diff --git a/llvm/include/llvm/Support/FileCheck.h b/llvm/include/llvm/Support/FileCheck.h
--- a/llvm/include/llvm/Support/FileCheck.h
+++ b/llvm/include/llvm/Support/FileCheck.h
@@ -103,6 +103,8 @@
   /// (MatchFoundAndExpected) or a failure to match (MatchNoneButExpected),
   /// and there might be a fuzzy match (MatchFuzzy) after the latter.
   enum MatchType {
+    /// Indicates an error during match.
+    MatchError,
     /// Indicates a good match for an expected pattern.
     MatchFoundAndExpected,
     /// Indicates a match for an excluded pattern.
diff --git a/llvm/lib/Support/FileCheck.cpp b/llvm/lib/Support/FileCheck.cpp
--- a/llvm/lib/Support/FileCheck.cpp
+++ b/llvm/lib/Support/FileCheck.cpp
@@ -1165,7 +1165,7 @@
       Expected<std::string> Value = Substitution->getResult();
       if (!Value) {
         // Convert to an ErrorDiagnostic to get location information. This is
-        // done here rather than PrintNoMatch since now we know which
+        // done here rather than printNoMatch since now we know which
         // substitution block caused the overflow.
         Error Err =
             handleErrors(Value.takeError(), [&](const OverflowError &E) {
@@ -1256,6 +1256,7 @@
     for (const auto &Substitution : Substitutions) {
       SmallString<256> Msg;
       raw_svector_ostream OS(Msg);
+      SourceMgr::DiagKind Kind;
       Expected<std::string> MatchedValue = Substitution->getResult();
 
       // Substitution failed or is not known at match time, print the undefined
@@ -1264,13 +1265,14 @@
         bool UndefSeen = false;
         handleAllErrors(
             MatchedValue.takeError(), [](const NotFoundError &E) {},
-            // Handled in PrintNoMatch().
+            // Handled in printNoMatch().
             [](const ErrorDiagnostic &E) {},
             // Handled in match().
             [](const OverflowError &E) {},
             [&](const UndefVarError &E) {
               if (!UndefSeen) {
                 OS << "uses undefined variable(s):";
+                Kind = SourceMgr::DK_Error;
                 UndefSeen = true;
               }
               OS << " ";
@@ -1278,6 +1280,7 @@
             });
       } else {
         // Substitution succeeded. Print substituted value.
+        Kind = SourceMgr::DK_Note;
         OS << "with \"";
         OS.write_escaped(Substitution->getFromString()) << "\" equal to \"";
         OS.write_escaped(*MatchedValue) << "\"";
@@ -1291,7 +1294,7 @@
         Diags->emplace_back(SM, CheckTy, getLoc(), MatchTy,
                             SMRange(Range.Start, Range.Start), OS.str());
       else
-        SM.PrintMessage(Range.Start, SourceMgr::DK_Note, OS.str());
+        SM.PrintMessage(Range.Start, Kind, OS.str());
     }
   }
 }
@@ -1957,17 +1960,25 @@
              MatchedCount, Buffer, MatchPos, MatchLen, Req, Diags);
 }
 
-static void PrintNoMatch(bool ExpectedMatch, const SourceMgr &SM,
+/// Print and record diagnostics about the failure to match the input. \returns
+/// true if the failure was due to a match error.
+static bool printNoMatch(bool ExpectedMatch, const SourceMgr &SM,
                          StringRef Prefix, SMLoc Loc, const Pattern &Pat,
                          int MatchedCount, StringRef Buffer,
                          bool VerboseVerbose, std::vector<FileCheckDiag> *Diags,
                          Error MatchErrors) {
   assert(MatchErrors && "Called on successful match");
   bool PrintDiag = true;
-  if (!ExpectedMatch) {
+  bool UndefVar = false;
+
+  MatchErrors =
+      handleErrors(std::move(MatchErrors),
+                   [&](std::unique_ptr<UndefVarError> E) { UndefVar = true; });
+
+  if (!ExpectedMatch && !UndefVar) {
     if (!VerboseVerbose) {
       consumeError(std::move(MatchErrors));
-      return;
+      return false;
     }
     // Due to their verbosity, we don't print verbose diagnostics here if we're
     // gathering them for a different rendering, but we always print other
@@ -1978,51 +1989,62 @@
   // If the current position is at the end of a line, advance to the start of
   // the next line.
   Buffer = Buffer.substr(Buffer.find_first_not_of(" \t\n\r"));
-  FileCheckDiag::MatchType MatchTy = ExpectedMatch
-                                         ? FileCheckDiag::MatchNoneButExpected
-                                         : FileCheckDiag::MatchNoneAndExcluded;
+  FileCheckDiag::MatchType MatchTy;
+  if (UndefVar)
+    MatchTy = FileCheckDiag::MatchError;
+  else if (ExpectedMatch)
+    MatchTy = FileCheckDiag::MatchNoneButExpected;
+  else
+    MatchTy = FileCheckDiag::MatchNoneAndExcluded;
   SMRange SearchRange = ProcessMatchResult(MatchTy, SM, Loc, Pat.getCheckTy(),
                                            Buffer, 0, Buffer.size(), Diags);
   if (Diags)
     Pat.printSubstitutions(SM, Buffer, SearchRange, MatchTy, Diags);
   if (!PrintDiag) {
     consumeError(std::move(MatchErrors));
-    return;
+    return UndefVar;
   }
 
