Index: clang-query/QueryParser.cpp
===================================================================
--- clang-query/QueryParser.cpp
+++ clang-query/QueryParser.cpp
@@ -37,6 +37,11 @@
     ++Begin;
   }
 
+  if (*Begin == '#') {
+    End = Begin;
+    return StringRef();
+  }
+
   const char *WordBegin = Begin;
 
   while (true) {
@@ -127,6 +132,7 @@
 
 enum ParsedQueryKind {
   PQK_Invalid,
+  PQK_Comment,
   PQK_NoOp,
   PQK_Help,
   PQK_Let,
@@ -161,6 +167,7 @@
   StringRef CommandStr;
   ParsedQueryKind QKind = LexOrCompleteWord<ParsedQueryKind>(this, CommandStr)
                               .Case("", PQK_NoOp)
+                              .Case("#", PQK_Comment, /*IsCompletion=*/false)
                               .Case("help", PQK_Help)
                               .Case("l", PQK_Let, /*IsCompletion=*/false)
                               .Case("let", PQK_Let)
@@ -173,6 +180,7 @@
                               .Default(PQK_Invalid);
 
   switch (QKind) {
+  case PQK_Comment:
   case PQK_NoOp:
     return new NoOpQuery;
 
Index: unittests/clang-query/QueryParserTest.cpp
===================================================================
--- unittests/clang-query/QueryParserTest.cpp
+++ unittests/clang-query/QueryParserTest.cpp
@@ -146,6 +146,17 @@
             cast<InvalidQuery>(Q)->ErrStr);
 }
 
+TEST_F(QueryParserTest, Comment) {
+  QueryRef Q = parse("# let foo decl()");
+  ASSERT_TRUE(isa<NoOpQuery>(Q));
+
+  Q = parse("let foo decl() # creates a decl() matcher called foo");
+  ASSERT_TRUE(isa<LetQuery>(Q));
+
+  Q = parse("set bind-root false # reduce noise");
+  ASSERT_TRUE(isa<SetQuery<bool>>(Q));
+}
+
 TEST_F(QueryParserTest, Complete) {
   std::vector<llvm::LineEditor::Completion> Comps =
       QueryParser::complete("", 0, QS);