diff --git a/cranelift/docs/langref.rst b/cranelift/docs/langref.rst
index 911714751f..4156a95aa3 100644
--- a/cranelift/docs/langref.rst
+++ b/cranelift/docs/langref.rst
@@ -533,49 +533,13 @@ than the native pointer size, for example unsigned :type:`i32` offsets on a
     :arg Name: String identifying the heap in the runtime environment.
     :result H: Heap identifier.
 
-.. inst:: a = heap_load H, p, Offset
-
-    Load a value at the address ``p + Offset`` in the heap H.
-
-    Trap if the heap access would be out of bounds.
-
-    :arg H: Heap identifier created by :inst:`heap`.
-    :arg iN p: Unsigned base address in heap.
-    :arg Offset: Immediate signed offset.
-    :flag align(N): Expected alignment of ``p + Offset``. Power of two.
-    :flag aligntrap: Always trap if the memory access is misaligned.
-    :result T a: Loaded value.
-
-.. inst:: a = heap_store H, x, p, Offset
-
-    Store a value at the address ``p + Offset`` in the heap H.
-
-    Trap if the heap access would be out of bounds.
-
-    :arg H: Heap identifier created by :inst:`heap`.
-    :arg T x: Value to be stored.
-    :arg iN p: Unsigned base address in heap.
-    :arg Offset: Immediate signed offset.
-    :flag align(N): Expected alignment of ``p + Offset``. Power of two.
-    :flag aligntrap: Always trap if the memory access is misaligned.
+.. autoinst:: heap_load
+.. autoinst:: heap_store
 
 When optimizing heap accesses, Cretonne may separate the heap bounds checking
 and address computations from the memory accesses.
 
-.. inst:: a = heap_addr H, p, Size
-
-    Bounds check and compute absolute address of heap memory.
-
-    Verify that the address range ``p .. p + Size - 1`` is valid in the heap H,
-    and trap if not.
-
-    Convert the heap-relative address in ``p`` to a real absolute address and
-    return it.
-
-    :arg H: Heap identifier created by :inst:`heap`.
-    :arg iN p: Unsigned base address in heap.
-    :arg Size: Immediate unsigned byte count for range to verify.
-    :result iPtr a: Absolute address corresponding to ``p``.
+.. autoinst:: heap_addr
 
 A small example using heaps::
 
diff --git a/cranelift/filetests/parser/tiny.cton b/cranelift/filetests/parser/tiny.cton
index e89efb4cbe..92842cd140 100644
--- a/cranelift/filetests/parser/tiny.cton
+++ b/cranelift/filetests/parser/tiny.cton
@@ -114,3 +114,17 @@ ebb0:
 ; nextln: $v2 = stack_load.i32 $ss10+4
 ; nextln: stack_store $v1, $ss10+2
 ; nextln: stack_store $v2, $ss2
+
+; Heap access instructions.
+function heap(i32) {
+    ; TODO: heap0 = heap %foo
+ebb0(v1: i32):
+    v2 = heap_load.f32 v1
+    v3 = heap_load.f32 v1+12
+    heap_store v3, v1
+}
+; sameln: function heap(i32) {
+; nextln: ebb0($v1: i32):
+; nextln:     $v2 = heap_load.f32 $v1
+; nextln:     $v3 = heap_load.f32 $v1+12
+; nextln:     heap_store $v3, $v1
diff --git a/lib/cretonne/meta/base/formats.py b/lib/cretonne/meta/base/formats.py
index c840e1b360..767be3be7e 100644
--- a/lib/cretonne/meta/base/formats.py
+++ b/lib/cretonne/meta/base/formats.py
@@ -8,7 +8,8 @@ in this module.
 from __future__ import absolute_import
 from cdsl.formats import InstructionFormat
 from cdsl.operands import VALUE, VARIABLE_ARGS
-from .immediates import imm64, uimm8, ieee32, ieee64, offset32, intcc, floatcc
+from .immediates import imm64, uimm8, ieee32, ieee64, offset32, uoffset32
+from .immediates import intcc, floatcc
 from .entities import ebb, sig_ref, func_ref, jump_table, stack_slot
 
 Nullary = InstructionFormat()
@@ -55,5 +56,10 @@ IndirectCall = InstructionFormat(
 StackLoad = InstructionFormat(stack_slot, offset32)
 StackStore = InstructionFormat(VALUE, stack_slot, offset32)
 
