diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
index 042e3f2332..594f280f03 100644
--- a/src/cmd/compile/internal/inline/inl.go
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -179,6 +179,8 @@ func CanInline(fn *ir.Func) {
 		Cost: inlineMaxBudget - visitor.budget,
 		Dcl:  pruneUnusedAutos(n.Defn.(*ir.Func).Dcl, &visitor),
 		Body: inlcopylist(fn.Body),
+
+		CanDelayResults: canDelayResults(fn),
 	}
 
 	if base.Flag.LowerM > 1 {
@@ -191,6 +193,38 @@ func CanInline(fn *ir.Func) {
 	}
 }
 
+// canDelayResults reports whether inlined calls to fn can delay
+// declaring the result parameter until the "return" statement.
+func canDelayResults(fn *ir.Func) bool {
+	// We can delay declaring+initializing result parameters if:
+	// (1) there's exactly one "return" statement in the inlined function;
+	// (2) it's not an empty return statement (#44355); and
+	// (3) the result parameters aren't named.
+
+	nreturns := 0
+	ir.VisitList(fn.Body, func(n ir.Node) {
+		if n, ok := n.(*ir.ReturnStmt); ok {
+			nreturns++
+			if len(n.Results) == 0 {
+				nreturns++ // empty return statement (case 2)
+			}
+		}
+	})
+
+	if nreturns != 1 {
+		return false // not exactly one return statement (case 1)
+	}
+
+	// temporaries for return values.
+	for _, param := range fn.Type().Results().FieldSlice() {
+		if sym := types.OrigSym(param.Sym); sym != nil && !sym.IsBlank() {
+			return false // found a named result parameter (case 3)
+		}
+	}
+
+	return true
+}
+
 // Inline_Flood marks n's inline body for export and recursively ensures
 // all called functions are marked too.
 func Inline_Flood(n *ir.Name, exportsym func(*ir.Name)) {
@@ -740,6 +774,11 @@ var inlgen int
 // when producing output for debugging the compiler itself.
 var SSADumpInline = func(*ir.Func) {}
 
+// NewInline allows the inliner implementation to be overridden.
+// If it returns nil, the legacy inliner will handle this call
+// instead.
+var NewInline = func(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr { return nil }
+
 // If n is a call node (OCALLFUNC or OCALLMETH), and fn is an ONAME node for a
 // function with an inlinable body, return an OINLCALL node that can replace n.
 // The returned node's Ninit has the parameter assignments, the Nbody is the
@@ -796,30 +835,64 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 
 	typecheck.FixVariadicCall(n)
 
-	if base.Debug.TypecheckInl == 0 {
-		typecheck.ImportedBody(fn)
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+
+	sym := fn.Linksym()
+	inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
+
+	if base.Flag.GenDwarfInl > 0 {
+		if !sym.WasInlined() {
+			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
+			sym.Set(obj.AttrWasInlined, true)
+		}
 	}
 
-	// We have a function node, and it has an inlineable body.
-	if base.Flag.LowerM > 1 {
-		fmt.Printf("%v: inlining call to %v %v { %v }\n", ir.Line(n), fn.Sym(), fn.Type(), ir.Nodes(fn.Inl.Body))
-	} else if base.Flag.LowerM != 0 {
+	if base.Flag.LowerM != 0 {
 		fmt.Printf("%v: inlining call to %v\n", ir.Line(n), fn)
 	}
 	if base.Flag.LowerM > 2 {
 		fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
 	}
 
+	res := NewInline(n, fn, inlIndex)
+	if res == nil {
+		res = oldInline(n, fn, inlIndex)
+	}
+
+	// transitive inlining
+	// might be nice to do this before exporting the body,
+	// but can't emit the body with inlining expanded.
+	// instead we emit the things that the body needs
+	// and each use must redo the inlining.
+	// luckily these are small.
+	ir.EditChildren(res, edit)
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), res)
+	}
+
+	return res
+}
+
+// oldInline creates an InlinedCallExpr to replace the given call
+// expression. fn is the callee function to be inlined. inlIndex is
+// the inlining tree position index, for use with src.NewInliningBase
+// when rewriting positions.
+func oldInline(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	if base.Debug.TypecheckInl == 0 {
+		typecheck.ImportedBody(fn)
+	}
+
 	SSADumpInline(fn)
 
-	ninit := n.Init()
+	ninit := call.Init()
 
 	// For normal function calls, the function callee expression
 	// may contain side effects (e.g., added by addinit during
 	// inlconv2expr or inlconv2list). Make sure to preserve these,
 	// if necessary (#42703).
-	if n.Op() == ir.OCALLFUNC {
-		callee := n.X
+	if call.Op() == ir.OCALLFUNC {
+		callee := call.X
 		for callee.Op() == ir.OCONVNOP {
 			conv := callee.(*ir.ConvExpr)
 			ninit.Append(ir.TakeInit(conv)...)
@@ -857,25 +930,6 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	}
 
