diff --git a/amaranth/hdl/__init__.py b/amaranth/hdl/__init__.py
index 6ae76f862..769694946 100644
--- a/amaranth/hdl/__init__.py
+++ b/amaranth/hdl/__init__.py
@@ -4,7 +4,7 @@
 from ._dsl import SyntaxError, SyntaxWarning, Module
 from ._cd import DomainError, ClockDomain
 from ._ir import UnusedElaboratable, Elaboratable, DriverConflict, Fragment, Instance
-from ._mem import Memory, ReadPort, WritePort, DummyPort
+from ._mem import MemoryIdentity, MemoryInstance, Memory, ReadPort, WritePort, DummyPort
 from ._rec import Record
 from ._xfrm import DomainRenamer, ResetInserter, EnableInserter
 
@@ -21,7 +21,7 @@
     # _ir
     "UnusedElaboratable", "Elaboratable", "DriverConflict", "Fragment", "Instance",
     # _mem
-    "Memory", "ReadPort", "WritePort", "DummyPort",
+    "MemoryIdentity", "MemoryInstance", "Memory", "ReadPort", "WritePort", "DummyPort",
     # _rec
     "Record",
     # _xfrm
diff --git a/amaranth/hdl/_ir.py b/amaranth/hdl/_ir.py
index 8575e89fc..968b3724b 100644
--- a/amaranth/hdl/_ir.py
+++ b/amaranth/hdl/_ir.py
@@ -1109,7 +1109,7 @@ def emit_read_port(self, module_idx: int, fragment: '_mem.MemoryInstance',
                 en=en,
                 clk=clk,
                 clk_edge=cd.clk_edge,
-                transparent_for=tuple(write_ports[idx] for idx in port._transparency),
+                transparent_for=tuple(write_ports[idx] for idx in port._transparent_for),
                 src_loc=port._data.src_loc,
             )
         data = self.netlist.add_value_cell(len(port._data), cell)
diff --git a/amaranth/hdl/_mem.py b/amaranth/hdl/_mem.py
index b8bca04eb..20bcd9a4d 100644
--- a/amaranth/hdl/_mem.py
+++ b/amaranth/hdl/_mem.py
@@ -5,6 +5,7 @@
 from ._ast import *
 from ._ir import Elaboratable, Fragment
 from ..utils import ceil_log2
+from .._utils import deprecated
 
 
 __all__ = ["Memory", "ReadPort", "WritePort", "DummyPort"]
@@ -33,18 +34,19 @@ def __init__(self, identity, addr, data):
 
 class MemoryInstance(Fragment):
     class _ReadPort:
-        def __init__(self, *, domain, addr, data, en, transparency):
+        def __init__(self, *, domain, addr, data, en, transparent_for):
             assert isinstance(domain, str)
             self._domain = domain
             self._addr = Value.cast(addr)
             self._data = Value.cast(data)
             self._en = Value.cast(en)
-            self._transparency = tuple(transparency)
+            self._transparent_for = tuple(transparent_for)
             assert len(self._en) == 1
             if domain == "comb":
                 assert isinstance(self._en, Const)
                 assert self._en.width == 1
                 assert self._en.value == 1
+                assert not self._transparent_for
 
     class _WritePort:
         def __init__(self, *, domain, addr, data, en):
@@ -70,22 +72,24 @@ def __init__(self, *, identity, width, depth, init=None, attrs=None, src_loc=Non
         self._identity = identity
         self._width = operator.index(width)
         self._depth = operator.index(depth)
-        self._init = tuple(init) if init is not None else ()
+        mask = (1 << self._width) - 1
+        self._init = tuple(item & mask for item in init) if init is not None else ()
         assert len(self._init) <= self._depth
         self._init += (0,) * (self._depth - len(self._init))
         for x in self._init:
             assert isinstance(x, int)
         self._attrs = attrs or {}
-        self._read_ports = []
-        self._write_ports = []
+        self._read_ports: "list[MemoryInstance._ReadPort]" = []
+        self._write_ports: "list[MemoryInstance._WritePort]" = []
 
-    def read_port(self, *, domain, addr, data, en, transparency):
-        port = self._ReadPort(domain=domain, addr=addr, data=data, en=en, transparency=transparency)
+    def read_port(self, *, domain, addr, data, en, transparent_for):
+        port = self._ReadPort(domain=domain, addr=addr, data=data, en=en, transparent_for=transparent_for)
         assert len(port._data) == self._width
         assert len(port._addr) == ceil_log2(self._depth)
-        for x in port._transparency:
-            assert isinstance(x, int)
-            assert x in range(len(self._write_ports))
+        for idx in port._transparent_for:
+            assert isinstance(idx, int)
+            assert idx in range(len(self._write_ports))
+            assert self._write_ports[idx]._domain == port._domain
         for signal in port._data._rhs_signals():
             self.add_driver(signal, port._domain)
         self._read_ports.append(port)
@@ -124,6 +128,8 @@ class Memory(Elaboratable):
     init : list of int
     attrs : dict
     """
+    # TODO(amaranth-0.6): remove
+    @deprecated("`amaranth.hdl.Memory` is deprecated, use `amaranth.lib.memory.Memory` instead")
     def __init__(self, *, width, depth, init=None, name=None, attrs=None, simulate=True):
         if not isinstance(width, int) or width < 0:
             raise TypeError("Memory width must be a non-negative integer, not {!r}"
@@ -132,8 +138,8 @@ def __init__(self, *, width, depth, init=None, name=None, attrs=None, simulate=T
             raise TypeError("Memory depth must be a non-negative integer, not {!r}"
                             .format(depth))
 
-        self.name    = name or tracer.get_var_name(depth=2, default="$memory")
-        self.src_loc = tracer.get_src_loc()
+        self.name    = name or tracer.get_var_name(depth=3, default="$memory")
+        self.src_loc = tracer.get_src_loc(src_loc_at=1)
 
         self.width = width
         self.depth = depth
@@ -208,12 +214,12 @@ def elaborate(self, platform):
         for port in self._read_ports:
             port._MustUse__used = True
             if port.domain == "comb":
-                f.read_port(domain="comb", addr=port.addr, data=port.data, en=Const(1), transparency=())
+                f.read_port(domain="comb", addr=port.addr, data=port.data, en=Const(1), transparent_for=())
             else:
-                transparency = []
+                transparent_for = []
                 if port.transparent:
-                    transparency = write_ports.get(port.domain, [])
-                f.read_port(domain=port.domain, addr=port.addr, data=port.data, en=port.en, transparency=transparency)
+                    transparent_for = write_ports.get(port.domain, [])
+                f.read_port(domain=port.domain, addr=port.addr, data=port.data, en=port.en, transparent_for=transparent_for)
         return f
 
 
@@ -346,13 +352,15 @@ class DummyPort:
     It does not include any read/write port specific attributes, i.e. none besides ``"domain"``;
     any such attributes may be set manually.
     """
+    # TODO(amaranth-0.6): remove
+    @deprecated("`DummyPort` is deprecated, use `amaranth.lib.memory.ReadPort` or `amaranth.lib.memory.WritePort` instead")
     def __init__(self, *, data_width, addr_width, domain="sync", name=None, granularity=None):
         self.domain = domain
 
         if granularity is None:
             granularity = data_width
         if name is None:
-            name = tracer.get_var_name(depth=2, default="dummy")
+            name = tracer.get_var_name(depth=3, default="dummy")
 
         self.addr = Signal(addr_width,
                            name=f"{name}_addr", src_loc_at=1)
diff --git a/amaranth/hdl/_xfrm.py b/amaranth/hdl/_xfrm.py
index e3050e40d..054ff4757 100644
--- a/amaranth/hdl/_xfrm.py
+++ b/amaranth/hdl/_xfrm.py
@@ -263,7 +263,7 @@ def on_fragment(self, fragment):
                     addr=port._addr,
                     data=port._data,
                     en=port._en,
-                    transparency=port._transparency,
+                    transparent_for=port._transparent_for,
                 )
                 for port in fragment._read_ports
             ]
diff --git a/amaranth/lib/fifo.py b/amaranth/lib/fifo.py
index 48023bb01..e376ea181 100644
--- a/amaranth/lib/fifo.py
+++ b/amaranth/lib/fifo.py
@@ -1,12 +1,11 @@
 """First-in first-out queues."""
 
