Index: lib/Support/YAMLTraits.cpp
===================================================================
--- lib/Support/YAMLTraits.cpp
+++ lib/Support/YAMLTraits.cpp
@@ -112,7 +112,7 @@
 }
 
 void Input::beginMapping() {
-  if (EC)
+  if (EC || Strm->failed())
     return;
   // CurrentNode can be null if the document is empty.
   MapHNode *MN = dyn_cast_or_null<MapHNode>(CurrentNode);
@@ -124,7 +124,7 @@
 bool Input::preflightKey(const char *Key, bool Required, bool, bool &UseDefault,
                          void *&SaveInfo) {
   UseDefault = false;
-  if (EC)
+  if (EC || Strm->failed())
     return false;
 
   // CurrentNode is null for empty documents, which is an error in case required
@@ -159,7 +159,7 @@
 }
 
 void Input::endMapping() {
-  if (EC)
+  if (EC || Strm->failed())
     return;
   // CurrentNode can be null if the document is empty.
   MapHNode *MN = dyn_cast_or_null<MapHNode>(CurrentNode);
@@ -196,7 +196,7 @@
 }
 
 bool Input::preflightElement(unsigned Index, void *&SaveInfo) {
-  if (EC)
+  if (EC || Strm->failed())
     return false;
   if (SequenceHNode *SQ = dyn_cast<SequenceHNode>(CurrentNode)) {
     SaveInfo = CurrentNode;
@@ -213,7 +213,7 @@
 unsigned Input::beginFlowSequence() { return beginSequence(); }
 
 bool Input::preflightFlowElement(unsigned index, void *&SaveInfo) {
-  if (EC)
+  if (EC || Strm->failed())
     return false;
   if (SequenceHNode *SQ = dyn_cast<SequenceHNode>(CurrentNode)) {
     SaveInfo = CurrentNode;
@@ -271,7 +271,7 @@
 }
 
 bool Input::bitSetMatch(const char *Str, bool) {
-  if (EC)
+  if (EC || Strm->failed())
     return false;
   if (SequenceHNode *SQ = dyn_cast<SequenceHNode>(CurrentNode)) {
     unsigned Index = 0;
@@ -293,7 +293,7 @@
 }
 
 void Input::endBitSetScalar() {
-  if (EC)
+  if (EC || Strm->failed())
     return;
   if (SequenceHNode *SQ = dyn_cast<SequenceHNode>(CurrentNode)) {
     assert(BitValuesUsed.size() == SQ->Entries.size());
@@ -342,7 +342,7 @@
     auto SQHNode = llvm::make_unique<SequenceHNode>(N);
     for (Node &SN : *SQ) {
       auto Entry = this->createHNodes(&SN);
-      if (EC)
+      if (EC || Strm->failed())
         break;
       SQHNode->Entries.push_back(std::move(Entry));
     }
@@ -363,7 +363,7 @@
         KeyStr = StringStorage.str().copy(StringAllocator);
       }
       auto ValueHNode = this->createHNodes(KVN.getValue());
-      if (EC)
+      if (EC || Strm->failed())
         break;
       mapHNode->Mapping[KeyStr] = std::move(ValueHNode);
     }
Index: unittests/Support/YAMLIOTest.cpp
===================================================================
--- unittests/Support/YAMLIOTest.cpp
+++ unittests/Support/YAMLIOTest.cpp
@@ -2368,3 +2368,11 @@
             out);
   out.clear();
 }
+
+TEST(YAMLIO, InvalidInput) {
+  // polluting 1 value in the sequence
+  Input yin("---\n- foo:  3\n  bar:  5\n1\n- foo:  3\n  bar:  5\n...\n");
+  std::vector<FooBar> Data;
+  yin >> Data;
+  EXPECT_TRUE((bool)yin.error());
+}