pkgName, workDir string, index clang.Inde
 		}
 	}
 
-	files, err := ParseSources(index, topHeaders, incDirs, cfg.Language)
+	files, err := ParseSources(index, topHeaders, incDirs, cfg.Language, cfg.KeepDoc)
 	if err != nil {
 		return
 	}
@@ -348,10 +348,12 @@ func ParseFlags(includeDirs []string, lang string) []string {
 }
 
 // ParseSources parses the given source files and returns the translation units corresponding
-// to those files.
-func ParseSources(index clang.Index, headerFiles, includeDirs []string, lang string) ([]cl.Source, error) {
+// to those files. If keepDoc is true, it also parses ordinary comments.
+func ParseSources(index clang.Index, headerFiles, includeDirs []string, lang string, keepDoc ...bool) ([]cl.Source, error) {
 	flags := ParseFlags(includeDirs, lang)
-	flags = append(flags, "-fparse-all-comments")
+	if len(keepDoc) > 0 && keepDoc[0] {
+		flags = append(flags, "-fparse-all-comments")
+	}
 	files := make([]cl.Source, len(headerFiles))
 	for i, headerFile := range headerFiles {
 		tu, e := index.ParseTranslationUnit(clang.DetailedPreprocessingRecord, headerFile, flags...)