-import warnings
-
 from .. import *
 from ..asserts import *
 from ..utils import ceil_log2
 from .coding import GrayEncoder, GrayDecoder
 from .cdc import FFSynchronizer, AsyncFFSynchronizer
+from .memory import Memory
 
 
 __all__ = ["FIFOInterface", "SyncFIFO", "SyncFIFOBuffered", "AsyncFIFO", "AsyncFIFOBuffered"]
@@ -130,7 +129,7 @@ def elaborate(self, platform):
         do_read  = self.r_rdy & self.r_en
         do_write = self.w_rdy & self.w_en
 
-        storage = m.submodules.storage = Memory(width=self.width, depth=self.depth)
+        storage = m.submodules.storage = Memory(shape=self.width, depth=self.depth, init=[])
         w_port  = storage.write_port()
         r_port  = storage.read_port(domain="comb")
         produce = Signal(range(self.depth))
@@ -257,9 +256,9 @@ def elaborate(self, platform):
 
         do_inner_read  = inner_r_rdy & (~self.r_rdy | self.r_en)
 
-        storage = m.submodules.storage = Memory(width=self.width, depth=inner_depth)
+        storage = m.submodules.storage = Memory(shape=self.width, depth=inner_depth, init=[])
         w_port  = storage.write_port()
-        r_port  = storage.read_port(domain="sync", transparent=False)
+        r_port  = storage.read_port(domain="sync")
         produce = Signal(range(inner_depth))
         consume = Signal(range(inner_depth))
 
@@ -438,9 +437,9 @@ def elaborate(self, platform):
         m.d[self._w_domain] += self.w_level.eq(produce_w_bin - consume_w_bin)
         m.d.comb += self.r_level.eq(produce_r_bin - consume_r_bin)
 