+# Accessing a WebAssembly heap.
+# TODO: Add a reference to a `heap` declared in the preamble.
+HeapLoad = InstructionFormat(VALUE, uoffset32)
+HeapStore = InstructionFormat(VALUE, VALUE, uoffset32)
+
 # Finally extract the names of global variables in this module.
 InstructionFormat.extract_names(globals())
diff --git a/lib/cretonne/meta/base/instructions.py b/lib/cretonne/meta/base/instructions.py
index 29d2f44a16..d3de015311 100644
--- a/lib/cretonne/meta/base/instructions.py
+++ b/lib/cretonne/meta/base/instructions.py
@@ -9,7 +9,7 @@ from cdsl.operands import Operand, VARIABLE_ARGS
 from cdsl.typevar import TypeVar
 from cdsl.instructions import Instruction, InstructionGroup
 from base.types import i8, f32, f64, b1
-from base.immediates import imm64, uimm8, ieee32, ieee64, offset32
+from base.immediates import imm64, uimm8, ieee32, ieee64, offset32, uoffset32
 from base.immediates import intcc, floatcc
 from base import entities
 import base.formats  # noqa
@@ -209,6 +209,7 @@ SS = Operand('SS', entities.stack_slot)
 Offset = Operand('Offset', offset32, 'In-bounds offset into stack slot')
 x = Operand('x', Mem, doc='Value to be stored')
 a = Operand('a', Mem, doc='Value loaded')
+p = Operand('p', iAddr)
 addr = Operand('addr', iAddr)
 
 stack_load = Instruction(
@@ -247,6 +248,44 @@ stack_addr = Instruction(
         """,
         ins=(SS, Offset), outs=addr)
 
+#
+# WebAssembly bounds-checked heap accesses.
+#
+# TODO: Add a `heap` operand that selects between multiple heaps.
+# TODO: Should the immediate offset be a `u32`?
+# TODO: Distinguish between `iAddr` for a heap and for a target address? i.e.,
+#       32-bit WebAssembly on a 64-bit target has two different types.
+
+Offset = Operand('Offset', uoffset32, 'Unsigned offset to effective address')
+
+heap_load = Instruction(
+        'heap_load', r"""
+        Load a value at the address :math:`p + Offset` in the heap H.
+
+        Trap if the heap access would be out of bounds.
+        """,
+        ins=(p, Offset), outs=a)
+
+heap_store = Instruction(
+        'heap_store', r"""
+        Store a value at the address :math:`p + Offset` in the heap H.
+
+        Trap if the heap access would be out of bounds.
+        """,
+        ins=(x, p, Offset))
+
+heap_addr = Instruction(
+        'heap_addr', r"""
+        Bounds check and compute absolute address of heap memory.
+
+        Verify that the address range ``p .. p + Size - 1`` is valid in the
+        heap H, and trap if not.
+
+        Convert the heap-relative address in ``p`` to a real absolute address
+        and return it.
+        """,
+        ins=(p, Offset), outs=addr)
+
 #
 # Materializing constants.
 #
diff --git a/lib/cretonne/src/ir/builder.rs b/lib/cretonne/src/ir/builder.rs
index e15a93bf30..8b95f20272 100644
--- a/lib/cretonne/src/ir/builder.rs
+++ b/lib/cretonne/src/ir/builder.rs
@@ -6,7 +6,7 @@
 use ir::types;
 use ir::{InstructionData, DataFlowGraph, Cursor};
 use ir::{Opcode, Type, Inst, Value, Ebb, JumpTable, SigRef, FuncRef, StackSlot, ValueList};
-use ir::immediates::{Imm64, Uimm8, Ieee32, Ieee64, Offset32};
+use ir::immediates::{Imm64, Uimm8, Ieee32, Ieee64, Offset32, Uoffset32};
 use ir::condcodes::{IntCC, FloatCC};
 
