diff --git a/.circleci/defaults.sh b/.circleci/defaults.sh
index 1b41e395..e628de7b 100755
--- a/.circleci/defaults.sh
+++ b/.circleci/defaults.sh
@@ -47,7 +47,7 @@ LOCAL_FIRESIM_DIR=$LOCAL_CHIPYARD_DIR/sims/firesim/sim
 
 # key value store to get the build groups
 declare -A grouping
-grouping["group-cores"]="chipyard-ariane chipyard-rocket chipyard-hetero chipyard-boom chipyard-sodor"
+grouping["group-cores"]="chipyard-ariane chipyard-rocket chipyard-hetero chipyard-boom chipyard-sodor chipyard-digitaltop"
 grouping["group-peripherals"]="chipyard-dmirocket chipyard-blkdev chipyard-spiflashread chipyard-spiflashwrite chipyard-mmios chipyard-lbwif"
 grouping["group-accels"]="chipyard-nvdla chipyard-sha3 chipyard-hwacha chipyard-gemmini chipyard-streaming-fir chipyard-streaming-passthrough"
 grouping["group-tracegen"]="tracegen tracegen-boom"
@@ -59,6 +59,7 @@ mapping["chipyard-rocket"]=""
 mapping["chipyard-dmirocket"]=" CONFIG=dmiRocketConfig"
 mapping["chipyard-lbwif"]=" CONFIG=LBWIFRocketConfig"
 mapping["chipyard-sha3"]=" CONFIG=Sha3RocketConfig"
+mapping["chipyard-digitaltop"]=" TOP=DigitalTop"
 mapping["chipyard-streaming-fir"]=" CONFIG=StreamingFIRRocketConfig"
 mapping["chipyard-streaming-passthrough"]=" CONFIG=StreamingPassthroughRocketConfig"
 mapping["chipyard-hetero"]=" CONFIG=LargeBoomAndRocketConfig"
diff --git a/docs/Customization/IOBinders.rst b/docs/Customization/IOBinders.rst
index ff180bcd..1ae95512 100644
--- a/docs/Customization/IOBinders.rst
+++ b/docs/Customization/IOBinders.rst
@@ -4,7 +4,7 @@ IOBinders and HarnessBinders
 In Chipyard we use special ``Parameters`` keys, ``IOBinders`` and ``HarnessBinders`` to bridge the gap between digital system IOs and TestHarness collateral.
 
 IOBinders
-=========
+---------
 
 The ``IOBinder`` functions are responsible for instantiating IO cells and IOPorts in the ``ChipTop`` layer.
 
@@ -19,7 +19,7 @@ For example, the ``WithUARTIOCells`` IOBinder will, for any ``System`` that migh
    :end-before: DOC include end: WithUARTIOCells
 
 HarnessBinders
-==============
+--------------
 
 The ``HarnessBinder`` functions determine what modules to bind to the IOs of a ``ChipTop`` in the ``TestHarness``. The ``HarnessBinder`` interface is designed to be reused across various simulation/implementation modes, enabling decoupling of the target design from simulation and testing concerns.
 
diff --git a/generators/chipyard/src/main/scala/ChipTop.scala b/generators/chipyard/src/main/scala/ChipTop.scala
index 1cef2180..e7456d80 100644
--- a/generators/chipyard/src/main/scala/ChipTop.scala
+++ b/generators/chipyard/src/main/scala/ChipTop.scala
@@ -23,12 +23,10 @@ case object BuildSystem extends Field[Parameters => LazyModule]((p: Parameters)
  * drive clock and reset generation
  */
 
-class ChipTop(implicit p: Parameters) extends LazyModule with HasTestHarnessFunctions {
-  // A publicly accessible list of IO cells (useful for a floorplanning tool, for example)
-  val iocells = ArrayBuffer.empty[IOCell]
-
+class ChipTop(implicit p: Parameters) extends LazyModule
+    with HasTestHarnessFunctions with HasIOBinders {
   // The system module specified by BuildSystem
-  val lazySystem = LazyModule(p(BuildSystem)(p)).suggestName("system")
+  lazy val lazySystem = LazyModule(p(BuildSystem)(p)).suggestName("system")
 
   // The implicitClockSinkNode provides the implicit clock and reset for the System
   val implicitClockSinkNode = ClockSinkNode(Seq(ClockSinkParameters(name = Some("implicit_clock"))))
@@ -45,13 +43,6 @@ class ChipTop(implicit p: Parameters) extends LazyModule with HasTestHarnessFunc
     val implicit_clock = implicitClockSinkNode.in.head._1.clock
     val implicit_reset = implicitClockSinkNode.in.head._1.reset
 
-
-    // Note: IOBinders cannot rely on the implicit clock/reset, as this is a LazyRawModuleImp
-    val (_ports, _iocells, _portMap) = ApplyIOBinders(lazySystem, p(IOBinders))
-    // We ignore _ports for now...
-    iocells ++= _iocells
-    portMap ++= _portMap
-
     // Connect the implicit clock/reset, if present
     lazySystem.module match { case l: LazyModuleImp => {
       l.clock := implicit_clock
diff --git a/generators/chipyard/src/main/scala/HarnessBinders.scala b/generators/chipyard/src/main/scala/HarnessBinders.scala
index b5992c7b..02ab3732 100644
--- a/generators/chipyard/src/main/scala/HarnessBinders.scala
+++ b/generators/chipyard/src/main/scala/HarnessBinders.scala
@@ -1,7 +1,7 @@
 package chipyard.harness
 
 import chisel3._
-import chisel3.experimental.{Analog}
+import chisel3.experimental.{Analog, BaseModule}
 
 import freechips.rocketchip.config.{Field, Config, Parameters}
 import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImpLike}
@@ -27,48 +27,54 @@ import icenet.{CanHavePeripheryIceNIC, SimNetwork, NicLoopback, NICKey, NICIOvon
 
 import scala.reflect.{ClassTag}
 
-case object HarnessBinders extends Field[Map[String, (Any, HasHarnessSignalReferences, Seq[Data]) => Seq[Any]]](
-  Map[String, (Any, HasHarnessSignalReferences, Seq[Data]) => Seq[Any]]().withDefaultValue((t: Any, th: HasHarnessSignalReferences, d: Seq[Data]) => Nil)
+case object HarnessBinders extends Field[Map[String, (Any, HasHarnessSignalReferences, Seq[Data]) => Unit]](
+  Map[String, (Any, HasHarnessSignalReferences, Seq[Data]) => Unit]().withDefaultValue((t: Any, th: HasHarnessSignalReferences, d: Seq[Data]) => ())
 )
 