 	// We can delay declaring+initializing result parameters if:
-	// (1) there's exactly one "return" statement in the inlined function;
-	// (2) it's not an empty return statement (#44355); and
-	// (3) the result parameters aren't named.
-	delayretvars := true
-
-	nreturns := 0
-	ir.VisitList(ir.Nodes(fn.Inl.Body), func(n ir.Node) {
-		if n, ok := n.(*ir.ReturnStmt); ok {
-			nreturns++
-			if len(n.Results) == 0 {
-				delayretvars = false // empty return statement (case 2)
-			}
-		}
-	})
-
-	if nreturns != 1 {
-		delayretvars = false // not exactly one return statement (case 1)
-	}
-
 	// temporaries for return values.
 	var retvars []ir.Node
 	for i, t := range fn.Type().Results().Fields().Slice() {
@@ -885,7 +939,6 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 			m = inlvar(n)
 			m = typecheck.Expr(m).(*ir.Name)
 			inlvars[n] = m
-			delayretvars = false // found a named result parameter (case 3)
 		} else {
 			// anonymous return values, synthesize names for use in assignment that replaces return
 			m = retvar(t, i)
@@ -908,14 +961,14 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 	// Assign arguments to the parameters' temp names.
 	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
 	as.Def = true
-	if n.Op() == ir.OCALLMETH {
-		sel := n.X.(*ir.SelectorExpr)
+	if call.Op() == ir.OCALLMETH {
+		sel := call.X.(*ir.SelectorExpr)
 		if sel.X == nil {
-			base.Fatalf("method call without receiver: %+v", n)
+			base.Fatalf("method call without receiver: %+v", call)
 		}
 		as.Rhs.Append(sel.X)
 	}
-	as.Rhs.Append(n.Args...)
+	as.Rhs.Append(call.Args...)
 
 	if recv := fn.Type().Recv(); recv != nil {
 		as.Lhs.Append(inlParam(recv, as, inlvars))
@@ -928,7 +981,7 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 		ninit.Append(typecheck.Stmt(as))
 	}
 
-	if !delayretvars {
+	if !fn.Inl.CanDelayResults {
 		// Zero the return parameters.
 		for _, n := range retvars {
 			ninit.Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
@@ -941,40 +994,21 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 
 	inlgen++
 
-	parent := -1
-	if b := base.Ctxt.PosTable.Pos(n.Pos()).Base(); b != nil {
-		parent = b.InliningIndex()
-	}
-
-	sym := fn.Linksym()
-	newIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
-
 	// Add an inline mark just before the inlined body.
 	// This mark is inline in the code so that it's a reasonable spot
 	// to put a breakpoint. Not sure if that's really necessary or not
 	// (in which case it could go at the end of the function instead).
 	// Note issue 28603.
-	inlMark := ir.NewInlineMarkStmt(base.Pos, types.BADWIDTH)
-	inlMark.SetPos(n.Pos().WithIsStmt())
-	inlMark.Index = int64(newIndex)
-	ninit.Append(inlMark)
-
-	if base.Flag.GenDwarfInl > 0 {
-		if !sym.WasInlined() {
-			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
-			sym.Set(obj.AttrWasInlined, true)
-		}
-	}
+	ninit.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(inlIndex)))
 
 	subst := inlsubst{
-		retlabel:     retlabel,
-		retvars:      retvars,
-		delayretvars: delayretvars,
-		inlvars:      inlvars,
-		defnMarker:   ir.NilExpr{},
-		bases:        make(map[*src.PosBase]*src.PosBase),
-		newInlIndex:  newIndex,
-		fn:           fn,
+		retlabel:    retlabel,
+		retvars:     retvars,
+		inlvars:     inlvars,
+		defnMarker:  ir.NilExpr{},
+		bases:       make(map[*src.PosBase]*src.PosBase),
+		newInlIndex: inlIndex,
+		fn:          fn,
 	}
 	subst.edit = subst.node
 
@@ -995,26 +1029,11 @@ func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]b
 
 	//dumplist("ninit post", ninit);
 
-	call := ir.NewInlinedCallExpr(base.Pos, nil, nil)
-	*call.PtrInit() = ninit
-	call.Body = body
-	call.ReturnVars = retvars
-	call.SetType(n.Type())
-	call.SetTypecheck(1)
-
-	// transitive inlining
-	// might be nice to do this before exporting the body,
-	// but can't emit the body with inlining expanded.
-	// instead we emit the things that the body needs
-	// and each use must redo the inlining.
-	// luckily these are small.
-	ir.EditChildren(call, edit)
-
-	if base.Flag.LowerM > 2 {
-		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(call), call)
-	}
-
-	return call
+	res := ir.NewInlinedCallExpr(base.Pos, body, retvars)
+	res.SetInit(ninit)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+	return res
 }
 