-        storage = m.submodules.storage = Memory(width=self.width, depth=self.depth)
+        storage = m.submodules.storage = Memory(shape=self.width, depth=self.depth, init=[])
         w_port  = storage.write_port(domain=self._w_domain)
-        r_port  = storage.read_port (domain=self._r_domain, transparent=False)
+        r_port  = storage.read_port (domain=self._r_domain)
         m.d.comb += [
             w_port.addr.eq(produce_w_bin[:-1]),
             w_port.data.eq(self.w_data),
diff --git a/amaranth/lib/memory.py b/amaranth/lib/memory.py
new file mode 100644
index 000000000..a1a69f253
--- /dev/null
+++ b/amaranth/lib/memory.py
@@ -0,0 +1,430 @@
+import operator
+from collections import OrderedDict
+from collections.abc import MutableSequence
+
+from ..hdl import MemoryIdentity, MemoryInstance, Shape, ShapeCastable, Const
+from ..hdl._mem import MemorySimRead
+from ..utils import ceil_log2
+from .data import ArrayLayout
+from . import wiring
+from .. import tracer
+
+
+__all__ = ["WritePort", "ReadPort", "Memory"]
+
+
+class WritePort:
+    """A memory write port.
+
+    Parameters
+    ----------
+    signature : :class:`WritePort.Signature`
+        The signature of the port.
+    memory : :class:`Memory` or ``None``
+        Memory associated with the port.
+    domain : str
+        Clock domain. Defaults to ``"sync"``. Writes have a latency of 1 clock cycle.
+
+    Attributes
+    ----------
+    signature : :class:`WritePort.Signature`
+    memory : :class:`Memory`
+    domain : str
+    """
+
+    class Signature(wiring.Signature):
+        """A signature of a write port.
+
+        Parameters
+        ----------
+        addr_width : int
+            Address width in bits. If the port is associated with a :class:`Memory`,
+            it must be equal to :py:`ceil_log2(memory.depth)`.
+        shape : :ref:`shape-like <lang-shapelike>` object
+            The shape of the port data. If the port is associated with a :class:`Memory`,
+            it must be equal to its element shape.
+        granularity : int or ``None``
+            Port granularity. If ``None``, the entire storage element is written at once.
+            Otherwise, determines the size of access covered by a single bit of ``en``.
+            One of the following must hold:
+
+            - ``granularity is None``, in which case ``en_width == 1``, or
+            - ``shape == unsigned(data_width)`` and ``data_width == 0 or data_width % granularity == 0`` in which case ``en_width == data_width // granularity`` (or 0 if ``data_width == 0``)
+            - ``shape == amaranth.lib.data.ArrayLayout(_, elem_count)`` and ``elem_count == 0 or elem_count % granularity == 0`` in which case ``en_width == elem_count // granularity`` (or 0 if ``elem_count == 0``)
+
+        Members
+        -------
+        addr: :py:`unsigned(data_width)`
+        data: ``shape``
+        en: :py:`unsigned(en_width)`
+        """
+
+        def __init__(self, *, addr_width, shape, granularity=None):
+            if not isinstance(addr_width, int) or addr_width < 0:
+                raise TypeError(f"`addr_width` must be a non-negative int, not {addr_width!r}")
+            self._addr_width = addr_width
+            self._shape = shape
+            self._granularity = granularity
+            if granularity is None:
+                en_width = 1
+            elif not isinstance(granularity, int) or granularity < 0:
+                raise TypeError(f"Granularity must be a non-negative int or None, not {granularity!r}")
+            elif not isinstance(shape, ShapeCastable):
+                actual_shape = Shape.cast(shape)
+                if actual_shape.signed:
+                    raise ValueError("Granularity cannot be specified with signed shape")
+                elif actual_shape.width == 0:
+                    en_width = 0
+                elif granularity == 0:
+                    raise ValueError("Granularity must be positive")
+                elif actual_shape.width % granularity != 0:
+                    raise ValueError("Granularity must divide data width")
+                else:
+                    en_width = actual_shape.width // granularity
+            elif isinstance(shape, ArrayLayout):
+                if shape.length == 0:
+                    en_width = 0
+                elif granularity == 0:
+                    raise ValueError("Granularity must be positive")
+                elif shape.length % granularity != 0:
+                    raise ValueError("Granularity must divide data array length")
+                else:
+                    en_width = shape.length // granularity
+            else:
+                raise TypeError("Granularity can only be specified for plain unsigned `Shape` or `ArrayLayout`")
+            super().__init__({
+                "addr": wiring.In(addr_width),
+                "data": wiring.In(shape),
+                "en": wiring.In(en_width),
+            })
+
+        @property
+        def addr_width(self):
+            return self._addr_width
+
+        @property
+        def shape(self):
+            return self._shape
+
+        @property
+        def granularity(self):
+            return self._granularity
+
+        def __repr__(self):
+            granularity = f", granularity={self.granularity}" if self.granularity is not None else ""
+            return f"WritePort.Signature(addr_width={self.addr_width}, shape={self.shape}{granularity})"
+
+
+    def __init__(self, signature, *, memory, domain):
+        if not isinstance(signature, WritePort.Signature):
+            raise TypeError(f"Expected `WritePort.Signature`, not {signature!r}")
+        if memory is not None:
+            if not isinstance(memory, Memory):
+                raise TypeError(f"Expected `Memory` or `None`, not {memory!r}")
+            if signature.shape != memory.shape or Shape.cast(signature.shape) != Shape.cast(memory.shape):
+                raise ValueError(f"Memory shape {memory.shape!r} doesn't match port shape {signature.shape!r}")
+            if signature.addr_width != ceil_log2(memory.depth):
+                raise ValueError(f"Memory address width {ceil_log2(memory.depth)!r} doesn't match port address width {signature.addr_width!r}")
+        if not isinstance(domain, str):
+            raise TypeError(f"Domain has to be a string, not {domain!r}")
+        if domain == "comb":
+            raise ValueError("Write port domain cannot be \"comb\"")
+        self._signature = signature
+        self._memory = memory
+        self._domain = domain
+        self.__dict__.update(signature.members.create())
+        if memory is not None:
+            memory._w_ports.append(self)
+
+    @property
+    def signature(self):
+        return self._signature
+    
+    @property
+    def memory(self):
+        return self._memory
+    
+    @property
+    def domain(self):
+        return self._domain
+
+
+class ReadPort:
+    """A memory read port.
+
+    Parameters
+    ----------
+    signature : :class:`ReadPort.Signature`
+        The signature of the port.
+    memory : :class:`Memory`
+        Memory associated with the port.
+    domain : str
+        Clock domain. Defaults to ``"sync"``. If set to ``"comb"``, the port is asynchronous.
+        Otherwise, the read data becomes available on the next clock cycle.
+    transparent_for : iterable of :class:`WritePort`
+        The set of write ports that this read port should be transparent with. All ports
+        must belong to the same memory and the same clock domain.
+
+    Attributes
+    ----------
+    signature : :class:`ReadPort.Signature`
+    memory : :class:`Memory`
+    domain : str
+    transparent_for : tuple of :class:`WritePort`
+    """
+
+    class Signature(wiring.Signature):
+        """A signature of a read port.
+
+        Parameters
+        ----------
+        addr_width : int
+            Address width in bits. If the port is associated with a :class:`Memory`,
+            it must be equal to :py:`ceil_log2(memory.depth)`.
+        shape : :ref:`shape-like <lang-shapelike>` object
+            The shape of the port data. If the port is associated with a :class:`Memory`,
+            it must be equal to its element shape.
+
+        Members
+        -------
+        addr: :py:`unsigned(data_width)`
+        data: ``shape``
+        en: :py:`unsigned(1)`
+            The enable signal. If ``domain == "comb"``, this is tied to ``Const(1)``.
+            Otherwise it is a signal with ``init=1``.
+        """
+
+        def __init__(self, *, addr_width, shape):
+            if not isinstance(addr_width, int) or addr_width < 0:
+                raise TypeError(f"`addr_width` must be a non-negative int, not {addr_width!r}")
+            self._addr_width = addr_width
+            self._shape = shape
+            super().__init__({
+                "addr": wiring.In(addr_width),
+                "data": wiring.Out(shape),
+                "en": wiring.In(1, init=1),
+            })
+
+        @property
+        def addr_width(self):
+            return self._addr_width
+
+        @property
+        def shape(self):
+            return self._shape
+
+        def __repr__(self):
+            return f"ReadPort.Signature(addr_width={self.addr_width}, shape={self.shape})"
+
+
+    def __init__(self, signature, *, memory, domain, transparent_for=()):
+        if not isinstance(signature, ReadPort.Signature):
+            raise TypeError(f"Expected `ReadPort.Signature`, not {signature!r}")
+        if memory is not None:
+            if not isinstance(memory, Memory):
+                raise TypeError(f"Expected `Memory` or `None`, not {memory!r}")
+            if signature.shape != memory.shape or Shape.cast(signature.shape) != Shape.cast(memory.shape):
+                raise ValueError(f"Memory shape {memory.shape!r} doesn't match port shape {signature.shape!r}")
+            if signature.addr_width != ceil_log2(memory.depth):
+                raise ValueError(f"Memory address width {ceil_log2(memory.depth)!r} doesn't match port address width {signature.addr_width!r}")
+        if not isinstance(domain, str):
+            raise TypeError(f"Domain has to be a string, not {domain!r}")
+        transparent_for = tuple(transparent_for)
+        for port in transparent_for:
+            if not isinstance(port, WritePort):
+                raise TypeError("`transparent_for` must contain only `WritePort` instances")
+            if memory is not None and port not in memory._w_ports:
+                raise ValueError("Transparent write ports must belong to the same memory")
+            if port.domain != domain:
+                raise ValueError("Transparent write ports must belong to the same domain")
+        self._signature = signature
+        self._memory = memory
+        self._domain = domain
+        self._transparent_for = transparent_for
+        self.__dict__.update(signature.members.create())
+        if domain == "comb":
+            self.en = Const(1)
+        if memory is not None:
+            memory._r_ports.append(self)
+
+    @property
+    def signature(self):
+        return self._signature
+    
+    @property
+    def memory(self):
+        return self._memory
+    
+    @property
+    def domain(self):
+        return self._domain
+    
+    @property
+    def transparent_for(self):
+        return self._transparent_for
+
+
+class Memory(wiring.Component):
+    """A word addressable storage.
+
+    Parameters
+    ----------
+    shape : :ref:`shape-like <lang-shapelike>` object
+        The shape of a single element of the storage.
+    depth : int
+        Word count. This memory contains ``depth`` storage elements.
+    init : iterable of int or of any objects accepted by ``shape.const()``
+        Initial values. At power on, each storage element in this memory is initialized to
+        the corresponding element of ``init``, if any, or to the default value of ``shape`` otherwise.
+        Uninitialized memories are not currently supported.
+    attrs : dict
+        Dictionary of synthesis attributes.
+
+    Attributes
+    ----------
+    shape : :ref:`shape-like <lang-shapelike>`
+    depth : int
+    init : :class:`Memory.Init`
+    attrs : dict
+    r_ports : tuple of :class:`ReadPort`
+    w_ports : tuple of :class:`WritePort`
+    """
+
+    class Init(MutableSequence):
+        """Initial data of a :class:`Memory`.
+
+        This is a container implementing the ``MutableSequence`` protocol, enforcing two constraints:
+
+        - the length is immutable and must equal ``depth``
+        - if ``shape`` is a :class:`ShapeCastable`, each element can be cast to ``shape`` via :py:`shape.const()`
+        - otherwise, each element is an :py:`int`
+        """
+        def __init__(self, items, *, shape, depth):
+            Shape.cast(shape)
+            if not isinstance(depth, int) or depth < 0:
+                raise TypeError("Memory depth must be a non-negative integer, not {!r}"
+                                .format(depth))
+            self._shape = shape
+            self._depth = depth
+            if isinstance(shape, ShapeCastable):
+                self._items = [None] * depth
+                default = Const.cast(shape.const(None)).value
+                self._raw = [default] * depth
+            else:
+                self._raw = self._items = [0] * depth
+            try:
+                for idx, item in enumerate(items):
+                    self[idx] = item
+            except (TypeError, ValueError) as e:
+                raise type(e)("Memory initialization value at address {:x}: {}"
+                                .format(idx, e)) from None
+        
+        def __getitem__(self, index):
+            return self._items[index]
+
+        def __setitem__(self, index, value):
+            if isinstance(index, slice):
+                start, stop, step = index.indices(len(self._items))
+                indices = range(start, stop, step)
+                if len(value) != len(indices):
+                    raise ValueError("Changing length of Memory.init is not allowed")
+                for actual_index, actual_value in zip(indices, value):
+                    self[actual_index] = actual_value
+            else:
+                if isinstance(self._shape, ShapeCastable):
+                    self._raw[index] = Const.cast(self._shape.const(value)).value
+                else:
+                    value = operator.index(value)
+                self._items[index] = value
+
+        def __delitem__(self, index):
+            raise TypeError("Deleting items from Memory.init is not allowed")
+        
+        def insert(self, index, value):
+            raise TypeError("Inserting items into Memory.init is not allowed")
+        
+        def __len__(self):
+            return self._depth
+
+        @property
+        def depth(self):
+            return self._depth
+
+        @property
+        def shape(self):
+            return self._shape
+        
+        def __repr__(self):
+            return f"Memory.Init({self._items!r})"
+
+    def __init__(self, *, depth, shape, init, attrs=None, src_loc_at=0, src_loc=None):
+        # shape and depth validation performed in Memory.Init constructor.
+        self._depth = depth
+        self._shape = shape
+        self._init = Memory.Init(init, shape=shape, depth=depth)
+        self._attrs = {} if attrs is None else dict(attrs)
+        self.src_loc = src_loc or tracer.get_src_loc(src_loc_at=src_loc_at)
+        self._identity = MemoryIdentity()
+        self._r_ports: "list[ReadPort]" = []
+        self._w_ports: "list[WritePort]" = []
+        super().__init__(wiring.Signature({}))
+
+    def read_port(self, *, domain="sync", transparent_for=()):
+        """Adds a new read port and returns it.
+
+        Equivalent to creating a :class:`ReadPort` with a signature of :py:`ReadPort.Signature(addr_width=ceil_log2(self.depth), shape=self.shape)`
+        """
+        signature = ReadPort.Signature(addr_width=ceil_log2(self.depth), shape=self.shape)
+        return ReadPort(signature, memory=self, domain=domain, transparent_for=transparent_for)
+
+    def write_port(self, *, domain="sync", granularity=None):
+        """Adds a new write port and returns it.
+
+        Equivalent to creating a :class:`WritePort` with a signature of :py:`WritePort.Signature(addr_width=ceil_log2(self.depth), shape=self.shape, granularity=granularity)`
+        """
+        signature = WritePort.Signature(addr_width=ceil_log2(self.depth), shape=self.shape, granularity=granularity)
+        return WritePort(signature, memory=self, domain=domain)
+
+    @property
+    def depth(self):
+        return self._depth
+
+    @property
+    def shape(self):
+        return self._shape
+
+    @property
+    def init(self):
+        return self._init
+
+    @property
+    def attrs(self):
+        return self._attrs
+
+    @property
+    def w_ports(self):
+        """Returns a tuple of all write ports defined so far."""
+        return tuple(self._w_ports)
+
+    @property
+    def r_ports(self):
+        """Returns a tuple of all read ports defined so far."""
+        return tuple(self._r_ports)
+
+    def elaborate(self, platform):
+        if hasattr(platform, "get_memory"):
+            return platform.get_memory(self)
+        shape = Shape.cast(self.shape)
+        instance = MemoryInstance(identity=self._identity, width=shape.width, depth=self.depth, init=self.init._raw, attrs=self.attrs, src_loc=self.src_loc)
+        w_ports = {}
+        for port in self._w_ports:
+            idx = instance.write_port(domain=port.domain, addr=port.addr, data=port.data, en=port.en)
+            w_ports[port] = idx
+        for port in self._r_ports:
+            transparent_for = [w_ports[write_port] for write_port in port.transparent_for]
+            instance.read_port(domain=port.domain, data=port.data, addr=port.addr, en=port.en, transparent_for=transparent_for)
+        return instance
+
+    def __getitem__(self, index):
+        """Simulation only."""
+        return MemorySimRead(self._identity, index)
diff --git a/amaranth/sim/_pyrtl.py b/amaranth/sim/_pyrtl.py
index d9d11fca4..19666139e 100644
--- a/amaranth/sim/_pyrtl.py
+++ b/amaranth/sim/_pyrtl.py
@@ -505,7 +505,7 @@ def __call__(self, fragment):
                             addr = emitter.def_var("read_addr", f"({(1 << len(port._addr)) - 1:#x} & {addr})")
                             data = emitter.def_var("read_data", f"slots[{memory_index}].read({addr})")
 
