diff --git a/mlir/test/mlir-tblgen/op-default-builder.td b/mlir/test/mlir-tblgen/op-default-builder.td
new file mode 100644
--- /dev/null
+++ b/mlir/test/mlir-tblgen/op-default-builder.td
@@ -0,0 +1,71 @@
+// RUN: mlir-tblgen -gen-op-decls -I %S/../../include %s | FileCheck %s
+
+include "mlir/IR/AttrTypeBase.td"
+include "mlir/IR/EnumAttr.td"
+include "mlir/IR/OpBase.td"
+
+def Test_Dialect : Dialect {
+  let name = "test";
+  let cppNamespace = "foobar";
+}
+class NS_Op<string mnemonic, list<Trait> traits> :
+    Op<Test_Dialect, mnemonic, traits>;
+
+def SomeAttr : Attr<CPred<"some-condition">, "some attribute kind"> {
+  let storageType = "some-attr-kind";
+  let returnType = "some-return-type";
+  let convertFromStorage = "$_self.some-convert-from-storage()";
+  let constBuilderCall = "some-const-builder-call($_builder, $0)";
+}
+
+def AOp : NS_Op<"a_op", []> {
+  let arguments = (ins
+      FloatLike:$lhs,
+      SomeAttr:$aAttr,
+      DefaultValuedAttr<SomeAttr, "4.2">:$bAttr,
+      OptionalAttr<SomeAttr>:$cAttr,
+      DefaultValuedOptionalAttr<SomeAttr, "7.2">:$dAttr
+  );
+}
+
+// CHECK-LABEL: AOp declarations
+// Note: `cAttr` below could be conditionally optional and so the generation is
+// currently conservative.
+// CHECK-DAG: ::mlir::Value lhs, some-attr-kind aAttr, some-attr-kind bAttr, /*optional*/some-attr-kind cAttr, /*optional*/some-attr-kind dAttr);
+// CHECK-DAG: ::mlir::Value lhs, some-return-type aAttr, some-return-type bAttr, /*optional*/some-attr-kind cAttr, /*optional*/some-return-type dAttr = 7.2);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, ::mlir::Value lhs, some-attr-kind aAttr, some-attr-kind bAttr, /*optional*/some-attr-kind cAttr, /*optional*/some-attr-kind dAttr);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, ::mlir::Value lhs, some-return-type aAttr, some-return-type bAttr, /*optional*/some-attr-kind cAttr, /*optional*/some-return-type dAttr = 7.2);
+
+def BOp : NS_Op<"b_op", []> {
+  let arguments = (ins
+      DefaultValuedAttr<SomeAttr, "6.2">:$aAttr,
+      DefaultValuedAttr<SomeAttr, "4.2">:$bAttr
+  );
+}
+
+// Verify that non-overlapping builders created where all could be elided.
+// CHECK-LABEL: BOp declarations
+// CHECK-DAG: some-attr-kind aAttr, some-attr-kind bAttr = nullptr);
+// CHECK-DAG: some-return-type aAttr = 6.2, some-return-type bAttr = 4.2);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, some-attr-kind aAttr, some-attr-kind bAttr = nullptr);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, some-return-type aAttr = 6.2, some-return-type bAttr = 4.2);
+
+def COp : NS_Op<"c_op", []> {
+  let arguments = (ins
+    FloatLike:$value,
+    OptionalAttr<SymbolRefArrayAttr>:$ag,
+    OptionalAttr<SymbolRefArrayAttr>:$as,
+    OptionalAttr<SymbolRefArrayAttr>:$nos,
+    OptionalAttr<I64Attr>:$al,
+    UnitAttr:$vo,
+    UnitAttr:$non
+  );
+}
+
+// CHECK-LABEL: COp declarations
+// Note: `al` below could be conditionally optional and so the generation is
+// currently conservative.
+// CHECK-DAG: ::mlir::Value value, /*optional*/::mlir::ArrayAttr ag, /*optional*/::mlir::ArrayAttr as, /*optional*/::mlir::ArrayAttr nos, /*optional*/::mlir::IntegerAttr al, /*optional*/::mlir::UnitAttr vo, /*optional*/::mlir::UnitAttr non = nullptr);
+// CHECK-DAG: ::mlir::Value value, /*optional*/::mlir::ArrayAttr ag, /*optional*/::mlir::ArrayAttr as, /*optional*/::mlir::ArrayAttr nos, /*optional*/::mlir::IntegerAttr al, /*optional*/bool vo = false, /*optional*/bool non = false);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, ::mlir::Value value, /*optional*/::mlir::ArrayAttr ag, /*optional*/::mlir::ArrayAttr as, /*optional*/::mlir::ArrayAttr nos, /*optional*/::mlir::IntegerAttr al, /*optional*/::mlir::UnitAttr vo, /*optional*/::mlir::UnitAttr non = nullptr);
+// CHECK-DAG: ::mlir::TypeRange resultTypes, ::mlir::Value value, /*optional*/::mlir::ArrayAttr ag, /*optional*/::mlir::ArrayAttr as, /*optional*/::mlir::ArrayAttr nos, /*optional*/::mlir::IntegerAttr al, /*optional*/bool vo = false, /*optional*/bool non = false);
diff --git a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
--- a/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
+++ b/mlir/tools/mlir-tblgen/OpDefinitionsGen.cpp
@@ -2048,15 +2048,18 @@
   // Successors and variadic regions go at the end of the parameter list, so no
   // default arguments are possible.
   bool hasTrailingParams = op.getNumSuccessors() || op.getNumVariadicRegions();
-  if (attrParamKind == AttrParamKind::UnwrappedValue && !hasTrailingParams) {
+  if (!hasTrailingParams) {
     // Calculate the start index from which we can attach default values in the
     // builder declaration.
     for (int i = op.getNumArgs() - 1; i >= 0; --i) {
       auto *namedAttr = op.getArg(i).dyn_cast<tblgen::NamedAttribute *>();
-      if (!namedAttr || !namedAttr->attr.hasDefaultValue())
+      if (!namedAttr)
         break;
-
-      if (!canUseUnwrappedRawValue(namedAttr->attr))
+      Attribute attr = namedAttr->attr;
+      // TODO: Currently we can't differentiate between optional meaning do not
+      // verify/not always error if missing or optional meaning need not be
+      // specified in builder. Expand isOptional once we can differentiate.
+      if (attr.hasDefaultValue() || attr.isDerivedAttr())
         break;
 
