diff --git a/lib/Parse/Lexer.cpp b/lib/Parse/Lexer.cpp
index d9f3c70ffddc..195e18a32be4 100644
--- a/lib/Parse/Lexer.cpp
+++ b/lib/Parse/Lexer.cpp
@@ -1379,14 +1379,27 @@ static bool delimiterMatches(unsigned CustomDelimiterLen, const char *&BytesPtr,
 
 /// advanceIfMultilineDelimiter - Centralized check for multiline delimiter.
 static bool advanceIfMultilineDelimiter(unsigned CustomDelimiterLen,
-                                        const char *&CurPtr,
+                                        const char *&CurPtr, const char *EndPtr,
                                         DiagnosticEngine *Diags,
                                         bool IsOpening = false) {
+  auto scanDelimiter = [&]() -> const char * {
+    // CurPtr here points to the character after `"`.
+    const char *TmpPtr = CurPtr;
+    if (*(TmpPtr - 1) == '"' &&
+        diagnoseZeroWidthMatchAndAdvance('"', TmpPtr, Diags) &&
+        diagnoseZeroWidthMatchAndAdvance('"', TmpPtr, Diags)) {
+      return TmpPtr;
+    }
+    return nullptr;
+  };
+  auto *DelimEnd = scanDelimiter();
+  if (!DelimEnd)
+    return false;
 
   // Test for single-line string literals that resemble multiline delimiter.
-  const char *TmpPtr = CurPtr + 1;
+  const char *TmpPtr = DelimEnd - 1;
   if (IsOpening && CustomDelimiterLen) {
-    while (*TmpPtr != '\r' && *TmpPtr != '\n') {
+    while (TmpPtr != EndPtr && *TmpPtr != '\r' && *TmpPtr != '\n') {
       if (*TmpPtr == '"') {
         if (delimiterMatches(CustomDelimiterLen, ++TmpPtr, nullptr)) {
           return false;
@@ -1397,15 +1410,8 @@ static bool advanceIfMultilineDelimiter(unsigned CustomDelimiterLen,
     }
   }
 
-  TmpPtr = CurPtr;
-  if (*(TmpPtr - 1) == '"' &&
-      diagnoseZeroWidthMatchAndAdvance('"', TmpPtr, Diags) &&
-      diagnoseZeroWidthMatchAndAdvance('"', TmpPtr, Diags)) {
-    CurPtr = TmpPtr;
-    return true;
-  }
-
-  return false;
+  CurPtr = DelimEnd;
+  return true;
 }
 
 /// lexCharacter - Read a character and return its UTF32 code.  If this is the
@@ -1450,8 +1456,8 @@ unsigned Lexer::lexCharacter(const char *&CurPtr, char StopQuote,
 
       DiagnosticEngine *D = EmitDiagnostics ? getTokenDiags() : nullptr;
       auto TmpPtr = CurPtr;
-      if (IsMultilineString &&
-          !advanceIfMultilineDelimiter(CustomDelimiterLen, TmpPtr, D))
+      if (IsMultilineString && !advanceIfMultilineDelimiter(
+                                   CustomDelimiterLen, TmpPtr, BufferEnd, D))
         return '"';
       if (CustomDelimiterLen &&
           !delimiterMatches(CustomDelimiterLen, TmpPtr, D, /*IsClosing=*/true))
@@ -1587,9 +1593,8 @@ static const char *skipToEndOfInterpolatedExpression(const char *CurPtr,
       if (!inStringLiteral()) {
         // Open string literal.
         OpenDelimiters.push_back(CurPtr[-1]);
-        AllowNewline.push_back(advanceIfMultilineDelimiter(CustomDelimiterLen,
-                                                           CurPtr, nullptr,
-                                                           true));
+        AllowNewline.push_back(advanceIfMultilineDelimiter(
+            CustomDelimiterLen, CurPtr, EndPtr, nullptr, true));
         CustomDelimiter.push_back(CustomDelimiterLen);
         continue;
       }
@@ -1602,7 +1607,8 @@ static const char *skipToEndOfInterpolatedExpression(const char *CurPtr,
 
       // Multi-line string can only be closed by '"""'.
       if (AllowNewline.back() &&
-          !advanceIfMultilineDelimiter(CustomDelimiterLen, CurPtr, nullptr))
+          !advanceIfMultilineDelimiter(CustomDelimiterLen, CurPtr, EndPtr,
+                                       nullptr))
         continue;
 
       // Check whether we have equivalent number of '#'s.
@@ -1947,7 +1953,7 @@ void Lexer::lexStringLiteral(unsigned CustomDelimiterLen) {
   assert((QuoteChar == '"' || QuoteChar == '\'') && "Unexpected start");
 
   bool IsMultilineString = advanceIfMultilineDelimiter(
-      CustomDelimiterLen, CurPtr, getTokenDiags(), true);
+      CustomDelimiterLen, CurPtr, BufferEnd, getTokenDiags(), true);
   if (IsMultilineString && *CurPtr != '\n' && *CurPtr != '\r')
     diagnose(CurPtr, diag::lex_illegal_multiline_string_start)
         .fixItInsert(Lexer::getSourceLoc(CurPtr), "\n");
diff --git a/validation-test/compiler_crashers_fixed/Parser-consumeTokenWithoutFeedingReceiver-dff2d1.swift b/validation-test/compiler_crashers_fixed/Parser-consumeTokenWithoutFeedingReceiver-dff2d1.swift
new file mode 100644
index 000000000000..f5b614d05820
--- /dev/null
+++ b/validation-test/compiler_crashers_fixed/Parser-consumeTokenWithoutFeedingReceiver-dff2d1.swift
@@ -0,0 +1,10 @@
+// RUN: %empty-directory(%t)
+
+// RUN: echo '#"' > %t/main1.swift
+// RUN: echo -n '#"' > %t/main2.swift
+
+// RUN: env DYLD_INSERT_LIBRARIES=/usr/lib/libgmalloc.dylib not %target-swift-frontend -typecheck %t/main1.swift
+// RUN: env DYLD_INSERT_LIBRARIES=/usr/lib/libgmalloc.dylib not %target-swift-frontend -typecheck %t/main2.swift
+
+// guardmalloc is incompatible with ASAN
+// REQUIRES: no_asan