-
 object ApplyHarnessBinders {
-  def apply(th: HasHarnessSignalReferences, sys: LazyModule, map: Map[String, (Any, HasHarnessSignalReferences, Seq[Data]) => Seq[Any]], portMap: Map[String, Seq[Data]]) = {
+  def apply(th: HasHarnessSignalReferences, sys: LazyModule, portMap: Map[String, Seq[Data]])(implicit p: Parameters): Unit = {
     val pm = portMap.withDefaultValue(Nil)
-    map.map { case (s, f) => f(sys, th, pm(s)) ++ f(sys.module, th, pm(s)) }
+    p(HarnessBinders).foreach { case (s, f) =>
+      f(sys, th, pm(s))
+      f(sys.module, th, pm(s))
+    }
   }
 }
 
-class OverrideHarnessBinder[T, S <: Data](fn: => (T, HasHarnessSignalReferences, Seq[S]) => Seq[Any])(implicit tag: ClassTag[T], ptag: ClassTag[S]) extends Config((site, here, up) => {
-  case HarnessBinders => up(HarnessBinders, site) + (tag.runtimeClass.toString ->
+// The ClassTags here are necessary to overcome issues arising from type erasure
+class HarnessBinder[T, S <: HasHarnessSignalReferences, U <: Data](composer: ((T, S, Seq[U]) => Unit) => (T, S, Seq[U]) => Unit)(implicit systemTag: ClassTag[T], harnessTag: ClassTag[S], portTag: ClassTag[U]) extends Config((site, here, up) => {
+  case HarnessBinders => up(HarnessBinders, site) + (systemTag.runtimeClass.toString ->
       ((t: Any, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
-        val pts = ports.collect({case p: S => p})
-        require (pts.length == ports.length, s"Port type mismatch between IOBinder and HarnessBinder: ${ptag}")
-        t match {
-          case system: T => fn(system, th, pts)
-          case _ => Nil
+        val pts = ports.collect({case p: U => p})
+        require (pts.length == ports.length, s"Port type mismatch between IOBinder and HarnessBinder: ${portTag}")
+        val upfn = up(HarnessBinders, site)(systemTag.runtimeClass.toString)
+        th match {
+          case th: S =>
+            t match {
+              case system: T => composer(upfn)(system, th, pts)
+              case _ =>
+            }
+          case _ =>
         }
       })
   )
 })
 
-class ComposeHarnessBinder[T, S <: Data](fn: => (T, HasHarnessSignalReferences, Seq[S]) => Seq[Any])(implicit tag: ClassTag[T], ptag: ClassTag[S]) extends Config((site, here, up) => {
-  case HarnessBinders => up(HarnessBinders, site) + (tag.runtimeClass.toString ->
-      ((t: Any, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
-        val pts = ports.collect({case p: S => p})
-        require (pts.length == ports.length, s"Port type mismatch between IOBinder and HarnessBinder: ${ptag}")
-        t match {
-          case system: T => up(HarnessBinders, site)(tag.runtimeClass.toString)(system, th, pts) ++ fn(system, th, pts)
-          case _ => Nil
-        }
-      })
-  )
-})
+class OverrideHarnessBinder[T, S <: HasHarnessSignalReferences, U <: Data](fn: => (T, S, Seq[U]) => Unit)
+  (implicit tag: ClassTag[T], thtag: ClassTag[S], ptag: ClassTag[U])
+    extends HarnessBinder[T, S, U]((upfn: (T, S, Seq[U]) => Unit) => fn)
+
+class ComposeHarnessBinder[T, S <: HasHarnessSignalReferences, U <: Data](fn: => (T, S, Seq[U]) => Unit)
+  (implicit tag: ClassTag[T], thtag: ClassTag[S], ptag: ClassTag[U])
+    extends HarnessBinder[T, S, U]((upfn: (T, S, Seq[U]) => Unit) => (t, th, p) => {
+      upfn(t, th, p)
+      fn(t, th, p)
+    })
+
 
 class WithGPIOTiedOff extends OverrideHarnessBinder({
   (system: HasPeripheryGPIOModuleImp, th: HasHarnessSignalReferences, ports: Seq[Analog]) => {
     ports.foreach { _ <> AnalogConst(0) }
-    Nil
   }
 })
 
@@ -76,7 +82,6 @@ class WithGPIOTiedOff extends OverrideHarnessBinder({
 class WithUARTAdapter extends OverrideHarnessBinder({
   (system: HasPeripheryUARTModuleImp, th: HasHarnessSignalReferences, ports: Seq[UARTPortIO]) => {
     UARTAdapter.connect(ports)(system.p)
-    Nil
   }
 })
 // DOC include end: WithUARTAdapter
@@ -84,7 +89,6 @@ class WithUARTAdapter extends OverrideHarnessBinder({
 class WithSimSPIFlashModel(rdOnly: Boolean = true) extends OverrideHarnessBinder({
   (system: HasPeripherySPIFlashModuleImp, th: HasHarnessSignalReferences, ports: Seq[SPIChipIO]) => {
     SimSPIFlashModel.connect(ports, th.harnessReset, rdOnly)(system.p)
-    Nil
   }
 })
 
