Index: llvm/lib/Support/YAMLParser.cpp
===================================================================
--- llvm/lib/Support/YAMLParser.cpp
+++ llvm/lib/Support/YAMLParser.cpp
@@ -2269,8 +2269,8 @@
 bool Document::skip()  {
   if (stream.scanner->failed())
     return false;
-  if (!Root)
-    getRoot();
+  if (!Root && !getRoot())
+    return false;
   Root->skip();
   Token &T = peekNext();
   if (T.Kind == Token::TK_StreamEnd)
@@ -2395,8 +2395,12 @@
     //       !!null null.
     return new (NodeAllocator) NullNode(stream.CurrentDoc);
   case Token::TK_Error:
+  case Token::TK_FlowEntry:
+  case Token::TK_FlowMappingEnd:
+  case Token::TK_FlowSequenceEnd: {
     return nullptr;
   }
+  }
   llvm_unreachable("Control flow shouldn't reach here.");
   return nullptr;
 }
Index: llvm/unittests/Support/YAMLParserTest.cpp
===================================================================
--- llvm/unittests/Support/YAMLParserTest.cpp
+++ llvm/unittests/Support/YAMLParserTest.cpp
@@ -331,4 +331,15 @@
   EXPECT_TRUE(End == AnotherEnd);
 }
 
+TEST(YAMLParser, FlowSequenceTokensOutsideFlowSequence) {
+  auto FlowSequenceStrs = {",", "]", "}"};
+  SourceMgr SM;
+
+  for (auto &Str : FlowSequenceStrs) {
+    yaml::Stream Stream(Str, SM);
+    yaml::Document &Doc = *Stream.begin();
+    EXPECT_FALSE(Doc.skip());
+  }
+}
+
 } // end namespace llvm