diff --git a/mlir/include/mlir/IR/Diagnostics.h b/mlir/include/mlir/IR/Diagnostics.h
--- a/mlir/include/mlir/IR/Diagnostics.h
+++ b/mlir/include/mlir/IR/Diagnostics.h
@@ -432,7 +432,7 @@
 
   /// Emit a diagnostic using the registered issue handler if present, or with
   /// the default behavior if not.
-  void emit(Diagnostic diag);
+  void emit(Diagnostic &diag);
 
 private:
   friend class MLIRContextImpl;
diff --git a/mlir/lib/IR/Diagnostics.cpp b/mlir/lib/IR/Diagnostics.cpp
--- a/mlir/lib/IR/Diagnostics.cpp
+++ b/mlir/lib/IR/Diagnostics.cpp
@@ -191,7 +191,7 @@
   // If this diagnostic is still inflight and it hasn't been abandoned, then
   // report it.
   if (isInFlight()) {
-    owner->emit(std::move(*impl));
+    owner->emit(*impl);
     owner = nullptr;
   }
   impl.reset();
@@ -277,7 +277,7 @@
 
 /// Emit a diagnostic using the registered issue handler if present, or with
 /// the default behavior if not.
-void DiagnosticEngine::emit(Diagnostic diag) {
+void DiagnosticEngine::emit(Diagnostic &diag) {
   assert(diag.getSeverity() != DiagnosticSeverity::Note &&
          "notes should not be emitted directly");
   impl->emit(std::move(diag));
@@ -869,13 +869,12 @@
       return;
 
     // Emit the diagnostics back to the context.
-    emitDiagnostics([&](Diagnostic diag) {
-      return context->getDiagEngine().emit(std::move(diag));
-    });
+    emitDiagnostics(
+        [&](Diagnostic &diag) { return context->getDiagEngine().emit(diag); });
   }
 
   /// Utility method to emit any held diagnostics.
-  void emitDiagnostics(llvm::function_ref<void(Diagnostic)> emitFn) const {
+  void emitDiagnostics(llvm::function_ref<void(Diagnostic &)> emitFn) const {
     // Stable sort all of the diagnostics that were emitted. This creates a
     // deterministic ordering for the diagnostics based upon which order id they
     // were emitted for.
@@ -883,7 +882,7 @@
 
     // Emit each diagnostic to the context again.
     for (ThreadDiagnostic &diag : diagnostics)
-      emitFn(std::move(diag.diag));
+      emitFn(diag.diag);
   }
 
   /// Set the order id for the current thread.