       // Creating an APInt requires us to provide bitwidth, value, and
@@ -2071,6 +2074,21 @@
       defaultValuedAttrStartIndex = i;
     }
   }
+  // Avoid generating build methods that are ambiguous due to default values by
+  // requiring at least one attribute.
+  if (defaultValuedAttrStartIndex < op.getNumArgs()) {
+    // TODO: This should have been possible as a cast<NamedAttribute> but
+    // required template instantiations is not yet defined for the tblgen helper
+    // classes.
+    auto* namedAttr =
+        cast<NamedAttribute*>(op.getArg(defaultValuedAttrStartIndex));
+    Attribute attr = namedAttr->attr;
+    if ((attrParamKind == AttrParamKind::WrappedAttr &&
+         canUseUnwrappedRawValue(attr)) ||
+        (attrParamKind == AttrParamKind::UnwrappedValue &&
+         !canUseUnwrappedRawValue(attr)))
+      ++defaultValuedAttrStartIndex;
+  }
 
   /// Collect any inferred attributes.
   for (const NamedTypeConstraint &operand : op.getOperands()) {
@@ -2117,9 +2135,12 @@
 
     // Attach default value if requested and possible.
     std::string defaultValue;
-    if (attrParamKind == AttrParamKind::UnwrappedValue &&
-        i >= defaultValuedAttrStartIndex) {
-      defaultValue += attr.getDefaultValue();
+    if (i >= defaultValuedAttrStartIndex) {
+      if (attrParamKind == AttrParamKind::UnwrappedValue &&
+          canUseUnwrappedRawValue(attr))
+        defaultValue += attr.getDefaultValue();
+      else
+        defaultValue += "nullptr";
     }
     paramList.emplace_back(type, namedAttr.name, StringRef(defaultValue),
                            attr.isOptional());