 // Every time we expand a function we generate a new set of tmpnames,
@@ -1057,10 +1076,6 @@ type inlsubst struct {
 	// Temporary result variables.
 	retvars []ir.Node
 
-	// Whether result variables should be initialized at the
-	// "return" statement.
-	delayretvars bool
-
 	inlvars map[*ir.Name]*ir.Name
 	// defnMarker is used to mark a Node for reassignment.
 	// inlsubst.clovar set this during creating new ONAME.
@@ -1353,7 +1368,7 @@ func (subst *inlsubst) node(n ir.Node) ir.Node {
 			}
 			as.Rhs = subst.list(n.Results)
 
-			if subst.delayretvars {
+			if subst.fn.Inl.CanDelayResults {
 				for _, n := range as.Lhs {
 					as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
 					n.Name().Defn = as
diff --git a/src/cmd/compile/internal/ir/func.go b/src/cmd/compile/internal/ir/func.go
index a4231a1bcb..ca6c8eca8b 100644
--- a/src/cmd/compile/internal/ir/func.go
+++ b/src/cmd/compile/internal/ir/func.go
@@ -166,6 +166,11 @@ type Inline struct {
 	// another package is imported.
 	Dcl  []*Name
 	Body []Node
+
+	// CanDelayResults reports whether it's safe for the inliner to delay
+	// initializing the result parameters until immediately before the
+	// "return" statement.
+	CanDelayResults bool
 }
 
 // A Mark represents a scope boundary.
diff --git a/src/cmd/compile/internal/typecheck/iexport.go b/src/cmd/compile/internal/typecheck/iexport.go
index e798ce5143..f49718d442 100644
--- a/src/cmd/compile/internal/typecheck/iexport.go
+++ b/src/cmd/compile/internal/typecheck/iexport.go
@@ -1313,6 +1313,7 @@ func (w *exportWriter) funcExt(n *ir.Name) {
 	}
 	if n.Func.Inl != nil {
 		w.uint64(1 + uint64(n.Func.Inl.Cost))
+		w.bool(n.Func.Inl.CanDelayResults)
 		if n.Func.ExportInline() || n.Type().HasTParam() {
 			w.p.doInline(n)
 		}
diff --git a/src/cmd/compile/internal/typecheck/iimport.go b/src/cmd/compile/internal/typecheck/iimport.go
index 16b3e7ceba..cca14a0d91 100644
--- a/src/cmd/compile/internal/typecheck/iimport.go
+++ b/src/cmd/compile/internal/typecheck/iimport.go
@@ -927,7 +927,8 @@ func (r *importReader) funcExt(n *ir.Name) {
 	// Inline body.
 	if u := r.uint64(); u > 0 {
 		n.Func.Inl = &ir.Inline{
-			Cost: int32(u - 1),
+			Cost:            int32(u - 1),
+			CanDelayResults: r.bool(),
 		}
 		n.Func.Endlineno = r.pos()
 	}
diff --git a/test/fixedbugs/issue24651a.go b/test/fixedbugs/issue24651a.go
index 6c7bf30908..1bfe8ac1ce 100644
--- a/test/fixedbugs/issue24651a.go
+++ b/test/fixedbugs/issue24651a.go
@@ -21,5 +21,5 @@ var x = 5
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
 	println("Foo(", x, ")=", Foo(x))
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/fixedbugs/issue24651b.go b/test/fixedbugs/issue24651b.go
index aa88a6787b..2af54fc4b5 100644
--- a/test/fixedbugs/issue24651b.go
+++ b/test/fixedbugs/issue24651b.go
@@ -19,6 +19,6 @@ var x = 5
 
 //go:noinline Provide a clean, constant reason for not inlining main
 func main() { // ERROR "cannot inline main: marked go:noinline$"
-	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
-	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar func\(int\) int { return x \* \(x \+ 1\) \* \(x \+ 2\) }$"
+	println("Foo(", x, ")=", Foo(x)) // ERROR "inlining call to Foo"
+	println("Bar(", x, ")=", Bar(x)) // ERROR "inlining call to Bar"
 }
diff --git a/test/inline_big.go b/test/inline_big.go
index 68e1101d3b..83672753f7 100644
--- a/test/inline_big.go
+++ b/test/inline_big.go
@@ -1023,7 +1023,7 @@ func f(a []int) int { // ERROR "cannot inline f:.*" "a does not escape"
 	a[997] = 0
 	a[998] = 0
 	a[999] = 0
-	x := small(a)  // ERROR "inlining call to small .*"
+	x := small(a)  // ERROR "inlining call to small"
 	y := medium(a) // The crux of this test: medium is not inlined.
 	return x + y
 }