@@ -92,7 +96,6 @@ class WithSimBlockDevice extends OverrideHarnessBinder({
   (system: CanHavePeripheryBlockDevice, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[BlockDeviceIO]]) => {
     implicit val p: Parameters = GetSystemParameters(system)
     ports.map { b => SimBlockDevice.connect(b.clock, th.harnessReset.asBool, Some(b.bits)) }
-    Nil
   }
 })
 
@@ -100,7 +103,6 @@ class WithBlockDeviceModel extends OverrideHarnessBinder({
   (system: CanHavePeripheryBlockDevice, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[BlockDeviceIO]]) => {
     implicit val p: Parameters = GetSystemParameters(system)
     ports.map { b => withClockAndReset(b.clock, th.harnessReset) { BlockDeviceModel.connect(Some(b.bits)) } }
-    Nil
   }
 })
 
@@ -112,15 +114,13 @@ class WithLoopbackNIC extends OverrideHarnessBinder({
         NicLoopback.connect(Some(n.bits), p(NICKey))
       }
     }
-    Nil
   }
 })
 
 class WithSimNetwork extends OverrideHarnessBinder({
-  (system: CanHavePeripheryIceNIC, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[NICIOvonly]]) => {
+  (system: CanHavePeripheryIceNIC, th: BaseModule with HasHarnessSignalReferences, ports: Seq[ClockedIO[NICIOvonly]]) => {
     implicit val p: Parameters = GetSystemParameters(system)
     ports.map { n => SimNetwork.connect(Some(n.bits), n.clock, th.harnessReset.asBool) }
-    Nil
   }
 })
 
@@ -134,7 +134,6 @@ class WithSimAXIMem extends OverrideHarnessBinder({
       }
       mem.io_axi4.head <> port.bits
     }
-    Nil
   }
 })
 
@@ -149,7 +148,6 @@ class WithBlackBoxSimMem extends OverrideHarnessBinder({
       mem.io.clock := port.clock
       mem.io.reset := port.reset
     }
-    Nil
   }
 })
 
@@ -163,42 +161,39 @@ class WithSimAXIMMIO extends OverrideHarnessBinder({
       }
       mmio_mem.io_axi4.head <> port.bits
     }
-    Nil
   }
 })
 
 class WithTieOffInterrupts extends OverrideHarnessBinder({
   (system: HasExtInterruptsModuleImp, th: HasHarnessSignalReferences, ports: Seq[UInt]) => {
     ports.foreach { _ := 0.U }
-    Nil
   }
 })
 
 class WithTieOffL2FBusAXI extends OverrideHarnessBinder({
   (system: CanHaveSlaveAXI4Port, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[AXI4Bundle]]) => {
     ports.foreach({ p => p := DontCare; p.bits.tieoff() })
-    Nil
   }
 })
 
 class WithSimDebug extends OverrideHarnessBinder({
-  (system: HasPeripheryDebugModuleImp, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
+  (system: HasPeripheryDebug, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
+    implicit val p: Parameters = GetSystemParameters(system)
     ports.map {
       case d: ClockedDMIIO =>
         val dtm_success = WireInit(false.B)
         when (dtm_success) { th.success := true.B }
-        val dtm = Module(new SimDTM()(system.p)).connect(th.harnessClock, th.harnessReset.asBool, d, dtm_success)
+        val dtm = Module(new SimDTM).connect(th.harnessClock, th.harnessReset.asBool, d, dtm_success)
       case j: JTAGIO =>
         val dtm_success = WireInit(false.B)
         when (dtm_success) { th.success := true.B }
         val jtag = Module(new SimJTAG(tickDelay=3)).connect(j, th.harnessClock, th.harnessReset.asBool, ~(th.harnessReset.asBool), dtm_success)
     }
-    Nil
   }
 })
 
 class WithTiedOffDebug extends OverrideHarnessBinder({
-  (system: HasPeripheryDebugModuleImp, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
+  (system: HasPeripheryDebug, th: HasHarnessSignalReferences, ports: Seq[Data]) => {
     ports.map {
       case j: JTAGIO =>
         j.TCK := true.B.asClock
@@ -218,7 +213,6 @@ class WithTiedOffDebug extends OverrideHarnessBinder({
         a.psel := false.B
         a.penable := false.B
     }
-    Nil
   }
 })
 
@@ -247,13 +241,11 @@ class WithSimSerial extends OverrideHarnessBinder({
 class WithTraceGenSuccess extends OverrideHarnessBinder({
   (system: TraceGenSystemModuleImp, th: HasHarnessSignalReferences, ports: Seq[Bool]) => {
     ports.map { p => when (p) { th.success := true.B } }
-    Nil
   }
 })
 
 class WithSimDromajoBridge extends ComposeHarnessBinder({
   (system: CanHaveTraceIOModuleImp, th: HasHarnessSignalReferences, ports: Seq[TraceOutputTop]) => {
     ports.map { p => p.traces.map(tileTrace => SimDromajoBridge(tileTrace)(system.p)) }
-    Nil
   }
 })
diff --git a/generators/chipyard/src/main/scala/IOBinders.scala b/generators/chipyard/src/main/scala/IOBinders.scala
index 246d9c3d..ab6ccdf8 100644
--- a/generators/chipyard/src/main/scala/IOBinders.scala
+++ b/generators/chipyard/src/main/scala/IOBinders.scala
@@ -1,17 +1,17 @@
 package chipyard.iobinders
 
 import chisel3._
-import chisel3.util.experimental.{BoringUtils}
 import chisel3.experimental.{Analog, IO, DataMirror}
 