   MatchErrors = handleErrors(std::move(MatchErrors),
                              [](const ErrorDiagnostic &E) { E.log(errs()); });
 
   // No problem matching the string per se.
-  if (!MatchErrors)
-    return;
+  if (!MatchErrors && !UndefVar)
+    return false;
   consumeError(std::move(MatchErrors));
 
-  // Print "not found" diagnostic.
-  std::string Message = formatv("{0}: {1} string not found in input",
-                                Pat.getCheckTy().getDescription(Prefix),
-                                (ExpectedMatch ? "expected" : "excluded"))
-                            .str();
-  if (Pat.getCount() > 1)
-    Message += formatv(" ({0} out of {1})", MatchedCount, Pat.getCount()).str();
-  SM.PrintMessage(
-      Loc, ExpectedMatch ? SourceMgr::DK_Error : SourceMgr::DK_Remark, Message);
+  if (!UndefVar) {
+    // Print "not found" diagnostic.
+    std::string Message = formatv("{0}: {1} string not found in input",
+                                  Pat.getCheckTy().getDescription(Prefix),
+                                  (ExpectedMatch ? "expected" : "excluded"))
+                              .str();
+    if (Pat.getCount() > 1)
+      Message +=
+          formatv(" ({0} out of {1})", MatchedCount, Pat.getCount()).str();
+    SM.PrintMessage(Loc,
+                    ExpectedMatch ? SourceMgr::DK_Error : SourceMgr::DK_Remark,
+                    Message);
 
-  // Print the "scanning from here" line.
-  SM.PrintMessage(SearchRange.Start, SourceMgr::DK_Note, "scanning from here");
+    // Print the "scanning from here" line.
+    SM.PrintMessage(SearchRange.Start, SourceMgr::DK_Note,
+                    "scanning from here");
+  }
 
   // Allow the pattern to print additional information if desired.
   Pat.printSubstitutions(SM, Buffer, SearchRange, MatchTy, nullptr);
 
-  if (ExpectedMatch)
+  if (ExpectedMatch && !UndefVar)
     Pat.printFuzzyMatch(SM, Buffer, Diags);
+
+  return UndefVar;
 }
 
 static void PrintNoMatch(bool ExpectedMatch, const SourceMgr &SM,
                          const FileCheckString &CheckStr, int MatchedCount,
                          StringRef Buffer, bool VerboseVerbose,
                          std::vector<FileCheckDiag> *Diags, Error MatchErrors) {
-  PrintNoMatch(ExpectedMatch, SM, CheckStr.Prefix, CheckStr.Loc, CheckStr.Pat,
+  printNoMatch(ExpectedMatch, SM, CheckStr.Prefix, CheckStr.Loc, CheckStr.Pat,
                MatchedCount, Buffer, VerboseVerbose, Diags,
                std::move(MatchErrors));
 }
@@ -2197,6 +2219,7 @@
                                const std::vector<const Pattern *> &NotStrings,
                                const FileCheckRequest &Req,
                                std::vector<FileCheckDiag> *Diags) const {
+  bool DirectiveFail = false;
   for (const Pattern *Pat : NotStrings) {
     assert((Pat->getCheckTy() == Check::CheckNot) && "Expect CHECK-NOT!");
 
@@ -2204,19 +2227,20 @@
     Expected<size_t> MatchResult = Pat->match(Buffer, MatchLen, SM);
 
     if (!MatchResult) {
-      PrintNoMatch(false, SM, Prefix, Pat->getLoc(), *Pat, 1, Buffer,
-                   Req.VerboseVerbose, Diags, MatchResult.takeError());
+      if (printNoMatch(false, SM, Prefix, Pat->getLoc(), *Pat, 1, Buffer,
+                       Req.VerboseVerbose, Diags, MatchResult.takeError()))
+        DirectiveFail = true;
       continue;
     }
     size_t Pos = *MatchResult;
 
