diff --git a/mlir/docs/DefiningDialects/Operations.md b/mlir/docs/DefiningDialects/Operations.md
--- a/mlir/docs/DefiningDialects/Operations.md
+++ b/mlir/docs/DefiningDialects/Operations.md
@@ -165,9 +165,10 @@
 Placing the documentation at the beginning is recommended since it helps in
 understanding the operation.
 
-> *   Place documentation at the beginning of the operation definition
-> *   The summary should be short and concise. It should be a one-liner without
->     trailing punctuation. Put expanded explanation in description.
+> *   Place documentation at the beginning of the operation definition.
+> *   The summary should be short and concise. It should be a one-liner
+>     starting with a capital letter and without trailing punctuation.
+>     Put expanded explanation in the description.
 
 ### Operation arguments
 
diff --git a/mlir/tools/mlir-tblgen/DocGenUtilities.h b/mlir/tools/mlir-tblgen/DocGenUtilities.h
--- a/mlir/tools/mlir-tblgen/DocGenUtilities.h
+++ b/mlir/tools/mlir-tblgen/DocGenUtilities.h
@@ -23,6 +23,10 @@
 namespace mlir {
 namespace tblgen {
 
+// Emit the summary. To avoid confusion, the summary is styled differently from
+// the description.
+void emitSummary(llvm::StringRef summary, llvm::raw_ostream &os);
+
 // Emit the description by aligning the text to the left per line (e.g.
 // removing the minimum indentation across the block).
 //
diff --git a/mlir/tools/mlir-tblgen/OpDocGen.cpp b/mlir/tools/mlir-tblgen/OpDocGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDocGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDocGen.cpp
@@ -37,6 +37,14 @@
 
 using mlir::tblgen::Operator;
 
+void mlir::tblgen::emitSummary(StringRef summary, raw_ostream &os) {
+  if (!summary.empty()) {
+    char first = std::toupper(summary.front());
+    llvm::StringRef rest = summary.drop_front();
+    os << "\n_" << first << rest << "_\n\n";
+  }
+}
+
 // Emit the description by aligning the text to the left per line (e.g.,
 // removing the minimum indentation across the block).
 //
@@ -160,7 +168,7 @@
 
   // Emit the summary, syntax, and description if present.
   if (op.hasSummary())
-    os << "\n**Summary:** _" << op.getSummary() << "_\n\n";
+    emitSummary(op.getSummary(), os);
   if (op.hasAssemblyFormat())
     emitAssemblyFormat(op.getOperationName(), op.getAssemblyFormat().trim(),
                        os);
diff --git a/mlir/tools/mlir-tblgen/PassDocGen.cpp b/mlir/tools/mlir-tblgen/PassDocGen.cpp
--- a/mlir/tools/mlir-tblgen/PassDocGen.cpp
+++ b/mlir/tools/mlir-tblgen/PassDocGen.cpp
@@ -21,8 +21,8 @@
 
 /// Emit the documentation for the given pass.
 static void emitDoc(const Pass &pass, raw_ostream &os) {
-  os << llvm::formatv("### `-{0}`: {1}\n", pass.getArgument(),
-                      pass.getSummary());
+  os << llvm::formatv("### `-{0}`\n", pass.getArgument());
+  emitSummary(pass.getSummary(), os);
   emitDescription(pass.getDescription(), os);
 
   // Handle the options of the pass.