 import freechips.rocketchip.config._
-import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImpLike}
+import freechips.rocketchip.diplomacy._
 import freechips.rocketchip.devices.debug._
 import freechips.rocketchip.jtag.{JTAGIO}
 import freechips.rocketchip.subsystem._
 import freechips.rocketchip.system.{SimAXIMem}
 import freechips.rocketchip.amba.axi4.{AXI4Bundle, AXI4SlaveNode, AXI4MasterNode, AXI4EdgeParameters}
 import freechips.rocketchip.util._
+import freechips.rocketchip.prci.{ClockSinkNode, ClockSinkParameters}
 import freechips.rocketchip.groundtest.{GroundTestSubsystemModuleImp, GroundTestSubsystem}
 
 import sifive.blocks.devices.gpio._
@@ -26,6 +26,12 @@ import icenet.{CanHavePeripheryIceNIC, SimNetwork, NicLoopback, NICKey, NICIOvon
 
 import scala.reflect.{ClassTag}
 
+object IOBinderTypes {
+  type IOBinderTuple = (Seq[Data], Seq[IOCell])
+  type IOBinderFunction = (Boolean, => Any) => ModuleValue[IOBinderTuple]
+}
+import IOBinderTypes._
+
 // System for instantiating binders based
 // on the scala type of the Target (_not_ its IO). This avoids needing to
 // duplicate harnesses (essentially test harnesses) for each target.
@@ -38,21 +44,30 @@ import scala.reflect.{ClassTag}
 
 // You can add your own binder by adding a new (key, fn) pair, typically by using
 // the OverrideIOBinder or ComposeIOBinder macros
-case object IOBinders extends Field[Map[String, (Any) => (Seq[Data], Seq[IOCell])]](
-  Map[String, (Any) => (Seq[Data], Seq[IOCell])]().withDefaultValue((Any) => (Nil, Nil))
+case object IOBinders extends Field[Map[String, Seq[IOBinderFunction]]](
+  Map[String, Seq[IOBinderFunction]]().withDefaultValue(Nil)
 )
-object ApplyIOBinders {
-  def apply(sys: LazyModule, map: Map[String, (Any) => (Seq[Data], Seq[IOCell])]):
-      (Iterable[Data], Iterable[IOCell], Map[String, Seq[Data]]) = {
-    val lzy = map.map({ case (s,f) => s -> f(sys) })
-    val imp = map.map({ case (s,f) => s -> f(sys.module) })
-    val unzipped = (lzy.values ++ imp.values).unzip
 
-    val ports: Iterable[Data] = unzipped._1.flatten
-    val cells: Iterable[IOCell] = unzipped._2.flatten
-    val portMap: Map[String, Seq[Data]] = map.keys.map(k => k -> (lzy(k)._1 ++ imp(k)._1)).toMap
-    (ports, cells, portMap)
-  }
+abstract trait HasIOBinders { this: LazyModule =>
+  val lazySystem: LazyModule
+  private val iobinders = p(IOBinders)
+  // Note: IOBinders cannot rely on the implicit clock/reset, as they may be called from the
+  // context of a LazyRawModuleImp
+  private val lzy = iobinders.map({ case (s,fns) => s -> fns.map(f => f(true, lazySystem)) })
+  private val imp = iobinders.map({ case (s,fns) => s -> fns.map(f => f(false, lazySystem.module)) })
+
+  private lazy val lzyFlattened: Map[String, IOBinderTuple] = lzy.map({
+    case (s,ms) => s -> (ms.map(_._1).flatten, ms.map(_._2).flatten)
+  })
+  private lazy val impFlattened: Map[String, IOBinderTuple] = imp.map({
+    case (s,ms) => s -> (ms.map(_._1).flatten, ms.map(_._2).flatten)
+  })
+
+  // A publicly accessible list of IO cells (useful for a floorplanning tool, for example)
+  lazy val iocells = (lzyFlattened.values ++ impFlattened.values).unzip._2.flatten.toBuffer
+
+  // A mapping between stringified DigitalSystem traits and their corresponding ChipTop ports
+  lazy val portMap = iobinders.keys.map(k => k -> (lzyFlattened(k)._1 ++ impFlattened(k)._1)).toMap
 }
 
 // Note: The parameters instance is accessible only through LazyModule
@@ -70,63 +85,45 @@ object GetSystemParameters {
   }
 }
 
-class IOBinder(f: (View, View, View) => PartialFunction[Any, Any]) extends Config(f)
-
-// This macro overrides previous matches on some Top mixin. This is useful for
-// binders which drive IO, since those typically cannot be composed
-class OverrideIOBinder[T, S <: Data](fn: => (T) => (Seq[S], Seq[IOCell]))(implicit tag: ClassTag[T]) extends IOBinder((site, here, up) => {
-  case IOBinders => up(IOBinders, site) + (tag.runtimeClass.toString ->
-      ((t: Any) => {
-        t match {
-          case system: T =>
-            val (ports, cells) = fn(system)
-            (ports, cells)
-          case _ => (Nil, Nil)
-        }
-      })
-  )
+class IOBinder[T](composer: Seq[IOBinderFunction] => Seq[IOBinderFunction])(implicit tag: ClassTag[T]) extends Config((site, here, up) => {
+  case IOBinders => up(IOBinders, site) + (tag.runtimeClass.toString -> composer(up(IOBinders, site)(tag.runtimeClass.toString)))
 })
 