     PrintMatch(false, SM, Prefix, Pat->getLoc(), *Pat, 1, Buffer, Pos, MatchLen,
                Req, Diags);
-
-    return true;
+    DirectiveFail = true;
+    continue;
   }
 
-  return false;
+  return DirectiveFail;
 }
 
 size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
@@ -2265,7 +2289,7 @@
       // With a group of CHECK-DAGs, a single mismatching means the match on
       // that group of CHECK-DAGs fails immediately.
       if (!MatchResult) {
-        PrintNoMatch(true, SM, Prefix, Pat.getLoc(), Pat, 1, MatchBuffer,
+        printNoMatch(true, SM, Prefix, Pat.getLoc(), Pat, 1, MatchBuffer,
                      Req.VerboseVerbose, Diags, MatchResult.takeError());
         return StringRef::npos;
       }
diff --git a/llvm/test/FileCheck/dump-input-annotations.txt b/llvm/test/FileCheck/dump-input-annotations.txt
--- a/llvm/test/FileCheck/dump-input-annotations.txt
+++ b/llvm/test/FileCheck/dump-input-annotations.txt
@@ -622,11 +622,10 @@
 ; SUBST-POS-NEXT:check:1'1                           with "DEF_MATCH1" equal to "def-match1"
 ; SUBST-POS-NEXT:check:1'2                           with "DEF_MATCH2" equal to "def-match2"
 ; SUBST-POS-NEXT:           2: def-match1 def-nomatch
-; SUBST-POS-NEXT:check:2'0     X~~~~~~~~~~~~~~~~~~~~~ error: no match found
+; SUBST-POS-NEXT:check:2'0     X~~~~~~~~~~~~~~~~~~~~~ error: match error
 ; SUBST-POS-NEXT:check:2'1                            with "DEF_MATCH1" equal to "def-match1"
 ; SUBST-POS-NEXT:check:2'2                            uses undefined variable(s): "UNDEF"
 ; SUBST-POS-NEXT:check:2'3                            with "DEF_NOMATCH" equal to "foobar"
-; SUBST-POS-NEXT:check:2'4              ?             possible intended match
 ; SUBST-POS-NEXT:>>>>>>
 
 ;--------------------------------------------------
@@ -654,7 +653,7 @@
 
 ;      SUBST-NEG:<<<<<<
 ; SUBST-NEG-NEXT:         1: def-match1 def-nomatch
-; SUBST-NEG-NEXT:not:1'0     X~~~~~~~~~~~~~~~~~~~~~
+; SUBST-NEG-NEXT:not:1'0     X~~~~~~~~~~~~~~~~~~~~~ error: match error
 ; SUBST-NEG-NEXT:not:1'1                            with "DEF_MATCH1" equal to "def-match1"
 ; SUBST-NEG-NEXT:not:1'2                            uses undefined variable(s): "UNDEF"
 ; SUBST-NEG-NEXT:not:1'3                            with "DEF_NOMATCH" equal to "foobar"
diff --git a/llvm/test/FileCheck/numeric-expression.txt b/llvm/test/FileCheck/numeric-expression.txt
--- a/llvm/test/FileCheck/numeric-expression.txt
+++ b/llvm/test/FileCheck/numeric-expression.txt
@@ -165,7 +165,7 @@
 ; Numeric expressions in default matching format and explicit matching rule using
 ; variable defined on other lines with match failure.
 RUN: %ProtectFileCheckOutput \
-RUN: not FileCheck --check-prefix NUMEXPR-CONSTRAINT-NOMATCH --input-file %s %s 2>&1 \
+RUN: not FileCheck --check-prefixes CHECK,NUMEXPR-CONSTRAINT-NOMATCH --input-file %s %s 2>&1 \
 RUN:   | FileCheck --check-prefix NUMEXPR-CONSTRAINT-NOMATCH-MSG --strict-whitespace %s
 
 USE DEF FMT EXPL NO MATCH
@@ -282,16 +282,24 @@
 UNDEFVAR: 11
 UNDEF-USE-LABEL: UNDEF VAR USE
 UNDEF-USE-NEXT: UNDEFVAR: [[#UNDEFVAR1+UNDEFVAR2]]
-UNDEF-USE-MSG: numeric-expression.txt:[[#@LINE-1]]:17: error: {{U}}NDEF-USE-NEXT: expected string not found in input
-UNDEF-USE-MSG-NEXT:      {{U}}NDEF-USE-NEXT: UNDEFVAR: {{\[\[#UNDEFVAR1\+UNDEFVAR2\]\]}}
-UNDEF-USE-MSG-NEXT:     {{^}}                ^{{$}}
-UNDEF-USE-MSG-NEXT:      numeric-expression.txt:[[#@LINE-6]]:1: note: scanning from here
-UNDEF-USE-MSG-NEXT:      UNDEFVAR: 11
-UNDEF-USE-MSG-NEXT: {{^}}^{{$}}
-UNDEF-USE-MSG-NEXT:      numeric-expression.txt:[[#@LINE-9]]:1: note: uses undefined variable(s): "UNDEFVAR1" "UNDEFVAR2"
+UNDEF-USE-MSG:      numeric-expression.txt:[[#@LINE-3]]:1: error: uses undefined variable(s): "UNDEFVAR1" "UNDEFVAR2"
 UNDEF-USE-MSG-NEXT:      UNDEFVAR: 11
 UNDEF-USE-MSG-NEXT: {{^}}^{{$}}
 