-                            for idx in port._transparency:
+                            for idx in port._transparent_for:
                                 waddr, wdata, wen = write_vals[idx]
                                 emitter.append(f"if {addr} == {waddr}:")
                                 with emitter.indent():
diff --git a/amaranth/sim/pysim.py b/amaranth/sim/pysim.py
index bedd951f2..affc3ebc7 100644
--- a/amaranth/sim/pysim.py
+++ b/amaranth/sim/pysim.py
@@ -85,7 +85,7 @@ def __init__(self, fragment, *, vcd_file, gtkw_file=None, traces=()):
                         trace_names[trace_signal] = {("bench", name)}
                         assigned_names.add(name)
                     self.traces.append(trace_signal)
-            elif isinstance(trace, (MemoryInstance, Memory)):
+            elif hasattr(trace, "_identity") and isinstance(trace._identity, MemoryIdentity):
                 if not trace._identity in memories:
                     raise ValueError(f"{trace!r} is a memory not part of the elaborated design")
                 self.traces.append(trace._identity)
diff --git a/docs/changes.rst b/docs/changes.rst
index d7e122bac..2b1e6da5c 100644
--- a/docs/changes.rst
+++ b/docs/changes.rst
@@ -32,6 +32,7 @@ Apply the following changes to code written against Amaranth 0.4 to migrate it t
 * Update uses of ``reset=`` keyword argument to ``init=``
 * Convert uses of ``Simulator.add_sync_process`` used as testbenches to ``Simulator.add_testbench``
 * Convert other uses of ``Simulator.add_sync_process`` to ``Simulator.add_process``
+* Replace uses of ``amaranth.hdl.Memory`` with ``amaranth.lib.memory.Memory``
 
 
 Implemented RFCs
@@ -41,12 +42,14 @@ Implemented RFCs
 .. _RFC 27: https://amaranth-lang.org/rfcs/0027-simulator-testbenches.html
 .. _RFC 39: https://amaranth-lang.org/rfcs/0039-empty-case.html
 .. _RFC 43: https://amaranth-lang.org/rfcs/0043-rename-reset-to-init.html
+.. _RFC 45: https://amaranth-lang.org/rfcs/0045-lib-memory.html
 .. _RFC 46: https://amaranth-lang.org/rfcs/0046-shape-range-1.html
 
 * `RFC 17`_: Remove ``log2_int``
 * `RFC 27`_: Testbench processes for the simulator
 * `RFC 39`_: Change semantics of no-argument ``m.Case()``
 * `RFC 43`_: Rename ``reset=`` to ``init=``
+* `RFC 45`_: Move ``hdl.Memory`` to ``lib.Memory``
 * `RFC 46`_: Change ``Shape.cast(range(1))`` to ``unsigned(0)``
 
 
@@ -65,6 +68,7 @@ Language changes
 * Changed: the ``reset=`` argument of :class:`Signal`, :meth:`Signal.like`, :class:`amaranth.lib.wiring.Member`, :class:`amaranth.lib.cdc.FFSynchronizer`, and ``m.FSM()`` has been renamed to ``init=``. (`RFC 43`_)
 * Changed: :class:`Shape` has been made immutable and hashable.
 * Deprecated: :func:`amaranth.utils.log2_int`. (`RFC 17`_)
+* Deprecated: :class:`amaranth.hdl.Memory`. (`RFC 45`_)
 * Removed: (deprecated in 0.4) :meth:`Const.normalize`. (`RFC 5`_)
 * Removed: (deprecated in 0.4) :class:`Repl`. (`RFC 10`_)
 * Removed: (deprecated in 0.4) :class:`ast.Sample`, :class:`ast.Past`, :class:`ast.Stable`, :class:`ast.Rose`, :class:`ast.Fell`.
@@ -75,6 +79,7 @@ Standard library changes
 
 .. currentmodule:: amaranth.lib
 
+* Added: :mod:`amaranth.lib.memory`. (`RFC 45`_)
 * Removed: (deprecated in 0.4) :mod:`amaranth.lib.scheduler`. (`RFC 19`_)
 * Removed: (deprecated in 0.4) :class:`amaranth.lib.fifo.FIFOInterface` with ``fwft=False``. (`RFC 20`_)
 * Removed: (deprecated in 0.4) :class:`amaranth.lib.fifo.SyncFIFO` with ``fwft=False``. (`RFC 20`_)
diff --git a/docs/stdlib.rst b/docs/stdlib.rst
index 2badf819b..53e0b17d0 100644
--- a/docs/stdlib.rst
+++ b/docs/stdlib.rst
@@ -4,7 +4,7 @@ Standard library
 The :mod:`amaranth.lib` module, also known as the standard library, provides modules that falls into one of the three categories:
 
 1. Modules that will used by essentially all idiomatic Amaranth code, and are necessary for interoperability. This includes :mod:`amaranth.lib.enum` (enumerations), :mod:`amaranth.lib.data` (data structures), and :mod:`amaranth.lib.wiring` (interfaces and components).
-2. Modules that abstract common functionality whose implementation differs between hardware platforms. This includes :mod:`amaranth.lib.cdc`.
+2. Modules that abstract common functionality whose implementation differs between hardware platforms. This includes :mod:`amaranth.lib.cdc`, :mod:`amaranth.lib.memory`.
 3. Modules that have essentially one correct implementation and are of broad utility in digital designs. This includes :mod:`amaranth.lib.coding`, :mod:`amaranth.lib.fifo`, and :mod:`amaranth.lib.crc`.
 
 As part of the Amaranth backwards compatibility guarantee, any behaviors described in these documents will not change from a version to another without at least one version including a warning about the impending change. Any nontrivial change to these behaviors must also go through the public review as a part of the `Amaranth Request for Comments process <https://amaranth-lang.org/rfcs/>`_.
diff --git a/examples/basic/mem.py b/examples/basic/mem.py
index 14bb66159..2a0f6711c 100644
--- a/examples/basic/mem.py
+++ b/examples/basic/mem.py
@@ -1,4 +1,5 @@
 from amaranth import *
+from amaranth.lib.memory import Memory
 from amaranth.cli import main
 
 
@@ -8,12 +9,13 @@ def __init__(self):
         self.dat_r = Signal(8)
         self.dat_w = Signal(8)
         self.we    = Signal()
-        self.mem   = Memory(width=8, depth=16, init=[0xaa, 0x55])
+        self.mem   = Memory(shape=8, depth=16, init=[0xaa, 0x55])
 
     def elaborate(self, platform):
         m = Module()
-        m.submodules.rdport = rdport = self.mem.read_port()
-        m.submodules.wrport = wrport = self.mem.write_port()
+        m.submodules.mem = self.mem
+        rdport = self.mem.read_port()
+        wrport = self.mem.write_port()
         m.d.comb += [
             rdport.addr.eq(self.adr),
             self.dat_r.eq(rdport.data),
diff --git a/tests/test_hdl_mem.py b/tests/test_hdl_mem.py
index e0ec47658..e4f0f3382 100644
--- a/tests/test_hdl_mem.py
+++ b/tests/test_hdl_mem.py
@@ -2,113 +2,128 @@
 
 from amaranth.hdl._ast import *
 from amaranth.hdl._mem import *
+from amaranth._utils import _ignore_deprecated
 
 from .utils import *
 
 
 class MemoryTestCase(FHDLTestCase):
     def test_name(self):
-        m1 = Memory(width=8, depth=4)
-        self.assertEqual(m1.name, "m1")
-        m2 = [Memory(width=8, depth=4)][0]
-        self.assertEqual(m2.name, "$memory")
-        m3 = Memory(width=8, depth=4, name="foo")
-        self.assertEqual(m3.name, "foo")
+        with _ignore_deprecated():
+            m1 = Memory(width=8, depth=4)
+            self.assertEqual(m1.name, "m1")
+            m2 = [Memory(width=8, depth=4)][0]
+            self.assertEqual(m2.name, "$memory")
+            m3 = Memory(width=8, depth=4, name="foo")
+            self.assertEqual(m3.name, "foo")
 
     def test_geometry(self):
-        m = Memory(width=8, depth=4)
-        self.assertEqual(m.width, 8)
-        self.assertEqual(m.depth, 4)
+        with _ignore_deprecated():
+            m = Memory(width=8, depth=4)
+            self.assertEqual(m.width, 8)
+            self.assertEqual(m.depth, 4)
 
     def test_geometry_wrong(self):
-        with self.assertRaisesRegex(TypeError,
-                r"^Memory width must be a non-negative integer, not -1$"):
-            m = Memory(width=-1, depth=4)
-        with self.assertRaisesRegex(TypeError,
-                r"^Memory depth must be a non-negative integer, not -1$"):
-            m = Memory(width=8, depth=-1)
+        with _ignore_deprecated():
+            with self.assertRaisesRegex(TypeError,
+                    r"^Memory width must be a non-negative integer, not -1$"):
+                m = Memory(width=-1, depth=4)
+            with self.assertRaisesRegex(TypeError,
+                    r"^Memory depth must be a non-negative integer, not -1$"):
+                m = Memory(width=8, depth=-1)
 
     def test_init(self):
-        m = Memory(width=8, depth=4, init=range(4))
-        self.assertEqual(m.init, [0, 1, 2, 3])
+        with _ignore_deprecated():
+            m = Memory(width=8, depth=4, init=range(4))
+            self.assertEqual(m.init, [0, 1, 2, 3])
 
     def test_init_wrong_count(self):
-        with self.assertRaisesRegex(ValueError,
-                r"^Memory initialization value count exceed memory depth \(8 > 4\)$"):
-            m = Memory(width=8, depth=4, init=range(8))
+        with _ignore_deprecated():
+            with self.assertRaisesRegex(ValueError,
+                    r"^Memory initialization value count exceed memory depth \(8 > 4\)$"):
+                m = Memory(width=8, depth=4, init=range(8))
 
     def test_init_wrong_type(self):
-        with self.assertRaisesRegex(TypeError,
-                (r"^Memory initialization value at address 1: "
-                    r"'str' object cannot be interpreted as an integer$")):
-            m = Memory(width=8, depth=4, init=[1, "0"])
+        with _ignore_deprecated():
+            with self.assertRaisesRegex(TypeError,
+                    (r"^Memory initialization value at address 1: "
+                        r"'str' object cannot be interpreted as an integer$")):
+                m = Memory(width=8, depth=4, init=[1, "0"])
 
     def test_attrs(self):
-        m1 = Memory(width=8, depth=4)
-        self.assertEqual(m1.attrs, {})
-        m2 = Memory(width=8, depth=4, attrs={"ram_block": True})
-        self.assertEqual(m2.attrs, {"ram_block": True})
+        with _ignore_deprecated():
+            m1 = Memory(width=8, depth=4)
+            self.assertEqual(m1.attrs, {})
+            m2 = Memory(width=8, depth=4, attrs={"ram_block": True})
+            self.assertEqual(m2.attrs, {"ram_block": True})
 
     def test_read_port_transparent(self):
-        mem    = Memory(width=8, depth=4)
-        rdport = mem.read_port()
-        self.assertEqual(rdport.memory, mem)
-        self.assertEqual(rdport.domain, "sync")
-        self.assertEqual(rdport.transparent, True)
-        self.assertEqual(len(rdport.addr), 2)
-        self.assertEqual(len(rdport.data), 8)
-        self.assertEqual(len(rdport.en), 1)
-        self.assertIsInstance(rdport.en, Signal)
-        self.assertEqual(rdport.en.init, 1)
+        with _ignore_deprecated():
+            mem    = Memory(width=8, depth=4)
+            rdport = mem.read_port()
+            self.assertEqual(rdport.memory, mem)
+            self.assertEqual(rdport.domain, "sync")
+            self.assertEqual(rdport.transparent, True)
+            self.assertEqual(len(rdport.addr), 2)
+            self.assertEqual(len(rdport.data), 8)
+            self.assertEqual(len(rdport.en), 1)
+            self.assertIsInstance(rdport.en, Signal)
+            self.assertEqual(rdport.en.init, 1)
 
     def test_read_port_non_transparent(self):
-        mem    = Memory(width=8, depth=4)
-        rdport = mem.read_port(transparent=False)
-        self.assertEqual(rdport.memory, mem)
-        self.assertEqual(rdport.domain, "sync")
-        self.assertEqual(rdport.transparent, False)
-        self.assertEqual(len(rdport.en), 1)
-        self.assertIsInstance(rdport.en, Signal)
-        self.assertEqual(rdport.en.init, 1)
+        with _ignore_deprecated():
+            mem    = Memory(width=8, depth=4)
+            rdport = mem.read_port(transparent=False)
+            self.assertEqual(rdport.memory, mem)
+            self.assertEqual(rdport.domain, "sync")
+            self.assertEqual(rdport.transparent, False)
+            self.assertEqual(len(rdport.en), 1)
+            self.assertIsInstance(rdport.en, Signal)
+            self.assertEqual(rdport.en.init, 1)
 
     def test_read_port_asynchronous(self):
-        mem    = Memory(width=8, depth=4)
-        rdport = mem.read_port(domain="comb")
-        self.assertEqual(rdport.memory, mem)
-        self.assertEqual(rdport.domain, "comb")
-        self.assertEqual(rdport.transparent, True)
-        self.assertEqual(len(rdport.en), 1)
-        self.assertIsInstance(rdport.en, Const)
-        self.assertEqual(rdport.en.value, 1)
+        with _ignore_deprecated():
+            mem    = Memory(width=8, depth=4)
+            rdport = mem.read_port(domain="comb")
+            self.assertEqual(rdport.memory, mem)
+            self.assertEqual(rdport.domain, "comb")
+            self.assertEqual(rdport.transparent, True)
+            self.assertEqual(len(rdport.en), 1)
+            self.assertIsInstance(rdport.en, Const)
+            self.assertEqual(rdport.en.value, 1)
 
     def test_read_port_wrong(self):
-        mem = Memory(width=8, depth=4)
-        with self.assertRaisesRegex(ValueError,
-                r"^Read port cannot be simultaneously asynchronous and non-transparent$"):
-            mem.read_port(domain="comb", transparent=False)
+        with _ignore_deprecated():
+            mem = Memory(width=8, depth=4)
+            with self.assertRaisesRegex(ValueError,
+                    r"^Read port cannot be simultaneously asynchronous and non-transparent$"):
+                mem.read_port(domain="comb", transparent=False)
 
     def test_write_port(self):
-        mem    = Memory(width=8, depth=4)
-        wrport = mem.write_port()
-        self.assertEqual(wrport.memory, mem)
-        self.assertEqual(wrport.domain, "sync")
-        self.assertEqual(wrport.granularity, 8)
-        self.assertEqual(len(wrport.addr), 2)
-        self.assertEqual(len(wrport.data), 8)
-        self.assertEqual(len(wrport.en), 1)
+        with _ignore_deprecated():
+            mem    = Memory(width=8, depth=4)
+            wrport = mem.write_port()
+            self.assertEqual(wrport.memory, mem)
+            self.assertEqual(wrport.domain, "sync")
+            self.assertEqual(wrport.granularity, 8)
+            self.assertEqual(len(wrport.addr), 2)
+            self.assertEqual(len(wrport.data), 8)
+            self.assertEqual(len(wrport.en), 1)
 
     def test_write_port_granularity(self):
-        mem    = Memory(width=8, depth=4)
-        wrport = mem.write_port(granularity=2)
-        self.assertEqual(wrport.memory, mem)
-        self.assertEqual(wrport.domain, "sync")
-        self.assertEqual(wrport.granularity, 2)
-        self.assertEqual(len(wrport.addr), 2)
-        self.assertEqual(len(wrport.data), 8)
-        self.assertEqual(len(wrport.en), 4)
+        with _ignore_deprecated():
+            mem    = Memory(width=8, depth=4)
+            wrport = mem.write_port(granularity=2)
+            self.assertEqual(wrport.memory, mem)
+            self.assertEqual(wrport.domain, "sync")
+            self.assertEqual(wrport.granularity, 2)
+            self.assertEqual(len(wrport.addr), 2)
+            self.assertEqual(len(wrport.data), 8)
+            self.assertEqual(len(wrport.en), 4)
 
     def test_write_port_granularity_wrong(self):
-        mem = Memory(width=8, depth=4)
+        with _ignore_deprecated():
+            mem = Memory(width=8, depth=4)
         with self.assertRaisesRegex(TypeError,
                 r"^Write port granularity must be a non-negative integer, not -1$"):
             mem.write_port(granularity=-1)
@@ -119,20 +134,32 @@ def test_write_port_granularity_wrong(self):
                 r"^Write port granularity must divide memory width evenly$"):
             mem.write_port(granularity=3)
 