-// This macro composes with previous matches on some Top mixin. This is useful for
-// annotation-like binders, since those can typically be composed
-class ComposeIOBinder[T, S <: Data](fn: => (T) => (Seq[S], Seq[IOCell]))(implicit tag: ClassTag[T]) extends IOBinder((site, here, up) => {
-  case IOBinders => up(IOBinders, site) + (tag.runtimeClass.toString ->
-      ((t: Any) => {
-        t match {
-          case system: T =>
-            val r = up(IOBinders, site)(tag.runtimeClass.toString)(system)
-            val h = fn(system)
-            val ports = r._1 ++ h._1
-            val cells = r._2 ++ h._2
-            (ports, cells)
-          case _ => (Nil, Nil)
-        }
-      })
-  )
-})
-
-object BoreHelper {
-  def apply[T <: Data](name: String, source: T): T = {
-    val (io, wire) = source match {
-      case c: Clock =>
-        val wire =  Wire(Clock())
-        // Provide a dummy assignment to prevent FIRRTL invalid assignment
-        // errors prior to running the wiring pass
-        wire := false.B.asClock
-        (IO(Output(Clock())), wire)
-      case r: Reset =>
-        val wire =  Wire(Reset())
-        wire := false.B
-        (IO(Output(Reset())), wire)
+class ConcreteIOBinder[T](composes: Boolean, fn: T => IOBinderTuple)(implicit tag: ClassTag[T]) extends IOBinder[T](
+  up => (if (composes) up else Nil) ++ Seq(((_, t) => { InModuleBody {
+    t match {
+      case system: T => fn(system)
+      case _ => (Nil, Nil)
     }
-    io.suggestName(name)
-    wire.suggestName(s"chiptop_${name}")
-    dontTouch(wire)
-    BoringUtils.bore(source, Seq(wire))
-    io := wire
-    io.asInstanceOf[source.type]
-  }
-}
+  }}): IOBinderFunction)
+)
+
+class LazyIOBinder[T](composes: Boolean, fn: T => ModuleValue[IOBinderTuple])(implicit tag: ClassTag[T]) extends IOBinder[T](
+  up => (if (composes) up else Nil) ++ Seq(((isLazy, t) => {
+    val empty = new ModuleValue[IOBinderTuple] {
+      def getWrappedValue: IOBinderTuple = (Nil, Nil)
+    }
+    if (isLazy) {
+      t match {
+        case system: T => fn(system)
+        case _ => empty
+      }
+    } else {
+      empty
+    }
+  }): IOBinderFunction)
+)
+
+// The "Override" binders override any previous IOBinders (lazy or concrete) defined on the same trait.
+// The "Compose" binders do not override previously defined IOBinders on the same trait
+// The default IOBinders evaluate only in the concrete "ModuleImp" phase of elaboration
+// The "Lazy" IOBinders evaluate in the LazyModule phase, but can also generate hardware through InModuleBody
+
+class OverrideIOBinder[T](fn: T => IOBinderTuple)(implicit tag: ClassTag[T]) extends ConcreteIOBinder[T](false, fn)
+class ComposeIOBinder[T](fn: T => IOBinderTuple)(implicit tag: ClassTag[T]) extends ConcreteIOBinder[T](true, fn)
+
+class OverrideLazyIOBinder[T](fn: T => ModuleValue[IOBinderTuple])(implicit tag: ClassTag[T]) extends LazyIOBinder[T](false, fn)
+class ComposeLazyIOBinder[T](fn: T => ModuleValue[IOBinderTuple])(implicit tag: ClassTag[T]) extends LazyIOBinder[T](true, fn)
 
 
 case object IOCellKey extends Field[IOCellTypeParams](GenericIOCellParams())
@@ -203,55 +200,55 @@ class WithExtInterruptIOCells extends OverrideIOBinder({
 })
 
 
-class WithDebugIOCells extends OverrideIOBinder({
-  (system: HasPeripheryDebugModuleImp) => {
-    system.debug.map({ debug =>
-      val p = system.p
-      val tlbus = system.outer.asInstanceOf[BaseSubsystem].locateTLBusWrapper(p(ExportDebug).slaveWhere)
-      val debug_clock = Wire(Clock()).suggestName("debug_clock")
-      val debug_reset = Wire(Reset()).suggestName("debug_reset")
-      debug_clock := false.B.asClock // must provide default assignment to avoid firrtl unassigned error
-      debug_reset := false.B // must provide default assignment to avoid firrtl unassigned error
-      BoringUtils.bore(tlbus.module.clock, Seq(debug_clock))
-      BoringUtils.bore(tlbus.module.reset, Seq(debug_reset))
+class WithDebugIOCells extends OverrideLazyIOBinder({
+  (system: HasPeripheryDebug) => {
+    implicit val p = GetSystemParameters(system)
+    val tlbus = system.asInstanceOf[BaseSubsystem].locateTLBusWrapper(p(ExportDebug).slaveWhere)
+    val clockSinkNode = system.debugOpt.map(_ => ClockSinkNode(Seq(ClockSinkParameters())))
+    clockSinkNode.map(_ := tlbus.fixedClockNode)
+    def clockBundle = clockSinkNode.get.in.head._1
 
