diff --git a/clang/lib/Tooling/Syntax/BuildTree.cpp b/clang/lib/Tooling/Syntax/BuildTree.cpp
--- a/clang/lib/Tooling/Syntax/BuildTree.cpp
+++ b/clang/lib/Tooling/Syntax/BuildTree.cpp
@@ -856,6 +856,11 @@
     return RecursiveASTVisitor::TraverseStmt(S);
   }
 
+  bool TraverseOpaqueValueExpr(OpaqueValueExpr *VE) {
+    // OpaqueValue doesn't correspond to concrete syntax, ignore it.
+    return true;
+  }
+
   // Some expressions are not yet handled by syntax trees.
   bool WalkUpFromExpr(Expr *E) {
     assert(!isImplicitExpr(E) && "should be handled by TraverseStmt");
diff --git a/clang/unittests/Tooling/Syntax/BuildTreeTest.cpp b/clang/unittests/Tooling/Syntax/BuildTreeTest.cpp
--- a/clang/unittests/Tooling/Syntax/BuildTreeTest.cpp
+++ b/clang/unittests/Tooling/Syntax/BuildTreeTest.cpp
@@ -512,6 +512,25 @@
 )txt"));
 }
 
+TEST_P(BuildSyntaxTreeTest, ConditionalOperator) {
+  // FIXME: conditional expression is not modeled yet.
+  EXPECT_TRUE(treeDumpEqualOnAnnotations(
+      R"cpp(
+void test() {
+  [[1?:2]];
+}
+)cpp",
+      {R"txt(
+UnknownExpression Expression
+|-IntegerLiteralExpression
+| `-'1' LiteralToken
+|-'?'
+|-':'
+`-IntegerLiteralExpression
+  `-'2' LiteralToken
+)txt"}));
+}
+
 TEST_P(BuildSyntaxTreeTest, UnqualifiedId_Identifier) {
   EXPECT_TRUE(treeDumpEqualOnAnnotations(
       R"cpp(