Index: mlir/test/IR/properties.mlir
===================================================================
--- mlir/test/IR/properties.mlir
+++ mlir/test/IR/properties.mlir
@@ -18,3 +18,9 @@
 // GENERIC: "test.with_wrapped_properties"()
 // GENERIC-SAME:  <{prop = "content for properties"}> : () -> ()
 test.with_wrapped_properties <{prop = "content for properties"}>
+
+// CHECK: test.using_property_in_custom
+// CHECK-SAME: [1, 4, 20]
+// GENERIC: "test.using_property_in_custom"()
+// GENERIC-SAME: prop = array<i64: 1, 4, 20>
+test.using_property_in_custom [1, 4, 20]
Index: mlir/test/lib/Dialect/Test/TestDialect.cpp
===================================================================
--- mlir/test/lib/Dialect/Test/TestDialect.cpp
+++ mlir/test/lib/Dialect/Test/TestDialect.cpp
@@ -1933,6 +1933,21 @@
   return success();
 }
 
+static bool parseUsingPropertyInCustom(OpAsmParser &parser, int64_t value[3]) {
+  return parser.parseLSquare()
+         || parser.parseInteger(value[0])
+         || parser.parseComma()
+         || parser.parseInteger(value[1])
+         || parser.parseComma()
+         || parser.parseInteger(value[2])
+         || parser.parseRSquare();
+}
+
+static void printUsingPropertyInCustom(OpAsmPrinter &printer, Operation *op,
+                                       ArrayRef<int64_t> value) {
+  printer << '[' << value << ']';
+}
+
 #include "TestOpEnums.cpp.inc"
 #include "TestOpInterfaces.cpp.inc"
 #include "TestTypeInterfaces.cpp.inc"
Index: mlir/test/lib/Dialect/Test/TestOps.td
===================================================================
--- mlir/test/lib/Dialect/Test/TestOps.td
+++ mlir/test/lib/Dialect/Test/TestOps.td
@@ -3344,6 +3344,13 @@
   );
 }
 
+def TestOpUsingPropertyInCustom : TEST_Op<"using_property_in_custom"> {
+  let assemblyFormat = "custom<UsingPropertyInCustom>($prop) attr-dict";
+  let arguments = (ins
+    ArrayProperty<"int64_t", 3>:$prop
+  );
+}
+
 // Op with a properties struct defined out-of-line. The struct has custom
 // printer/parser.
 
Index: mlir/test/mlir-tblgen/op-format-invalid.td
===================================================================
--- mlir/test/mlir-tblgen/op-format-invalid.td
+++ mlir/test/mlir-tblgen/op-format-invalid.td
@@ -478,6 +478,11 @@
   let regions = (region AnyRegion:$region);
 }
 
+// CHECK: error: property 'prop' is already bound
+def VariableInvalidO : TestFormat_Op<[{
+  custom<Test>($prop, $prop) attr-dict
+}]>, Arguments<(ins IntProperty<"int64_t">:$prop)>;
+
 //===----------------------------------------------------------------------===//
 // Coverage Checks
 //===----------------------------------------------------------------------===//
Index: mlir/tools/mlir-tblgen/FormatGen.h
===================================================================
--- mlir/tools/mlir-tblgen/FormatGen.h
+++ mlir/tools/mlir-tblgen/FormatGen.h
@@ -235,7 +235,7 @@
 class VariableElement : public FormatElementBase<FormatElement::Variable> {
 public:
   /// These are the kinds of variables.
-  enum Kind { Attribute, Operand, Region, Result, Successor, Parameter };
+  enum Kind { Attribute, Operand, Region, Result, Successor, Parameter, Property };
 
   /// Get the kind of variable.
   Kind getKind() const { return kind; }
Index: mlir/tools/mlir-tblgen/OpFormatGen.cpp
===================================================================
--- mlir/tools/mlir-tblgen/OpFormatGen.cpp
+++ mlir/tools/mlir-tblgen/OpFormatGen.cpp
@@ -94,6 +94,9 @@
 /// This class represents a variable that refers to a successor.
 using SuccessorVariable =
     OpVariableElement<NamedSuccessor, VariableElement::Successor>;
+
+using PropertyVariable =
+    OpVariableElement<NamedProperty, VariableElement::Property>;
 } // namespace
 
 //===----------------------------------------------------------------------===//
@@ -939,6 +942,9 @@
     ctx.addSubst("_ctxt", "parser.getContext()");
     body << tgfmt(string->getValue(), &ctx);
 
+  } else if (auto *property = dyn_cast<PropertyVariable>(param)) {
+    body << llvm::formatv("result.getOrAddProperties<Properties>().{0}",
+                          property->getVar()->name);
   } else {
     llvm_unreachable("unknown custom directive parameter");
   }
@@ -1862,6 +1868,12 @@
     ctx.addSubst("_ctxt", "getContext()");
     body << tgfmt(string->getValue(), &ctx);
 
+  } else if (auto *property = dyn_cast<PropertyVariable>(element)) {
+    FmtContext ctx;
+    ctx.addSubst("_ctxt", "getContext()");
+    const NamedProperty *namedProperty = property->getVar();
+    ctx.addSubst("_storage", "getProperties()." + namedProperty->name);
+    body << tgfmt(namedProperty->prop.getConvertFromStorageCall(), &ctx);
   } else {
     llvm_unreachable("unknown custom directive parameter");
   }
@@ -2457,6 +2469,7 @@
   llvm::DenseSet<const NamedTypeConstraint *> seenOperands;
   llvm::DenseSet<const NamedRegion *> seenRegions;
   llvm::DenseSet<const NamedSuccessor *> seenSuccessors;
+  llvm::DenseSet<const NamedProperty *> seenProperties;
 };
 } // namespace
 
@@ -2941,6 +2954,18 @@
 
     return create<AttributeVariable>(attr);
   }
+
+  if (const NamedProperty *property = findArg(op.getProperties(), name)) {
+    if (ctx != CustomDirectiveContext)
+      return emitError(
+          loc, "properties currently only supported in `custom` directive");
+
+    if (!seenProperties.insert(property).second)
+      return emitError(loc, "property '" + name + "' is already bound");
+
+    return create<PropertyVariable>(property);
+  }
+
   // Operands
   if (const NamedTypeConstraint *operand = findArg(op.getOperands(), name)) {
     if (ctx == TopLevelContext || ctx == CustomDirectiveContext) {
@@ -3070,7 +3095,7 @@
   for (FormatElement *argument : arguments) {
     if (!isa<StringElement, RefDirective, TypeDirective, AttrDictDirective,
              AttributeVariable, OperandVariable, RegionVariable,
-             SuccessorVariable>(argument)) {
+             SuccessorVariable, PropertyVariable>(argument)) {
       // TODO: FormatElement should have location info attached.
       return emitError(loc, "only variables and types may be used as "
                             "parameters to a custom directive");