+; Numeric expression in negative directive using undefined variables.
+RUN: %ProtectFileCheckOutput \
+RUN: not FileCheck --check-prefix UNDEF-USE2 --input-file %s %s 2>&1 \
+RUN:   | FileCheck --strict-whitespace --check-prefix UNDEF-USE-MSG2 %s
+
+CHECK NOT UNDEF VAR USE
+END MARKER
+UNDEF-USE2-LABEL: CHECK NOT UNDEF VAR USE
+UNDEF-USE2-NOT: UNDEFVAR: [[#UNDEFVAR1+UNDEFVAR2]]
+UNDEF-USE2: END MARKER
+UNDEF-USE-MSG2:      numeric-expression.txt:[[#@LINE-4]]:1: error: uses undefined variable(s): "UNDEFVAR1" "UNDEFVAR2"
+UNDEF-USE-MSG2-NEXT:      END MARKER
+UNDEF-USE-MSG2-NEXT: {{^}}^{{$}}
+
 ; Numeric expression with unsupported operator.
 RUN: %ProtectFileCheckOutput \
 RUN: not FileCheck -D#NUMVAR=10 --check-prefix INVAL-OP \
diff --git a/llvm/test/FileCheck/var-scope.txt b/llvm/test/FileCheck/var-scope.txt
--- a/llvm/test/FileCheck/var-scope.txt
+++ b/llvm/test/FileCheck/var-scope.txt
@@ -7,11 +7,11 @@
 
 RUN: FileCheck --check-prefixes CHECK,GLOBAL --enable-var-scope --input-file %s %s
 RUN: %ProtectFileCheckOutput not FileCheck --check-prefixes CHECK,LOCAL1 --enable-var-scope --input-file %s %s 2>&1 \
-RUN:   | FileCheck --check-prefixes ERRUNDEF,ERRUNDEFLOCAL %s
+RUN:   | FileCheck --check-prefix ERRUNDEFLOCAL %s
 RUN: %ProtectFileCheckOutput not FileCheck --check-prefixes CHECK,LOCAL2 --enable-var-scope --input-file %s %s 2>&1 \
-RUN:   | FileCheck --check-prefixes ERRUNDEF,ERRUNDEFLOCNUM %s
+RUN:   | FileCheck --check-prefix ERRUNDEFLOCNUM %s
 RUN: %ProtectFileCheckOutput not FileCheck --check-prefixes CHECK,LOCAL3 --enable-var-scope --input-file %s %s 2>&1 \
-RUN:   | FileCheck --check-prefixes ERRUNDEF,ERRUNDEFLOCAL,ERRUNDEFLOCNUM %s
+RUN:   | FileCheck --check-prefixes ERRUNDEFLOCAL,ERRUNDEFLOCNUM %s
 
 local1
 global1
@@ -33,6 +33,5 @@
 LOCAL3: [[LOCAL]][[#LOCNUM+2]]
 GLOBAL: [[$GLOBAL]][[#$GLOBNUM+2]]
 
-ERRUNDEF: expected string not found in input
 ERRUNDEFLOCAL: uses undefined variable(s): "LOCAL"
 ERRUNDEFLOCNUM: uses undefined variable(s): "LOCNUM"
diff --git a/llvm/utils/FileCheck/FileCheck.cpp b/llvm/utils/FileCheck/FileCheck.cpp
--- a/llvm/utils/FileCheck/FileCheck.cpp
+++ b/llvm/utils/FileCheck/FileCheck.cpp
@@ -197,6 +197,9 @@
 
 static MarkerStyle GetMarker(FileCheckDiag::MatchType MatchTy) {
   switch (MatchTy) {
+  case FileCheckDiag::MatchError:
+    return MarkerStyle('X', raw_ostream::RED, "error: match error",
+                       /*FiltersAsError=*/true);
   case FileCheckDiag::MatchFoundAndExpected:
     return MarkerStyle('^', raw_ostream::GREEN);
   case FileCheckDiag::MatchFoundButExcluded: