diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1201,7 +1201,7 @@
   MarshallingInfoFlag<"DiagnosticOpts->UseANSIEscapeCodes">;
 def fcomment_block_commands : CommaJoined<["-"], "fcomment-block-commands=">, Group<f_clang_Group>, Flags<[CC1Option]>,
   HelpText<"Treat each comma separated argument in <arg> as a documentation comment block command">,
-  MetaVarName<"<arg>">;
+  MetaVarName<"<arg>">, MarshallingInfoStringVector<"LangOpts->CommentOpts.BlockCommandNames">;
 def fparse_all_comments : Flag<["-"], "fparse-all-comments">, Group<f_clang_Group>, Flags<[CC1Option]>,
   MarshallingInfoFlag<"LangOpts->CommentOpts.ParseAllComments">;
 def frecord_command_line : Flag<["-"], "frecord-command-line">,
diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -328,8 +328,20 @@
                                     Option::OptionClass OptClass,
                                     unsigned TableIndex,
                                     const std::vector<std::string> &Values) {
-  for (const std::string &Value : Values) {
-    denormalizeString(Args, Spelling, SA, OptClass, TableIndex, Value);
+  if (OptClass == Option::OptionClass::CommaJoinedClass) {
+    std::string CommaJoinedValue;
+    if (!Values.empty()) {
+      CommaJoinedValue.append(Values.front());
+      for (const std::string &Value : llvm::drop_begin(Values, 1)) {
+        CommaJoinedValue.append(",");
+        CommaJoinedValue.append(Value);
+      }
+    }
+    denormalizeString(Args, Spelling, SA, Option::OptionClass::JoinedClass,
+                      TableIndex, CommaJoinedValue);
+  } else if (OptClass == Option::OptionClass::JoinedClass) {
+    for (const std::string &Value : Values)
+      denormalizeString(Args, Spelling, SA, OptClass, TableIndex, Value);
   }
 }
 
@@ -785,7 +797,6 @@
 }
 
 static void ParseCommentArgs(CommentOptions &Opts, ArgList &Args) {
-  Opts.BlockCommandNames = Args.getAllArgValues(OPT_fcomment_block_commands);
   Opts.ParseAllComments = Args.hasArg(OPT_fparse_all_comments);
 }
 
diff --git a/clang/unittests/Frontend/CompilerInvocationTest.cpp b/clang/unittests/Frontend/CompilerInvocationTest.cpp
--- a/clang/unittests/Frontend/CompilerInvocationTest.cpp
+++ b/clang/unittests/Frontend/CompilerInvocationTest.cpp
@@ -508,6 +508,53 @@
   ASSERT_THAT(GeneratedArgs, ContainsN(HasSubstr("-fmodule-map-file"), 2));
 }
 
+// CommaJoined option with MarshallingInfoStringVector.
+
+TEST_F(CommandLineTest, StringVectorCommaJoinedNone) {
+  const char *Args[] = {""};
+
+  CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags);
+
+  ASSERT_FALSE(Diags->hasErrorOccurred());
+  ASSERT_TRUE(Invocation.getLangOpts()->CommentOpts.BlockCommandNames.empty());
+
+  Invocation.generateCC1CommandLine(GeneratedArgs, *this);
+
+  ASSERT_THAT(GeneratedArgs,
+              Not(Contains(HasSubstr("-fcomment-block-commands"))));
+}
+
+TEST_F(CommandLineTest, StringVectorCommaJoinedSingle) {
+  const char *Args[] = {"-fcomment-block-commands=x,y"};
+
+  CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags);
+
+  ASSERT_FALSE(Diags->hasErrorOccurred());
+  ASSERT_EQ(Invocation.getLangOpts()->CommentOpts.BlockCommandNames,
+            std::vector<std::string>({"x", "y"}));
+
+  Invocation.generateCC1CommandLine(GeneratedArgs, *this);
+
+  ASSERT_THAT(GeneratedArgs,
+              ContainsN(StrEq("-fcomment-block-commands=x,y"), 1));
+}
+
+TEST_F(CommandLineTest, StringVectorCommaJoinedMultiple) {
+  const char *Args[] = {"-fcomment-block-commands=x,y",
+                        "-fcomment-block-commands=a,b"};
+
+  CompilerInvocation::CreateFromArgs(Invocation, Args, *Diags);
+
+  ASSERT_FALSE(Diags->hasErrorOccurred());
+  ASSERT_EQ(Invocation.getLangOpts()->CommentOpts.BlockCommandNames,
+            std::vector<std::string>({"x", "y", "a", "b"}));
+
+  Invocation.generateCC1CommandLine(GeneratedArgs, *this);
+
+  ASSERT_THAT(GeneratedArgs,
+              ContainsN(StrEq("-fcomment-block-commands=x,y,a,b"), 1));
+}
+
 // A flag that should be parsed only if a condition is met.
 
 TEST_F(CommandLineTest, ConditionalParsingIfFalseFlagNotPresent) {