diff --git a/clang-tools-extra/clang-doc/JSONGenerator.cpp b/clang-tools-extra/clang-doc/JSONGenerator.cpp
index 58995c249bd2..b4284f8eb4d1 100644
--- a/clang-tools-extra/clang-doc/JSONGenerator.cpp
+++ b/clang-tools-extra/clang-doc/JSONGenerator.cpp
@@ -106,6 +106,12 @@ static void insertNonEmpty(StringRef Key, StringRef Value, Object &Obj) {
     Obj[Key] = Value;
 }
 
+static json::Value safeJSONString(StringRef S) {
+  if (LLVM_LIKELY(json::isUTF8(S)))
+    return S;
+  return json::fixUTF8(S);
+}
+
 static std::string infoTypeToString(InfoType IT) {
   switch (IT) {
   case InfoType::IT_default:
@@ -233,7 +239,7 @@ static Object serializeComment(const CommentInfo &I, Object &Description) {
   switch (I.Kind) {
   case CommentKind::CK_TextComment: {
     if (!I.Text.empty())
-      Obj.insert({commentKindToString(I.Kind), I.Text});
+      Obj.insert({commentKindToString(I.Kind), safeJSONString(I.Text)});
     return Obj;
   }
 
@@ -258,7 +264,7 @@ static Object serializeComment(const CommentInfo &I, Object &Description) {
     auto &ARef = *ArgsArr.getAsArray();
     ARef.reserve(I.Args.size());
     for (const auto &Arg : I.Args)
-      ARef.emplace_back(Arg);
+      ARef.emplace_back(safeJSONString(Arg));
     Child.insert({"Command", I.Name});
     Child.insert({"Args", ArgsArr});
     Child.insert({"Children", ChildArr});
@@ -292,7 +298,7 @@ static Object serializeComment(const CommentInfo &I, Object &Description) {
 
   case CommentKind::CK_VerbatimBlockLineComment:
   case CommentKind::CK_VerbatimLineComment: {
-    Child.insert({"Text", I.Text});
+    Child.insert({"Text", safeJSONString(I.Text)});
     Child.insert({"Children", ChildArr});
     Obj.insert({commentKindToString(I.Kind), ChildVal});
     return Obj;
@@ -333,7 +339,7 @@ static Object serializeComment(const CommentInfo &I, Object &Description) {
   }
 
   case CommentKind::CK_Unknown: {
-    Obj.insert({commentKindToString(I.Kind), I.Text});
+    Obj.insert({commentKindToString(I.Kind), safeJSONString(I.Text)});
     return Obj;
   }
   }
diff --git a/clang-tools-extra/test/clang-doc/Inputs/invalid-utf8-comment.cpp b/clang-tools-extra/test/clang-doc/Inputs/invalid-utf8-comment.cpp
new file mode 100644
index 000000000000..89f3ff437819
--- /dev/null
+++ b/clang-tools-extra/test/clang-doc/Inputs/invalid-utf8-comment.cpp
@@ -0,0 +1,2 @@
+// non-UTF-8: �
+class A {};
diff --git a/clang-tools-extra/test/clang-doc/json/invalid-utf8-comment.cpp b/clang-tools-extra/test/clang-doc/json/invalid-utf8-comment.cpp
new file mode 100644
index 000000000000..b2bd4174832d
--- /dev/null
+++ b/clang-tools-extra/test/clang-doc/json/invalid-utf8-comment.cpp
@@ -0,0 +1,46 @@
+// RUN: rm -rf %t && mkdir -p %t
+// RUN: clang-doc --pretty-json --output=%t --format=json --executor=standalone %S/../Inputs/invalid-utf8-comment.cpp 2>&1
+// RUN: cat %t/json/GlobalNamespace/_ZTV1A.json | FileCheck %s
+
+// Regression test for https://github.com/llvm/llvm-project/issues/210675.
+// clang-doc should not crash when encountering comments with invalid UTF-8 bytes.
+// Instead, the invalid bytes should be replaced with valid UTF-8 replacement characters.
+
+// CHECK:       {
+// CHECK-NEXT:    "Contexts": [
+// CHECK-NEXT:      {
+// CHECK-NEXT:        "DocumentationFileName": "index",
+// CHECK-NEXT:        "End": true,
+// CHECK-NEXT:        "Name": "Global Namespace",
+// CHECK-NEXT:        "QualName": "GlobalNamespace",
+// CHECK-NEXT:        "RelativePath": "./",
+// CHECK-NEXT:        "USR": "0000000000000000000000000000000000000000"
+// CHECK-NEXT:      }
+// CHECK-NEXT:    ],
+// CHECK-NEXT:    "Description": {
+// CHECK-NEXT:      "HasParagraphComments": true,
+// CHECK-NEXT:      "ParagraphComments": [
+// CHECK-NEXT:        [
+// CHECK-NEXT:          {
+// CHECK:               "TextComment":
+// CHECK-NEXT:          }
+// CHECK-NEXT:        ]
+// CHECK-NEXT:      ]
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "DocumentationFileName": "_ZTV1A",
+// CHECK-NEXT:    "HasContexts": true,
+// CHECK-NEXT:    "InfoType": "record",
+// CHECK-NEXT:    "IsTypedef": false,
+// CHECK-NEXT:    "Location": {
+// CHECK-NEXT:      "Filename": "{{.*}}invalid-utf8-comment.cpp",
+// CHECK-NEXT:      "LineNumber": 2
+// CHECK-NEXT:    },
+// CHECK-NEXT:    "MangledName": "_ZTV1A",
+// CHECK-NEXT:    "Name": "A",
+// CHECK-NEXT:    "Namespace": [
+// CHECK-NEXT:      "GlobalNamespace"
+// CHECK-NEXT:    ],
+// CHECK-NEXT:    "Path": "GlobalNamespace",
+// CHECK-NEXT:    "TagType": "class",
+// CHECK-NEXT:    "USR": "{{[0-9A-F]*}}"
+// CHECK-NEXT:  }