diff --git a/mlir/include/mlir/IR/OpBase.td b/mlir/include/mlir/IR/OpBase.td
--- a/mlir/include/mlir/IR/OpBase.td
+++ b/mlir/include/mlir/IR/OpBase.td
@@ -3135,6 +3135,7 @@
 class APFloatParameter<string desc> :
     AttrOrTypeParameter<"::llvm::APFloat", desc> {
   let comparator = "$_lhs.bitwiseIsEqual($_rhs)";
+  let cppAccessorType = "const ::llvm::APFloat &";
 }
 
 // For standard ArrayRefs, which require allocation.
diff --git a/mlir/lib/IR/BuiltinAttributes.cpp b/mlir/lib/IR/BuiltinAttributes.cpp
--- a/mlir/lib/IR/BuiltinAttributes.cpp
+++ b/mlir/lib/IR/BuiltinAttributes.cpp
@@ -283,7 +283,7 @@
 }
 
 LogicalResult FloatAttr::verify(function_ref<InFlightDiagnostic()> emitError,
-                                Type type, APFloat value) {
+                                Type type, const APFloat &value) {
   // Verify that the type is correct.
   if (!type.isa<FloatType>())
     return emitError() << "expected floating point type";
diff --git a/mlir/test/lib/Dialect/Test/TestAttributes.cpp b/mlir/test/lib/Dialect/Test/TestAttributes.cpp
--- a/mlir/test/lib/Dialect/Test/TestAttributes.cpp
+++ b/mlir/test/lib/Dialect/Test/TestAttributes.cpp
@@ -129,7 +129,7 @@
 
 LogicalResult
 TestAttrWithFormatAttr::verify(function_ref<InFlightDiagnostic()> emitError,
-                               int64_t one, std::string two, IntegerAttr three,
+                               int64_t one, StringRef two, IntegerAttr three,
                                ArrayRef<int> four) {
   if (four.size() != static_cast<unsigned>(one))
     return emitError() << "expected 'one' to equal 'four.size()'";
diff --git a/mlir/test/mlir-tblgen/attrdefs.td b/mlir/test/mlir-tblgen/attrdefs.td
--- a/mlir/test/mlir-tblgen/attrdefs.td
+++ b/mlir/test/mlir-tblgen/attrdefs.td
@@ -61,8 +61,8 @@
   let genVerifyDecl = 1;
 
 // DECL-LABEL: class CompoundAAttr : public ::mlir::Attribute
-// DECL: static CompoundAAttr getChecked(::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError, ::mlir::MLIRContext *context, int widthOfSomething, ::test::SimpleTypeA exampleTdType, ::llvm::APFloat apFloat, ::llvm::ArrayRef<int> dims, ::mlir::Type inner);
-// DECL: static ::mlir::LogicalResult verify(::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError, int widthOfSomething, ::test::SimpleTypeA exampleTdType, ::llvm::APFloat apFloat, ::llvm::ArrayRef<int> dims, ::mlir::Type inner);
+// DECL: static CompoundAAttr getChecked(::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError, ::mlir::MLIRContext *context, int widthOfSomething, ::test::SimpleTypeA exampleTdType, const ::llvm::APFloat &apFloat, ::llvm::ArrayRef<int> dims, ::mlir::Type inner);
+// DECL: static ::mlir::LogicalResult verify(::llvm::function_ref<::mlir::InFlightDiagnostic()> emitError, int widthOfSomething, ::test::SimpleTypeA exampleTdType, const ::llvm::APFloat &apFloat, ::llvm::ArrayRef<int> dims, ::mlir::Type inner);
 // DECL: static constexpr ::llvm::StringLiteral getMnemonic() {
 // DECL:   return {"cmpnd_a"};
 // DECL: }
@@ -71,7 +71,7 @@
 // DECL: void print(::mlir::AsmPrinter &printer) const;
 // DECL: int getWidthOfSomething() const;
 // DECL: ::test::SimpleTypeA getExampleTdType() const;
-// DECL: ::llvm::APFloat getApFloat() const;
+// DECL: const ::llvm::APFloat &getApFloat() const;
 
 // Check that AttributeSelfTypeParameter is handled properly.
 // DEF-LABEL: struct CompoundAAttrStorage
@@ -139,5 +139,5 @@
 // DECL-LABEL: class ParamWithAccessorTypeAttr
 // DECL: StringRef getParam()
 // DEF: ParamWithAccessorTypeAttrStorage
-// DEF: ParamWithAccessorTypeAttrStorage(std::string param)
+// DEF: ParamWithAccessorTypeAttrStorage(StringRef param)
 // DEF: StringRef ParamWithAccessorTypeAttr::getParam()
diff --git a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
--- a/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
+++ b/mlir/tools/mlir-tblgen/AttrOrTypeDefGen.cpp
@@ -315,7 +315,7 @@
   SmallVector<MethodParameter> builderParams;
   builderParams.append(prefix.begin(), prefix.end());
   for (auto &param : params)
-    builderParams.emplace_back(param.getCppType(), param.getName());
+    builderParams.emplace_back(param.getCppAccessorType(), param.getName());
   return builderParams;
 }