 /// Base trait for instruction builders.
diff --git a/lib/cretonne/src/ir/instructions.rs b/lib/cretonne/src/ir/instructions.rs
index a0ff3a3be4..5e8d66a09c 100644
--- a/lib/cretonne/src/ir/instructions.rs
+++ b/lib/cretonne/src/ir/instructions.rs
@@ -11,7 +11,7 @@ use std::str::FromStr;
 use std::ops::{Deref, DerefMut};
 
 use ir::{Value, Type, Ebb, JumpTable, SigRef, FuncRef, StackSlot};
-use ir::immediates::{Imm64, Uimm8, Ieee32, Ieee64, Offset32};
+use ir::immediates::{Imm64, Uimm8, Ieee32, Ieee64, Offset32, Uoffset32};
 use ir::condcodes::*;
 use ir::types;
 use ir::DataFlowGraph;
@@ -240,6 +240,18 @@ pub enum InstructionData {
         stack_slot: StackSlot,
         offset: Offset32,
     },
+    HeapLoad {
+        opcode: Opcode,
+        ty: Type,
+        arg: Value,
+        offset: Uoffset32,
+    },
+    HeapStore {
+        opcode: Opcode,
+        ty: Type,
+        args: [Value; 2],
+        offset: Uoffset32,
+    },
 }
 
 /// A variable list of `Value` operands used for function call arguments and passing arguments to
diff --git a/lib/cretonne/src/verifier.rs b/lib/cretonne/src/verifier.rs
index 29a40d55b9..b1b4429d1a 100644
--- a/lib/cretonne/src/verifier.rs
+++ b/lib/cretonne/src/verifier.rs
@@ -269,7 +269,9 @@ impl<'a> Verifier<'a> {
             &ExtractLane { .. } |
             &IntCompare { .. } |
             &IntCompareImm { .. } |
-            &FloatCompare { .. } => {}
+            &FloatCompare { .. } |
+            &HeapLoad { .. } |
+            &HeapStore { .. } => {}
         }
 
         Ok(())
diff --git a/lib/cretonne/src/write.rs b/lib/cretonne/src/write.rs
index 1ab481cdd1..f4b7de5f75 100644
--- a/lib/cretonne/src/write.rs
+++ b/lib/cretonne/src/write.rs
@@ -320,6 +320,8 @@ pub fn write_operands(w: &mut Write, dfg: &DataFlowGraph, inst: Inst) -> Result
             offset,
             ..
         } => write!(w, " {}, {}{}", arg, stack_slot, offset),
+        HeapLoad { arg, offset, .. } => write!(w, " {}{}", arg, offset),
+        HeapStore { args, offset, .. } => write!(w, " {}, {}{}", args[0], args[1], offset),
     }
 }
 
diff --git a/lib/reader/src/parser.rs b/lib/reader/src/parser.rs
index 8775f1f0b4..e813404130 100644
--- a/lib/reader/src/parser.rs
+++ b/lib/reader/src/parser.rs
@@ -227,15 +227,18 @@ impl<'a> Context<'a> {
                     InstructionData::IntCompareImm { ref mut arg, .. } |
                     InstructionData::Unary { ref mut arg, .. } |
                     InstructionData::UnarySplit { ref mut arg, .. } |
-                    InstructionData::StackStore { ref mut arg, .. } => {
+                    InstructionData::StackStore { ref mut arg, .. } |
+                    InstructionData::HeapLoad { ref mut arg, .. } => {
                         self.map.rewrite_value(arg, loc)?;
                     }
 
+                    // `args: Value[2]`
                     InstructionData::Binary { ref mut args, .. } |
                     InstructionData::BinaryOverflow { ref mut args, .. } |
                     InstructionData::InsertLane { ref mut args, .. } |
                     InstructionData::IntCompare { ref mut args, .. } |
-                    InstructionData::FloatCompare { ref mut args, .. } => {
+                    InstructionData::FloatCompare { ref mut args, .. } |
+                    InstructionData::HeapStore { ref mut args, .. } => {
                         self.map.rewrite_values(args, loc)?;
                     }
 
@@ -1710,6 +1713,28 @@ impl<'a> Parser<'a> {
                     offset: offset,
                 }
             }
+            InstructionFormat::HeapLoad => {
+                let addr = self.match_value("expected SSA value address")?;
+                let offset = self.optional_uoffset32()?;
+                InstructionData::HeapLoad {
+                    opcode: opcode,
+                    ty: VOID,
+                    arg: addr,
+                    offset: offset,
+                }
+            }
+            InstructionFormat::HeapStore => {
+                let arg = self.match_value("expected SSA value operand")?;
+                self.match_token(Token::Comma, "expected ',' between operands")?;
+                let addr = self.match_value("expected SSA value address")?;
+                let offset = self.optional_uoffset32()?;
+                InstructionData::HeapStore {
+                    opcode: opcode,
+                    ty: VOID,
+                    args: [arg, addr],
+                    offset: offset,
+                }
+            }
         };
         Ok(idata)
     }