-      // We never use the PSDIO, so tie it off on-chip
-      system.psd.psd.foreach { _ <> 0.U.asTypeOf(new PSDTestMode) }
-      system.resetctrl.map { rcio => rcio.hartIsInReset.map { _ := debug_reset.asBool } }
-      system.debug.map { d =>
-        // Tie off extTrigger
-        d.extTrigger.foreach { t =>
-          t.in.req := false.B
-          t.out.ack := t.out.req
+
+    InModuleBody { system.asInstanceOf[BaseSubsystem].module match { case system: HasPeripheryDebugModuleImp => {
+      system.debug.map({ debug =>
+        // We never use the PSDIO, so tie it off on-chip
+        system.psd.psd.foreach { _ <> 0.U.asTypeOf(new PSDTestMode) }
+        system.resetctrl.map { rcio => rcio.hartIsInReset.map { _ := clockBundle.reset.asBool } }
+        system.debug.map { d =>
+          // Tie off extTrigger
+          d.extTrigger.foreach { t =>
+            t.in.req := false.B
+            t.out.ack := t.out.req
+          }
+          // Tie off disableDebug
+          d.disableDebug.foreach { d => d := false.B }
+          // Drive JTAG on-chip IOs
+          d.systemjtag.map { j =>
+            j.reset := clockBundle.reset
+            j.mfr_id := p(JtagDTMKey).idcodeManufId.U(11.W)
+            j.part_number := p(JtagDTMKey).idcodePartNum.U(16.W)
+            j.version := p(JtagDTMKey).idcodeVersion.U(4.W)
+          }
         }
-        // Tie off disableDebug
-        d.disableDebug.foreach { d => d := false.B }
-        // Drive JTAG on-chip IOs
-        d.systemjtag.map { j =>
-          j.reset := debug_reset
-          j.mfr_id := system.p(JtagDTMKey).idcodeManufId.U(11.W)
-          j.part_number := system.p(JtagDTMKey).idcodePartNum.U(16.W)
-          j.version := system.p(JtagDTMKey).idcodeVersion.U(4.W)
+        Debug.connectDebugClockAndReset(Some(debug), clockBundle.clock)
+
+        // Add IOCells for the DMI/JTAG/APB ports
+        val dmiTuple = debug.clockeddmi.map { d =>
+          IOCell.generateIOFromSignal(d, "dmi", p(IOCellKey), abstractResetAsAsync = true)
         }
-      }
-      Debug.connectDebugClockAndReset(Some(debug), debug_clock)(system.p)
 
-      // Add IOCells for the DMI/JTAG/APB ports
-      val dmiTuple = debug.clockeddmi.map { d =>
-        IOCell.generateIOFromSignal(d, "dmi", p(IOCellKey), abstractResetAsAsync = true)
-      }
+        val jtagTuple = debug.systemjtag.map { j =>
+          IOCell.generateIOFromSignal(j.jtag, "jtag", p(IOCellKey), abstractResetAsAsync = true)
+        }
 
-      val jtagTuple = debug.systemjtag.map { j =>
-        IOCell.generateIOFromSignal(j.jtag, "jtag", p(IOCellKey), abstractResetAsAsync = true)
-      }
+        val apbTuple = debug.apb.map { a =>
+          IOCell.generateIOFromSignal(a, "apb", p(IOCellKey), abstractResetAsAsync = true)
+        }
 
-      val apbTuple = debug.apb.map { a =>
-        IOCell.generateIOFromSignal(a, "apb", p(IOCellKey), abstractResetAsAsync = true)
-      }
-
-      val allTuples = (dmiTuple ++ jtagTuple ++ apbTuple).toSeq
-      (allTuples.map(_._1).toSeq, allTuples.flatMap(_._2).toSeq)
-    }).getOrElse((Nil, Nil))
+        val allTuples = (dmiTuple ++ jtagTuple ++ apbTuple).toSeq
+        (allTuples.map(_._1).toSeq, allTuples.flatMap(_._2).toSeq)
+      }).getOrElse((Nil, Nil))
+    }}}
   }
 })
 
@@ -264,43 +261,62 @@ class WithSerialTLIOCells extends OverrideIOBinder({
 })
 
 
-class WithAXI4MemPunchthrough extends OverrideIOBinder({
+class WithAXI4MemPunchthrough extends OverrideLazyIOBinder({
   (system: CanHaveMasterAXI4MemPort) => {
-    val ports: Seq[ClockedAndResetIO[AXI4Bundle]] = system.mem_axi4.zipWithIndex.map({ case (m, i) =>
-      val p = IO(new ClockedAndResetIO(DataMirror.internal.chiselTypeClone[AXI4Bundle](m))).suggestName(s"axi4_mem_${i}")
-      p.bits <> m
-      val mbus = system.asInstanceOf[HasTileLinkLocations].locateTLBusWrapper(MBUS)
-      p.clock := BoreHelper("axi4_mem_clock",  mbus.module.clock)
-      p.reset := BoreHelper("axi4_mem_reset", mbus.module.reset)
-      p
-    })
-    (ports, Nil)
+    implicit val p: Parameters = GetSystemParameters(system)
+    val clockSinkNode = p(ExtMem).map(_ => ClockSinkNode(Seq(ClockSinkParameters())))
+    clockSinkNode.map(_ := system.asInstanceOf[HasTileLinkLocations].locateTLBusWrapper(MBUS).fixedClockNode)
+    def clockBundle = clockSinkNode.get.in.head._1
+
+    InModuleBody {
+      val ports: Seq[ClockedAndResetIO[AXI4Bundle]] = system.mem_axi4.zipWithIndex.map({ case (m, i) =>
+        val p = IO(new ClockedAndResetIO(DataMirror.internal.chiselTypeClone[AXI4Bundle](m))).suggestName(s"axi4_mem_${i}")
+        p.bits <> m
+        p.clock := clockBundle.clock
+        p.reset := clockBundle.reset
+        p
+      })
+      (ports, Nil)
+    }
   }
 })
 
