diff --git a/llvm/docs/CommandGuide/FileCheck.rst b/llvm/docs/CommandGuide/FileCheck.rst
--- a/llvm/docs/CommandGuide/FileCheck.rst
+++ b/llvm/docs/CommandGuide/FileCheck.rst
@@ -598,7 +598,8 @@
 would match ``mov r5, 0xF0F0`` and set ``REG`` to the value ``5`` and ``IMM``
 to the value ``61680``.
 
-The syntax of a numeric substitution is ``[[#%<fmtspec>:<expr>]]`` where:
+The syntax of a numeric substitution is
+``[[#%<fmtspec>: <constraint> <expr>]]`` where:
 
 * ``%<fmtspec>`` is the same matching format specifier as for defining numeric
   variables but acting as a printf-style format to indicate how a numeric
@@ -608,6 +609,12 @@
   if no numeric variable is used.  In case of conflict between matching formats
   of several numeric variables the format specifier is mandatory.
 
+* ``<constraint>`` is the matching constraint describing how the value to match
+  must relate to the value of the numeric expression. The only currently
+  accepted constraint is ``==`` for an exact match and is the default if
+  ``<constraint>`` is not provided. No matching constraint must be specified
+  when the ``<expr>`` is empty.
+
 * ``<expr>>`` is a numeric expression whose operands are either numeric
   variables previously defined or integer immediates.  Currently supported
   numeric operations are ``+`` and ``-``. A single numeric variable or
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
@@ -578,10 +578,23 @@
     Expr = Expr.substr(DefEnd + 1);
   }
 
+  // Parse matching constraint.
+  Expr = Expr.ltrim(SpaceChars);
+  StringRef ConstraintExpr = Expr;
+  if (stripFront(Expr, "==", true /*Optional*/))
+    return true;
+
   // Parse the numeric expression itself.
   Expr = Expr.ltrim(SpaceChars);
   StringRef UseExpr = Expr;
-  if (!Expr.empty()) {
+  if (Expr.empty()) {
+    if (Expr.size() != ConstraintExpr.size()) {
+      SM.PrintMessage(
+          SMLoc::getFromPointer(Expr.data()), SourceMgr::DK_Error,
+          "Empty numeric expression should not have a matching constraint");
+      return true;
+    }
+  } else {
     // First operand in legacy numeric expression is the @LINE pseudo variable.
     enum AllowedOperand AO = Legacy ? LegacyVar : Any;
     NumExprAST = parseNumericOperand(Expr, AO, LineNumber, Context, SM);
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
@@ -183,6 +183,17 @@
 CHECK-LABEL: USE IMPL FMT IMPL MATCH UNSIGNED IMM
 CHECK-NEXT: [[#VAR1+0x8000000000000000]]
 
+; Numeric expressions in default matching format and explicit matching rule using
+; variables defined on other lines
+USE DEF FMT EXPL MATCH
+11
+11
+11
+; CHECK-LABEL: USE DEF FMT EXPL MATCH
+; CHECK-NEXT: [[#==VAR1]]
+; CHECK-NEXT: [[# ==VAR1]]
+; CHECK-NEXT: [[# == VAR1]]
+
 ; Numeric expressions with conversion matching format and implicit matching rule
 ; using variables defined on other lines
 USE CONV FMT IMPL MATCH
@@ -317,7 +328,6 @@
 FMT-CONFLICT-MSG-NEXT: {{F}}MT-CONFLICT-NEXT: {{\[\[#VAR1 \+ VAR2\]\]}}
 FMT-CONFLICT-MSG-NEXT: {{^                      \^$}}
 
-
 ; Numeric expression with overflow
 RUN: not FileCheck -check-prefix OVERFLOW -input-file %s %s 2>&1 \
 RUN:   | FileCheck -check-prefix OVERFLOW-MSG %s
@@ -330,7 +340,6 @@
 OVERFLOW-MSG-NEXT: {{O}}VERFLOW-NEXT: BIGVAR: {{\[\[#BIGVAR:0x8000000000000000\+0x8000000000000000\]\]}}
 OVERFLOW-MSG-NEXT: {{^                          \^$}}
 
-
 ; Numeric expression with underflow
 RUN: not FileCheck -check-prefix UNDERFLOW -input-file %s %s 2>&1 \
 RUN:   | FileCheck -check-prefix UNDERFLOW-MSG %s
@@ -342,3 +351,27 @@
 UNDERFLOW-MSG: numeric-expression.txt:[[#@LINE-1]]:29: error: Unable to substitute variable or numeric expression
 UNDERFLOW-MSG-NEXT: {{U}}NDERFLOW-NEXT: TINYVAR: {{\[\[#%d,TINYVAR:-0x8000000000000000-0x8000000000000000\]\]}}
 UNDERFLOW-MSG-NEXT: {{^                            \^$}}
+
+; Empty numeric expression with matching constraint
+RUN: not FileCheck -check-prefix EMPTY-NUMEXPR-CONSTRAINT -input-file %s %s 2>&1 \
+RUN:   | FileCheck -check-prefix EMPTY-NUMEXPR-CONSTRAINT-MSG %s
+
+EMPTY NUMEXPR USE WITH CONSTRAINT
+18
+EMPTY-NUMEXPR-CONSTRAINT-LABEL: EMPTY NUMEXPR USE WITH CONSTRAINT
+EMPTY-NUMEXPR-CONSTRAINT-NEXT: [[# ==]]
+EMPTY-NUMEXPR-CONSTRAINT-MSG: numeric-expression.txt:[[#@LINE-1]]:38: error: Empty numeric expression should not have a matching constraint
+EMPTY-NUMEXPR-CONSTRAINT-MSG-NEXT: {{E}}MPTY-NUMEXPR-CONSTRAINT-NEXT: {{\[\[# ==\]\]}}
+EMPTY-NUMEXPR-CONSTRAINT-MSG-NEXT: {{^                                     \^$}}
+
+; Empty numeric expression with matching constraint
+RUN: not FileCheck -check-prefix EMPTY-NUMDEF-CONSTRAINT -input-file %s %s 2>&1 \
+RUN:   | FileCheck -check-prefix EMPTY-NUMDEF-CONSTRAINT-MSG %s
+
+EMPTY NUMEXPR DEF WITH CONSTRAINT
+18
+EMPTY-NUMDEF-CONSTRAINT-LABEL: EMPTY NUMEXPR CONSTRAINT
+EMPTY-NUMDEF-CONSTRAINT-NEXT: [[#VARDEF: ==]]
+EMPTY-NUMDEF-CONSTRAINT-MSG: numeric-expression.txt:[[#@LINE-1]]:44: error: Empty numeric expression should not have a matching constraint
+EMPTY-NUMDEF-CONSTRAINT-MSG-NEXT: {{E}}MPTY-NUMDEF-CONSTRAINT-NEXT: {{\[\[#VARDEF: ==\]\]}}
+EMPTY-NUMDEF-CONSTRAINT-MSG-NEXT: {{^                                           \^$}}