+    def test_deprecated(self):
+        with self.assertWarnsRegex(DeprecationWarning,
+                r"^`amaranth.hdl.Memory` is deprecated.*$"):
+            mem = Memory(width=8, depth=4)
+
 
 class DummyPortTestCase(FHDLTestCase):
     def test_name(self):
-        p1 = DummyPort(data_width=8, addr_width=2)
-        self.assertEqual(p1.addr.name, "p1_addr")
-        p2 = [DummyPort(data_width=8, addr_width=2)][0]
-        self.assertEqual(p2.addr.name, "dummy_addr")
-        p3 = DummyPort(data_width=8, addr_width=2, name="foo")
-        self.assertEqual(p3.addr.name, "foo_addr")
+        with _ignore_deprecated():
+            p1 = DummyPort(data_width=8, addr_width=2)
+            self.assertEqual(p1.addr.name, "p1_addr")
+            p2 = [DummyPort(data_width=8, addr_width=2)][0]
+            self.assertEqual(p2.addr.name, "dummy_addr")
+            p3 = DummyPort(data_width=8, addr_width=2, name="foo")
+            self.assertEqual(p3.addr.name, "foo_addr")
 
     def test_sizes(self):
-        p1 = DummyPort(data_width=8, addr_width=2)
-        self.assertEqual(p1.addr.width, 2)
-        self.assertEqual(p1.data.width, 8)
-        self.assertEqual(p1.en.width, 1)
-        p2 = DummyPort(data_width=8, addr_width=2, granularity=2)
-        self.assertEqual(p2.en.width, 4)
+        with _ignore_deprecated():
+            p1 = DummyPort(data_width=8, addr_width=2)
+            self.assertEqual(p1.addr.width, 2)
+            self.assertEqual(p1.data.width, 8)
+            self.assertEqual(p1.en.width, 1)
+            p2 = DummyPort(data_width=8, addr_width=2, granularity=2)
+            self.assertEqual(p2.en.width, 4)
+
+    def test_deprecated(self):
+        with self.assertWarnsRegex(DeprecationWarning,
+                r"^`DummyPort` is deprecated.*$"):
+            DummyPort(data_width=8, addr_width=2)
diff --git a/tests/test_hdl_xfrm.py b/tests/test_hdl_xfrm.py
index d253f0dff..0fc7fb7bc 100644
--- a/tests/test_hdl_xfrm.py
+++ b/tests/test_hdl_xfrm.py
@@ -128,7 +128,8 @@ def test_rename_cd_subfragment(self):
 
     def test_rename_mem_ports(self):
         m = Module()
-        mem = Memory(depth=4, width=16)
+        with _ignore_deprecated():
+            mem = Memory(depth=4, width=16)
         m.submodules.mem = mem
         mem.read_port(domain="a")
         mem.read_port(domain="b")
@@ -397,7 +398,8 @@ def test_enable_subfragment(self):
         """)
 
     def test_enable_read_port(self):
-        mem = Memory(width=8, depth=4)
+        with _ignore_deprecated():
+            mem = Memory(width=8, depth=4)
         mem.read_port(transparent=False)
         f = EnableInserter(self.c1)(mem).elaborate(platform=None)
         self.assertRepr(f._read_ports[0]._en, """
@@ -405,7 +407,8 @@ def test_enable_read_port(self):
         """)
 
     def test_enable_write_port(self):
-        mem = Memory(width=8, depth=4)
+        with _ignore_deprecated():
+            mem = Memory(width=8, depth=4)
         mem.write_port(granularity=2)
         f = EnableInserter(self.c1)(mem).elaborate(platform=None)
         self.assertRepr(f._write_ports[0]._en, """
diff --git a/tests/test_lib_fifo.py b/tests/test_lib_fifo.py
index 5ea9e48a3..126d71f5a 100644
--- a/tests/test_lib_fifo.py
+++ b/tests/test_lib_fifo.py
@@ -6,6 +6,7 @@
 from amaranth.asserts import *
 from amaranth.sim import *
 from amaranth.lib.fifo import *
+from amaranth.lib.memory import *
 
 from .utils import *
 from amaranth._utils import _ignore_deprecated
@@ -81,9 +82,9 @@ def __init__(self, *, width, depth, r_domain, w_domain):
     def elaborate(self, platform):
         m = Module()
 
-        storage = Memory(width=self.width, depth=self.depth)
-        w_port  = m.submodules.w_port = storage.write_port(domain=self.w_domain)
-        r_port  = m.submodules.r_port = storage.read_port (domain="comb")
+        storage = m.submodules.storage = Memory(shape=self.width, depth=self.depth, init=[])
+        w_port  = storage.write_port(domain=self.w_domain)
+        r_port  = storage.read_port (domain="comb")
 