-class WithAXI4MMIOPunchthrough extends OverrideIOBinder({
+class WithAXI4MMIOPunchthrough extends OverrideLazyIOBinder({
   (system: CanHaveMasterAXI4MMIOPort) => {
-    val ports: Seq[ClockedAndResetIO[AXI4Bundle]] = system.mmio_axi4.zipWithIndex.map({ case (m, i) =>
-      val p = IO(new ClockedAndResetIO(DataMirror.internal.chiselTypeClone[AXI4Bundle](m))).suggestName(s"axi4_mmio_${i}")
-      p.bits <> m
-      val mbus = system.asInstanceOf[HasTileLinkLocations].locateTLBusWrapper(MBUS)
-      p.clock := BoreHelper("axi4_mmio_clock",  mbus.module.clock)
-      p.reset := BoreHelper("axi4_mmio_reset", mbus.module.reset)
-      p
-    })
-    (ports, Nil)
+    implicit val p: Parameters = GetSystemParameters(system)
+    val clockSinkNode = p(ExtBus).map(_ => ClockSinkNode(Seq(ClockSinkParameters())))
+    clockSinkNode.map(_ := system.asInstanceOf[HasTileLinkLocations].locateTLBusWrapper(MBUS).fixedClockNode)
+    def clockBundle = clockSinkNode.get.in.head._1
+
+    InModuleBody {
+      val ports: Seq[ClockedAndResetIO[AXI4Bundle]] = system.mmio_axi4.zipWithIndex.map({ case (m, i) =>
+        val p = IO(new ClockedAndResetIO(DataMirror.internal.chiselTypeClone[AXI4Bundle](m))).suggestName(s"axi4_mmio_${i}")
+        p.bits <> m
+        p.clock := clockBundle.clock
+        p.reset := clockBundle.reset
+        p
+      })
+      (ports, Nil)
+    }
   }
 })
 
-class WithL2FBusAXI4Punchthrough extends OverrideIOBinder({
-   (system: CanHaveSlaveAXI4Port) => {
-    val ports: Seq[ClockedIO[AXI4Bundle]] = system.l2_frontend_bus_axi4.zipWithIndex.map({ case (m, i) =>
-      val p = IO(new ClockedIO(Flipped(DataMirror.internal.chiselTypeClone[AXI4Bundle](m)))).suggestName(s"axi4_fbus_${i}")
-      m <> p.bits
-      p.clock := BoreHelper("axi4_fbus_clock", system.asInstanceOf[BaseSubsystem].fbus.module.clock)
-      p
-    })
-    (ports, Nil)
+class WithL2FBusAXI4Punchthrough extends OverrideLazyIOBinder({
+  (system: CanHaveSlaveAXI4Port) => {
+    implicit val p: Parameters = GetSystemParameters(system)
+    val clockSinkNode = p(ExtIn).map(_ => ClockSinkNode(Seq(ClockSinkParameters())))
+    clockSinkNode.map(_ := system.asInstanceOf[BaseSubsystem].fbus.fixedClockNode)
+    def clockBundle = clockSinkNode.get.in.head._1
+
+    InModuleBody {
+      val ports: Seq[ClockedIO[AXI4Bundle]] = system.l2_frontend_bus_axi4.zipWithIndex.map({ case (m, i) =>
+        val p = IO(new ClockedIO(Flipped(DataMirror.internal.chiselTypeClone[AXI4Bundle](m)))).suggestName(s"axi4_fbus_${i}")
+        m <> p.bits
+        p.clock := clockBundle.clock
+        p
+      })
+      (ports, Nil)
+    }
   }
 })
 
diff --git a/generators/chipyard/src/main/scala/TestHarness.scala b/generators/chipyard/src/main/scala/TestHarness.scala
index 0b49d03c..c638c081 100644
--- a/generators/chipyard/src/main/scala/TestHarness.scala
+++ b/generators/chipyard/src/main/scala/TestHarness.scala
@@ -6,6 +6,7 @@ import freechips.rocketchip.diplomacy.{LazyModule}
 import freechips.rocketchip.config.{Field, Parameters}
 
 import chipyard.harness.{ApplyHarnessBinders, HarnessBinders}
+import chipyard.iobinders.HasIOBinders
 
 // -------------------------------
 // Chipyard Test Harness
@@ -14,9 +15,7 @@ import chipyard.harness.{ApplyHarnessBinders, HarnessBinders}
 case object BuildTop extends Field[Parameters => LazyModule]((p: Parameters) => new ChipTop()(p))
 
 trait HasTestHarnessFunctions {
-  val lazySystem: LazyModule
   val harnessFunctions = ArrayBuffer.empty[HasHarnessSignalReferences => Seq[Any]]
-  val portMap = scala.collection.mutable.Map[String, Seq[Data]]()
 }
 
 trait HasHarnessSignalReferences {
@@ -43,7 +42,9 @@ class TestHarness(implicit val p: Parameters) extends Module with HasHarnessSign
 
   lazyDut match { case d: HasTestHarnessFunctions =>
     d.harnessFunctions.foreach(_(this))
-    ApplyHarnessBinders(this, d.lazySystem, p(HarnessBinders), d.portMap.toMap)
+  }
+  lazyDut match { case d: HasIOBinders =>
+    ApplyHarnessBinders(this, d.lazySystem, d.portMap)
   }
 }
 
diff --git a/generators/chipyard/src/main/scala/config/SodorConfigs.scala b/generators/chipyard/src/main/scala/config/SodorConfigs.scala
index ea245fbc..998ccff9 100644
--- a/generators/chipyard/src/main/scala/config/SodorConfigs.scala
+++ b/generators/chipyard/src/main/scala/config/SodorConfigs.scala
@@ -9,7 +9,7 @@ class Sodor1StageConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.Stage1Factory) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
 
@@ -18,7 +18,7 @@ class Sodor2StageConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.Stage2Factory) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
 
@@ -27,7 +27,7 @@ class Sodor3StageConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.Stage3Factory(ports = 2)) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
 
@@ -36,7 +36,7 @@ class Sodor3StageSinglePortConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.Stage3Factory(ports = 1)) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
 
@@ -45,7 +45,7 @@ class Sodor5StageConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.Stage5Factory) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
 
