diff --git a/cranelift/filetests/isa/intel/binary64.cton b/cranelift/filetests/isa/intel/binary64.cton
index 8ac8deb58e..0b546961d8 100644
--- a/cranelift/filetests/isa/intel/binary64.cton
+++ b/cranelift/filetests/isa/intel/binary64.cton
@@ -634,6 +634,23 @@ ebb1:
     return
 }
 
+; Test for the encoding of outgoing_arg stack slots.
+function %outargs() {
+    ss0 = incoming_arg 16, offset -16
+    ss1 = outgoing_arg 8, offset 8
+    ss2 = outgoing_arg 8, offset 0
+
+ebb0:
+    [-,%rcx]            v1 = iconst.i64 1
+
+    ; asm: movq %rcx, 8(%rsp)
+    [-,ss1]             v10 = spill v1              ; bin: 48 89 8c 24 00000008
+    ; asm: movq %rcx, (%rsp)
+    [-,ss2]             v11 = spill v1              ; bin: 48 89 8c 24 00000000
+
+    return
+}
+
 ; Tests for i32 instructions in 64-bit mode.
 ;
 ; Note that many i32 instructions can be encoded both with and without a REX
diff --git a/lib/cretonne/src/isa/stack.rs b/lib/cretonne/src/isa/stack.rs
index 907afe0208..730db28e18 100644
--- a/lib/cretonne/src/isa/stack.rs
+++ b/lib/cretonne/src/isa/stack.rs
@@ -4,7 +4,7 @@
 //! defined in this module expresses the low-level details of accessing a stack slot from an
 //! encoded instruction.
 
-use ir::stackslot::{StackSlots, StackOffset};
+use ir::stackslot::{StackSlots, StackOffset, StackSlotKind};
 use ir::StackSlot;
 
 /// A method for referencing a stack slot in the current stack frame.
@@ -38,12 +38,19 @@ impl StackRef {
         let size = frame.frame_size.expect(
             "Stack layout must be computed before referencing stack slots",
         );
-
-        // Offset where SP is pointing. (All ISAs have stacks growing downwards.)
-        let sp_offset = -(size as StackOffset);
+        let slot = &frame[ss];
+        let offset = if slot.kind == StackSlotKind::OutgoingArg {
+            // Outgoing argument slots have offsets relative to our stack pointer.
+            slot.offset
+        } else {
+            // All other slots have offsets relative to our caller's stack frame.
+            // Offset where SP is pointing. (All ISAs have stacks growing downwards.)
+            let sp_offset = -(size as StackOffset);
+            slot.offset - sp_offset
+        };
         StackRef {
             base: StackBase::SP,
-            offset: frame[ss].offset - sp_offset,
+            offset,
         }
     }
 }