diff --git a/mlir/test/mlir-tblgen/op-format-spec.td b/mlir/test/mlir-tblgen/op-format-spec.td
--- a/mlir/test/mlir-tblgen/op-format-spec.td
+++ b/mlir/test/mlir-tblgen/op-format-spec.td
@@ -19,7 +19,7 @@
 //===----------------------------------------------------------------------===//
 // attr-dict
 
-// CHECK: error: 'attr-dict' directive not found in custom assembly format
+// CHECK: error: 'attr-dict' directive not found
 def DirectiveAttrDictInvalidA : TestFormat_Op<"attrdict_invalid_a", [{
 }]>;
 // CHECK: error: 'attr-dict' directive has already been seen
@@ -300,7 +300,7 @@
 def ZCoverageInvalidA : TestFormat_Op<"variable_invalid_a", [{
   attr-dict
 }]>, Arguments<(ins AnyMemRef:$operand)>, Results<(outs AnyMemRef:$result)>;
-// CHECK: error: operand #0, named 'operand', not found in custom assembly format
+// CHECK: error: operand #0, named 'operand', not found
 // CHECK: note: suggest adding a '$operand' directive to the custom assembly format
 def ZCoverageInvalidB : TestFormat_Op<"variable_invalid_b", [{
   type($result) attr-dict
@@ -320,7 +320,7 @@
 def ZCoverageInvalidE : TestFormat_Op<"variable_invalid_e", [{
   attr-dict
 }]>, Results<(outs Variadic<I64>:$result)>;
-// CHECK: error: successor #0, named 'successor', not found in custom assembly format
+// CHECK: error: successor #0, named 'successor', not found
 // CHECK: note: suggest adding a '$successor' directive to the custom assembly format
 def ZCoverageInvalidF : TestFormat_Op<"variable_invalid_f", [{
 	 attr-dict
diff --git a/mlir/tools/mlir-tblgen/OpFormatGen.cpp b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
--- a/mlir/tools/mlir-tblgen/OpFormatGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpFormatGen.cpp
@@ -1055,7 +1055,7 @@
 /// This class implements a simple lexer for operation assembly format strings.
 class FormatLexer {
 public:
-  FormatLexer(llvm::SourceMgr &mgr);
+  FormatLexer(llvm::SourceMgr &mgr, Operator &op);
 
   /// Lex the next token and return it.
   Token lexToken();
@@ -1080,23 +1080,29 @@
   Token lexVariable(const char *tokStart);
 
   llvm::SourceMgr &srcMgr;
+  Operator &op;
   StringRef curBuffer;
   const char *curPtr;
 };
 } // end anonymous namespace
 
-FormatLexer::FormatLexer(llvm::SourceMgr &mgr) : srcMgr(mgr) {
+FormatLexer::FormatLexer(llvm::SourceMgr &mgr, Operator &op)
+    : srcMgr(mgr), op(op) {
   curBuffer = srcMgr.getMemoryBuffer(mgr.getMainFileID())->getBuffer();
   curPtr = curBuffer.begin();
 }
 
 Token FormatLexer::emitError(llvm::SMLoc loc, const Twine &msg) {
   srcMgr.PrintMessage(loc, llvm::SourceMgr::DK_Error, msg);
+  llvm::SrcMgr.PrintMessage(op.getLoc()[0], llvm::SourceMgr::DK_Note,
+                            "in custom assembly format for this operation");
   return formToken(Token::error, loc.getPointer());
 }
 Token FormatLexer::emitErrorAndNote(llvm::SMLoc loc, const Twine &msg,
                                     const Twine &note) {
   srcMgr.PrintMessage(loc, llvm::SourceMgr::DK_Error, msg);
+  llvm::SrcMgr.PrintMessage(op.getLoc()[0], llvm::SourceMgr::DK_Note,
+                            "in custom assembly format for this operation");
   srcMgr.PrintMessage(loc, llvm::SourceMgr::DK_Note, note);
   return formToken(Token::error, loc.getPointer());
 }
@@ -1233,7 +1239,7 @@
 class FormatParser {
 public:
   FormatParser(llvm::SourceMgr &mgr, OperationFormat &format, Operator &op)
-      : lexer(mgr), curToken(lexer.lexToken()), fmt(format), op(op),
+      : lexer(mgr, op), curToken(lexer.lexToken()), fmt(format), op(op),
         seenOperandTypes(op.getNumOperands()),
         seenResultTypes(op.getNumResults()) {}
 
@@ -1481,8 +1487,7 @@
     if (!hasAllOperands && !seenOperands.count(&operand)) {
       return emitErrorAndNote(loc,
                               "operand #" + Twine(i) + ", named '" +
-                                  operand.name +
-                                  "', not found in custom assembly format",
+                                  operand.name + "', not found",
                               "suggest adding a '$" + operand.name +
                                   "' directive to the custom assembly format");
     }
@@ -1572,8 +1577,7 @@
     if (!seenSuccessors.count(&successor)) {
       return emitErrorAndNote(loc,
                               "successor #" + Twine(i) + ", named '" +
-                                  successor.name +
-                                  "', not found in custom assembly format",
+                                  successor.name + "', not found",
                               "suggest adding a '$" + successor.name +
                                   "' directive to the custom assembly format");
     }