@@ -54,6 +54,6 @@ class SodorUCodeConfig extends Config(
   new sodor.common.WithNSodorCores(1, internalTile = sodor.common.UCodeFactory) ++
   new testchipip.WithSerialPBusMem ++
   new freechips.rocketchip.subsystem.WithScratchpadsOnly ++    // use sodor tile-internal scratchpad
-  new freechips.rocketchip.subsystem.WithNMemoryChannels(0) ++ // use no external memory
+  new freechips.rocketchip.subsystem.WithNoMemPort ++          // use no external memory
   new freechips.rocketchip.subsystem.WithNBanks(0) ++
   new chipyard.config.AbstractConfig)
diff --git a/generators/firechip/src/main/scala/BridgeBinders.scala b/generators/firechip/src/main/scala/BridgeBinders.scala
index 110afda8..e4f691e2 100644
--- a/generators/firechip/src/main/scala/BridgeBinders.scala
+++ b/generators/firechip/src/main/scala/BridgeBinders.scala
@@ -66,7 +66,7 @@ class WithFireSimIOCellModels extends Config((site, here, up) => {
 })
 
 class WithSerialBridge extends OverrideHarnessBinder({
-  (system: CanHavePeripheryTLSerial, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[SerialIO]]) => {
+  (system: CanHavePeripheryTLSerial, th: FireSim, ports: Seq[ClockedIO[SerialIO]]) => {
     ports.map { port =>
       implicit val p = GetSystemParameters(system)
       val ram = SerialAdapter.connectHarnessRAM(system.serdesser.get, port, th.harnessReset)
@@ -77,7 +77,7 @@ class WithSerialBridge extends OverrideHarnessBinder({
 })
 
 class WithNICBridge extends OverrideHarnessBinder({
-  (system: CanHavePeripheryIceNIC, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[NICIOvonly]]) => {
+  (system: CanHavePeripheryIceNIC, th: FireSim, ports: Seq[ClockedIO[NICIOvonly]]) => {
     val p: Parameters = GetSystemParameters(system)
     ports.map { n => NICBridge(n.clock, n.bits)(p) }
     Nil
@@ -85,12 +85,12 @@ class WithNICBridge extends OverrideHarnessBinder({
 })
 
 class WithUARTBridge extends OverrideHarnessBinder({
-  (system: HasPeripheryUARTModuleImp, th: HasHarnessSignalReferences, ports: Seq[UARTPortIO]) =>
+  (system: HasPeripheryUARTModuleImp, th: FireSim, ports: Seq[UARTPortIO]) =>
     ports.map { p => UARTBridge(th.harnessClock, p)(system.p) }; Nil
 })
 
 class WithBlockDeviceBridge extends OverrideHarnessBinder({
-  (system: CanHavePeripheryBlockDevice, th: HasHarnessSignalReferences, ports: Seq[ClockedIO[BlockDeviceIO]]) => {
+  (system: CanHavePeripheryBlockDevice, th: FireSim, ports: Seq[ClockedIO[BlockDeviceIO]]) => {
     implicit val p: Parameters = GetSystemParameters(system)
     ports.map { b => BlockDevBridge(b.clock, b.bits, th.harnessReset.toBool) }
     Nil
@@ -98,7 +98,7 @@ class WithBlockDeviceBridge extends OverrideHarnessBinder({
 })
 
 class WithFASEDBridge extends OverrideHarnessBinder({
-  (system: CanHaveMasterAXI4MemPort, th: HasHarnessSignalReferences, ports: Seq[ClockedAndResetIO[AXI4Bundle]]) => {
+  (system: CanHaveMasterAXI4MemPort, th: FireSim, ports: Seq[ClockedAndResetIO[AXI4Bundle]]) => {
     implicit val p: Parameters = GetSystemParameters(system)
     (ports zip system.memAXI4Node.edges.in).map { case (axi4, edge) =>
       val nastiKey = NastiParameters(axi4.bits.r.bits.data.getWidth,
@@ -118,20 +118,20 @@ class WithFASEDBridge extends OverrideHarnessBinder({
 })
 
 class WithTracerVBridge extends ComposeHarnessBinder({
-  (system: CanHaveTraceIOModuleImp, th: HasHarnessSignalReferences, ports: Seq[TraceOutputTop]) => {
+  (system: CanHaveTraceIOModuleImp, th: FireSim, ports: Seq[TraceOutputTop]) => {
     ports.map { p => p.traces.map(tileTrace => TracerVBridge(tileTrace)(system.p)) }
     Nil
   }
 })
 
 class WithDromajoBridge extends ComposeHarnessBinder({
-  (system: CanHaveTraceIOModuleImp, th: HasHarnessSignalReferences, ports: Seq[TraceOutputTop]) =>
+  (system: CanHaveTraceIOModuleImp, th: FireSim, ports: Seq[TraceOutputTop]) =>
     ports.map { p => p.traces.map(tileTrace => DromajoBridge(tileTrace)(system.p)) }; Nil
 })
 
 
 class WithTraceGenBridge extends OverrideHarnessBinder({
-  (system: TraceGenSystemModuleImp, th: HasHarnessSignalReferences, ports: Seq[Bool]) =>
+  (system: TraceGenSystemModuleImp, th: FireSim, ports: Seq[Bool]) =>
     ports.map { p => GroundTestBridge(th.harnessClock, p)(system.p) }; Nil
 })
 
diff --git a/generators/firechip/src/main/scala/FireSim.scala b/generators/firechip/src/main/scala/FireSim.scala
index 15defa66..acbdbc6b 100644
--- a/generators/firechip/src/main/scala/FireSim.scala
+++ b/generators/firechip/src/main/scala/FireSim.scala
@@ -153,7 +153,9 @@ class FireSim(implicit val p: Parameters) extends RawModule with HasHarnessSigna
     lazyModule match { case d: HasTestHarnessFunctions =>
       require(d.harnessFunctions.size == 1, "There should only be 1 harness function to connect clock+reset")
       d.harnessFunctions.foreach(_(this))
-      ApplyHarnessBinders(this, d.lazySystem, p(HarnessBinders), d.portMap.toMap)
+    }
+    lazyModule match { case d: HasIOBinders =>
+      ApplyHarnessBinders(this, d.lazySystem, d.portMap)
     }
     NodeIdx.increment()
   }