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
@@ -621,8 +621,10 @@
   std::string TmpStr;
   if (!Substitutions.empty()) {
     TmpStr = RegExStr;
-    if (LineNumber)
+    if (LineNumber) {
+      Context->LineVariable->clearValue();
       Context->LineVariable->setValue(*LineNumber);
+    }
 
     size_t InsertOffset = 0;
     // Substitute all string variables and expressions whose values are only
@@ -631,10 +633,8 @@
     for (const auto &Substitution : Substitutions) {
       // Substitute and check for failure (e.g. use of undefined variable).
       Expected<std::string> Value = Substitution->getResult();
-      if (!Value) {
-        Context->LineVariable->clearValue();
+      if (!Value)
         return Value.takeError();
-      }
 
       // Plop it into the regex at the adjusted offset.
       TmpStr.insert(TmpStr.begin() + Substitution->getIndex() + InsertOffset,
@@ -644,7 +644,6 @@
 
     // Match the newly constructed regex.
     RegExToMatch = TmpStr;
-    Context->LineVariable->clearValue();
   }
 
   SmallVector<StringRef, 4> MatchInfo;
diff --git a/llvm/test/FileCheck/line-count.txt b/llvm/test/FileCheck/line-count.txt
--- a/llvm/test/FileCheck/line-count.txt
+++ b/llvm/test/FileCheck/line-count.txt
@@ -55,12 +55,18 @@
 55 BAD11: [[@LINE-1x]]
 56 ERR11: line-count.txt:[[#@LINE-1]]:20: error: unexpected characters at end of expression 'x'
 57
-58 CHECK: [[#@LINE]] CHECK
-59 CHECK: [[# @LINE]] CHECK
-60 CHECK: [[# @LINE ]] CHECK
-61
-62 CHECK: [[#@LINE-1]]
-63 CHECK: [[# @LINE-1]] CHECK
-64 CHECK: [[# @LINE -1]] CHECK
-65 CHECK: [[# @LINE - 1]] CHECK
-66 CHECK: [[# @LINE - 1 ]] CHECK
+; RUN: not FileCheck -check-prefix BAD12 -input-file %s %s 2>&1 \
+; RUN:   | FileCheck -check-prefix ERR12 %s
+60
+61 BAD12: [[#@LINE-1]] NOT HERE
+62 ERR12: note: with "@LINE-1" equal to "60"
+63
+64 CHECK: [[#@LINE]] CHECK
+65 CHECK: [[# @LINE]] CHECK
+66 CHECK: [[# @LINE ]] CHECK
+67
+68 CHECK: [[#@LINE-1]]
+69 CHECK: [[# @LINE-1]] CHECK
+70 CHECK: [[# @LINE -1]] CHECK
+71 CHECK: [[# @LINE - 1]] CHECK
+72 CHECK: [[# @LINE - 1 ]] CHECK