         produce = Signal(range(self.depth))
         consume = Signal(range(self.depth))
diff --git a/tests/test_lib_memory.py b/tests/test_lib_memory.py
new file mode 100644
index 000000000..917097f3e
--- /dev/null
+++ b/tests/test_lib_memory.py
@@ -0,0 +1,369 @@
+# amaranth: UnusedElaboratable=no
+
+from amaranth.hdl._ast import *
+from amaranth.hdl._mem import MemoryInstance
+from amaranth.lib.memory import *
+from amaranth.lib.data import *
+from amaranth.lib.wiring import In, Out, SignatureMembers
+
+from .utils import *
+
+class MyStruct(Struct):
+    a: unsigned(3)
+    b: signed(2)
+
+
+class WritePortTestCase(FHDLTestCase):
+    def test_signature(self):
+        sig = WritePort.Signature(addr_width=2, shape=signed(4))
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, signed(4))
+        self.assertEqual(sig.granularity, None)
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": In(signed(4)),
+            "en": In(1),
+        }))
+        sig = WritePort.Signature(addr_width=2, shape=8, granularity=2)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, 8)
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": In(8),
+            "en": In(4),
+        }))
+        sig = WritePort.Signature(addr_width=2, shape=ArrayLayout(9, 8), granularity=2)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, ArrayLayout(9, 8))
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": In(ArrayLayout(9, 8)),
+            "en": In(4),
+        }))
+        sig = WritePort.Signature(addr_width=2, shape=0, granularity=0)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, 0)
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": In(0),
+            "en": In(0),
+        }))
+        sig = WritePort.Signature(addr_width=2, shape=ArrayLayout(9, 0), granularity=0)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, ArrayLayout(9, 0))
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": In(ArrayLayout(9, 0)),
+            "en": In(0),
+        }))
+
+    def test_signature_wrong(self):
+        with self.assertRaisesRegex(TypeError,
+                "^`addr_width` must be a non-negative int, not -2$"):
+            WritePort.Signature(addr_width=-2, shape=8)
+        with self.assertRaisesRegex(TypeError,
+                "^Granularity must be a non-negative int or None, not -2$"):
+            WritePort.Signature(addr_width=4, shape=8, granularity=-2)
+        with self.assertRaisesRegex(ValueError,
+                "^Granularity cannot be specified with signed shape$"):
+            WritePort.Signature(addr_width=2, shape=signed(8), granularity=2)
+        with self.assertRaisesRegex(TypeError,
+                "^Granularity can only be specified for plain unsigned `Shape` or `ArrayLayout`$"):
+            WritePort.Signature(addr_width=2, shape=MyStruct, granularity=2)
+        with self.assertRaisesRegex(ValueError,
+                "^Granularity must be positive$"):
+            WritePort.Signature(addr_width=2, shape=8, granularity=0)
+        with self.assertRaisesRegex(ValueError,
+                "^Granularity must be positive$"):
+            WritePort.Signature(addr_width=2, shape=ArrayLayout(8, 8), granularity=0)
+        with self.assertRaisesRegex(ValueError,
+                "^Granularity must divide data width$"):
+            WritePort.Signature(addr_width=2, shape=8, granularity=3)
+        with self.assertRaisesRegex(ValueError,
+                "^Granularity must divide data array length$"):
+            WritePort.Signature(addr_width=2, shape=ArrayLayout(8, 8), granularity=3)
+
+    def test_constructor(self):
+        signature = WritePort.Signature(shape=MyStruct, addr_width=4)
+        port = WritePort(signature, memory=None, domain="sync")
+        self.assertEqual(port.signature, signature)
+        self.assertIsNone(port.memory)
+        self.assertEqual(port.domain, "sync")
+        self.assertIsInstance(port.addr, Signal)
+        self.assertEqual(port.addr.shape(), unsigned(4))
+        self.assertIsInstance(port.data, View)
+        self.assertEqual(port.data.shape(), MyStruct)
+        self.assertIsInstance(port.en, Signal)
+        self.assertEqual(port.en.shape(), unsigned(1))
+
+        signature = WritePort.Signature(shape=8, addr_width=4, granularity=2)
+        port = WritePort(signature, memory=None, domain="sync")
+        self.assertEqual(port.signature, signature)
+        self.assertIsNone(port.memory)
+        self.assertEqual(port.domain, "sync")
+        self.assertIsInstance(port.addr, Signal)
+        self.assertEqual(port.addr.shape(), unsigned(4))
+        self.assertIsInstance(port.data, Signal)
+        self.assertEqual(port.data.shape(), unsigned(8))
+        self.assertIsInstance(port.en, Signal)
+        self.assertEqual(port.en.shape(), unsigned(4))
+
+        m = Memory(depth=16, shape=8, init=[])
+        port = WritePort(signature, memory=m, domain="sync")
+        self.assertIs(port.memory, m)
+        self.assertEqual(m.w_ports, (port,))
+
+    def test_constructor_wrong(self):
+        signature = ReadPort.Signature(shape=8, addr_width=4)
+        with self.assertRaisesRegex(TypeError,
+                r"^Expected `WritePort.Signature`, not ReadPort.Signature\(.*\)$"):
+            WritePort(signature, memory=None, domain="sync")
+        signature = WritePort.Signature(shape=8, addr_width=4, granularity=2)
+        with self.assertRaisesRegex(TypeError,
+                r"^Domain has to be a string, not None$"):
+            WritePort(signature, memory=None, domain=None)
+        with self.assertRaisesRegex(TypeError,
+                r"^Expected `Memory` or `None`, not 'a'$"):
+            WritePort(signature, memory="a", domain="sync")
+        with self.assertRaisesRegex(ValueError,
+                r"^Write port domain cannot be \"comb\"$"):
+            WritePort(signature, memory=None, domain="comb")
+        signature = WritePort.Signature(shape=8, addr_width=4)
+        m = Memory(depth=8, shape=8, init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Memory address width 3 doesn't match port address width 4$"):
+            WritePort(signature, memory=m, domain="sync")
+        m = Memory(depth=16, shape=signed(8), init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Memory shape signed\(8\) doesn't match port shape 8$"):
+            WritePort(signature, memory=m, domain="sync")
+
+
+class ReadPortTestCase(FHDLTestCase):
+    def test_signature(self):
+        sig = ReadPort.Signature(addr_width=2, shape=signed(4))
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, signed(4))
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": Out(signed(4)),
+            "en": In(1, init=1),
+        }))
+        sig = ReadPort.Signature(addr_width=2, shape=8)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, 8)
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": Out(8),
+            "en": In(1, init=1),
+        }))
+        sig = ReadPort.Signature(addr_width=2, shape=MyStruct)
+        self.assertEqual(sig.addr_width, 2)
+        self.assertEqual(sig.shape, MyStruct)
+        self.assertEqual(sig.members, SignatureMembers({
+            "addr": In(2),
+            "data": Out(MyStruct),
+            "en": In(1, init=1),
+        }))
+
+    def test_signature_wrong(self):
+        with self.assertRaisesRegex(TypeError,
+                "^`addr_width` must be a non-negative int, not -2$"):
+            ReadPort.Signature(addr_width=-2, shape=8)
+
+    def test_constructor(self):
+        signature = ReadPort.Signature(shape=MyStruct, addr_width=4)
+        port = ReadPort(signature, memory=None, domain="sync")
+        self.assertEqual(port.signature, signature)
+        self.assertIsNone(port.memory)
+        self.assertEqual(port.domain, "sync")
+        self.assertIsInstance(port.addr, Signal)
+        self.assertEqual(port.addr.shape(), unsigned(4))
+        self.assertIsInstance(port.data, View)
+        self.assertEqual(port.data.shape(), MyStruct)
+        self.assertIsInstance(port.en, Signal)
+        self.assertEqual(port.en.shape(), unsigned(1))
+        self.assertEqual(port.transparent_for, ())
+
+        signature = ReadPort.Signature(shape=8, addr_width=4)
+        port = ReadPort(signature, memory=None, domain="comb")
+        self.assertEqual(port.signature, signature)
+        self.assertIsNone(port.memory)
+        self.assertEqual(port.domain, "comb")
+        self.assertIsInstance(port.addr, Signal)
+        self.assertEqual(port.addr.shape(), unsigned(4))
+        self.assertIsInstance(port.data, Signal)
+        self.assertEqual(port.data.shape(), unsigned(8))
+        self.assertIsInstance(port.en, Const)
+        self.assertEqual(port.en.shape(), unsigned(1))
+        self.assertEqual(port.en.value, 1)
+        self.assertEqual(port.transparent_for, ())
+
+        m = Memory(depth=16, shape=8, init=[])
+        port = ReadPort(signature, memory=m, domain="sync")
+        self.assertIs(port.memory, m)
+        self.assertEqual(m.r_ports, (port,))
+        write_port = m.write_port()
+        port = ReadPort(signature, memory=m, domain="sync", transparent_for=[write_port])
+        self.assertIs(port.memory, m)
+        self.assertEqual(port.transparent_for, (write_port,))
+
+    def test_constructor_wrong(self):
+        signature = WritePort.Signature(shape=8, addr_width=4)
+        with self.assertRaisesRegex(TypeError,
+                r"^Expected `ReadPort.Signature`, not WritePort.Signature\(.*\)$"):
+            ReadPort(signature, memory=None, domain="sync")
+        signature = ReadPort.Signature(shape=8, addr_width=4)
+        with self.assertRaisesRegex(TypeError,
+                r"^Domain has to be a string, not None$"):
+            ReadPort(signature, memory=None, domain=None)
+        with self.assertRaisesRegex(TypeError,
+                r"^Expected `Memory` or `None`, not 'a'$"):
+            ReadPort(signature, memory="a", domain="sync")
+        signature = ReadPort.Signature(shape=8, addr_width=4)
+        m = Memory(depth=8, shape=8, init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Memory address width 3 doesn't match port address width 4$"):
+            ReadPort(signature, memory=m, domain="sync")
+        m = Memory(depth=16, shape=signed(8), init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Memory shape signed\(8\) doesn't match port shape 8$"):
+            ReadPort(signature, memory=m, domain="sync")
+        m = Memory(depth=16, shape=8, init=[])
+        port = m.read_port()
+        with self.assertRaisesRegex(TypeError,
+                r"^`transparent_for` must contain only `WritePort` instances$"):
+            ReadPort(signature, memory=m, domain="sync", transparent_for=[port])
+        write_port = m.write_port()
+        m2 = Memory(depth=16, shape=8, init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Transparent write ports must belong to the same memory$"):
+            ReadPort(signature, memory=m2, domain="sync", transparent_for=[write_port])
+        with self.assertRaisesRegex(ValueError,
+                r"^Transparent write ports must belong to the same domain$"):
+            ReadPort(signature, memory=m, domain="other", transparent_for=[write_port])
+
+
+class MemoryTestCase(FHDLTestCase):
+    def test_constructor(self):
+        m = Memory(shape=8, depth=4, init=[1, 2, 3])
+        self.assertEqual(m.shape, 8)
+        self.assertEqual(m.depth, 4)
+        self.assertEqual(m.init.shape, 8)
+        self.assertEqual(m.init.depth, 4)
+        self.assertEqual(m.attrs, {})
+        self.assertIsInstance(m.init, Memory.Init)
+        self.assertEqual(list(m.init), [1, 2, 3, 0])
+        self.assertEqual(m.init._raw, [1, 2, 3, 0])
+        self.assertRepr(m.init, "Memory.Init([1, 2, 3, 0])")
+        self.assertEqual(m.r_ports, ())
+        self.assertEqual(m.w_ports, ())
+
+    def test_constructor_shapecastable(self):
+        init = [
+            {"a": 0, "b": 1},
+            {"a": 2, "b": 3},
+        ]
+        m = Memory(shape=MyStruct, depth=4, init=init, attrs={"ram_style": "block"})
+        self.assertEqual(m.shape, MyStruct)
+        self.assertEqual(m.depth, 4)
+        self.assertEqual(m.attrs, {"ram_style": "block"})
+        self.assertIsInstance(m.init, Memory.Init)
+        self.assertEqual(list(m.init), [{"a": 0, "b": 1}, {"a": 2, "b": 3}, None, None])
+        self.assertEqual(m.init._raw, [8, 0x1a, 0, 0])
+
+    def test_constructor_wrong(self):
+        with self.assertRaisesRegex(TypeError,
+                r"^Memory depth must be a non-negative integer, not 'a'$"):
+            Memory(shape=8, depth="a", init=[])
+        with self.assertRaisesRegex(TypeError,
+                r"^Memory depth must be a non-negative integer, not -1$"):
+            Memory(shape=8, depth=-1, init=[])
+        with self.assertRaisesRegex(TypeError,
+                r"^Object 'a' cannot be converted to an Amaranth shape$"):
+            Memory(shape="a", depth=3, init=[])
+        with self.assertRaisesRegex(TypeError,
+                (r"^Memory initialization value at address 1: "
+                    r"'str' object cannot be interpreted as an integer$")):
+            Memory(shape=8, depth=4, init=[1, "0"])
+
+    def test_init_set(self):
+        m = Memory(shape=8, depth=4, init=[])
+        m.init[1] = 2
+        self.assertEqual(list(m.init), [0, 2, 0, 0])
+        self.assertEqual(m.init._raw, [0, 2, 0, 0])
+        m.init[2:] = [4, 5]
+        self.assertEqual(list(m.init), [0, 2, 4, 5])
+
+    def test_init_set_shapecastable(self):
+        m = Memory(shape=MyStruct, depth=4, init=[])
+        m.init[1] = {"a": 1, "b": 2}
+        self.assertEqual(list(m.init), [None, {"a": 1, "b": 2}, None, None])
+        self.assertEqual(m.init._raw, [0, 0x11, 0, 0])
+
+    def test_init_set_wrong(self):
+        m = Memory(shape=8, depth=4, init=[])
+        with self.assertRaisesRegex(TypeError,
+                r"^'str' object cannot be interpreted as an integer$"):
+            m.init[0] = "a"
+        m = Memory(shape=MyStruct, depth=4, init=[])
+        # underlying TypeError message differs between PyPy and CPython
+        with self.assertRaises(TypeError):
+            m.init[0] = 1
+
+    def test_init_set_slice_wrong(self):
+        m = Memory(shape=8, depth=4, init=[])
+        with self.assertRaisesRegex(ValueError,
+                r"^Changing length of Memory.init is not allowed$"):
+            m.init[1:] = [1, 2]
+        with self.assertRaisesRegex(TypeError,
+                r"^Deleting items from Memory.init is not allowed$"):
+            del m.init[1:2]
+        with self.assertRaisesRegex(TypeError,
+                r"^Inserting items into Memory.init is not allowed$"):
+            m.init.insert(1, 3)
+
+    def test_port(self):
+        for depth, addr_width in [
+            (0, 0),
+            (1, 0),
+            (3, 2),
+            (4, 2),
+            (5, 3),
+        ]:
+            m = Memory(shape=8, depth=depth, init=[])
+            rp = m.read_port()
+            self.assertEqual(rp.signature.addr_width, addr_width)
+            self.assertEqual(rp.signature.shape, 8)
+            wp = m.write_port()
+            self.assertEqual(wp.signature.addr_width, addr_width)
+            self.assertEqual(wp.signature.shape, 8)
+            self.assertEqual(m.r_ports, (rp,))
+            self.assertEqual(m.w_ports, (wp,))
+
+    def test_elaborate(self):
+        m = Memory(shape=MyStruct, depth=4, init=[{"a": 1, "b": 2}])
+        wp = m.write_port()
+        rp0 = m.read_port(domain="sync", transparent_for=[wp])
+        rp1 = m.read_port(domain="comb")
+        f = m.elaborate(None)
+        self.assertIsInstance(f, MemoryInstance)
+        self.assertIs(f._identity, m._identity)
+        self.assertEqual(f._depth, 4)
+        self.assertEqual(f._width, 5)
+        self.assertEqual(f._init, (0x11, 0, 0, 0))
+        self.assertEqual(f._write_ports[0]._domain, "sync")
+        self.assertEqual(f._write_ports[0]._granularity, 5)
+        self.assertIs(f._write_ports[0]._addr, wp.addr)
+        self.assertIs(f._write_ports[0]._data, wp.data.as_value())
+        self.assertIs(f._write_ports[0]._en, wp.en)
+        self.assertEqual(f._read_ports[0]._domain, "sync")
+        self.assertEqual(f._read_ports[0]._transparent_for, (0,))
+        self.assertIs(f._read_ports[0]._addr, rp0.addr)
+        self.assertIs(f._read_ports[0]._data, rp0.data.as_value())
+        self.assertIs(f._read_ports[0]._en, rp0.en)
+        self.assertEqual(f._read_ports[1]._domain, "comb")
+        self.assertEqual(f._read_ports[1]._transparent_for, ())
+        self.assertIs(f._read_ports[1]._addr, rp1.addr)
+        self.assertIs(f._read_ports[1]._data, rp1.data.as_value())
+        self.assertIs(f._read_ports[1]._en, rp1.en)
diff --git a/tests/test_sim.py b/tests/test_sim.py
index 8cac7f81d..1afe63b50 100644
--- a/tests/test_sim.py
+++ b/tests/test_sim.py
@@ -5,13 +5,13 @@
 from amaranth._utils import flatten
 from amaranth.hdl._ast import *
 from amaranth.hdl._cd import  *
-from amaranth.hdl._mem import *
 with warnings.catch_warnings():
     warnings.filterwarnings(action="ignore", category=DeprecationWarning)
     from amaranth.hdl.rec import *
 from amaranth.hdl._dsl import  *
 from amaranth.hdl._ir import *
 from amaranth.sim import *
+from amaranth.lib.memory import Memory
 
 from .utils import *
 from amaranth._utils import _ignore_deprecated
@@ -752,14 +752,12 @@ def process():
             sim.add_testbench(process)
         self.assertTrue(survived)
 
-    def setUp_memory(self, rd_synchronous=True, rd_transparent=True, wr_granularity=None):
+    def setUp_memory(self, rd_synchronous=True, rd_transparent=False, wr_granularity=None):
         self.m = Module()
-        self.memory = Memory(width=8, depth=4, init=[0xaa, 0x55])
-        self.m.submodules.rdport = self.rdport = \
-            self.memory.read_port(domain="sync" if rd_synchronous else "comb",
-                                  transparent=rd_transparent)
-        self.m.submodules.wrport = self.wrport = \
-            self.memory.write_port(granularity=wr_granularity)
+        self.memory = self.m.submodules.memory = Memory(shape=8, depth=4, init=[0xaa, 0x55])
+        self.wrport = self.memory.write_port(granularity=wr_granularity)
+        self.rdport = self.memory.read_port(domain="sync" if rd_synchronous else "comb",
+                                            transparent_for=[self.wrport] if rd_transparent else [])
 
     def test_memory_init(self):
         self.setUp_memory()
@@ -862,8 +860,8 @@ def process():
 
     def test_memory_read_only(self):
         self.m = Module()
-        self.memory = Memory(width=8, depth=4, init=[0xaa, 0x55])
-        self.m.submodules.rdport = self.rdport = self.memory.read_port()
+        self.m.submodules.memory = self.memory = Memory(shape=8, depth=4, init=[0xaa, 0x55])
+        self.rdport = self.memory.read_port()
         with self.assertSimulation(self.m) as sim:
             def process():
                 yield Tick()
@@ -920,9 +918,9 @@ def process():
     def test_memory_transparency_simple(self):
         m = Module()
         init = [0x11, 0x22, 0x33, 0x44]
-        m.submodules.memory = memory = Memory(width=8, depth=4, init=init)
-        rdport = memory.read_port()
+        m.submodules.memory = memory = Memory(shape=8, depth=4, init=init)
         wrport = memory.write_port(granularity=8)
+        rdport = memory.read_port(transparent_for=[wrport])
         with self.assertSimulation(m) as sim:
             def process():
                 yield rdport.addr.eq(0)
@@ -959,9 +957,9 @@ def process():
     def test_memory_transparency_multibit(self):
         m = Module()
         init = [0x11111111, 0x22222222, 0x33333333, 0x44444444]
-        m.submodules.memory = memory = Memory(width=32, depth=4, init=init)
-        rdport = memory.read_port()
+        m.submodules.memory = memory = Memory(shape=32, depth=4, init=init)
         wrport = memory.write_port(granularity=8)
+        rdport = memory.read_port(transparent_for=[wrport])
         with self.assertSimulation(m) as sim:
             def process():
                 yield rdport.addr.eq(0)