diff --git a/src/cmd/compile/internal/gc/closure.go b/src/cmd/compile/internal/gc/closure.go
index 50d679ea974..04f3e669e27 100644
--- a/src/cmd/compile/internal/gc/closure.go
+++ b/src/cmd/compile/internal/gc/closure.go
@@ -243,6 +243,9 @@ func makeclosure(func_ *Node) *Node {
 	return xfunc
 }
 
+// capturevarscomplete is set to true when the capturevars phase is done.
+var capturevarscomplete bool
+
 // capturevars is called in a separate phase after all typechecking is done.
 // It decides whether each variable captured by a closure should be captured
 // by value or by reference.
diff --git a/src/cmd/compile/internal/gc/main.go b/src/cmd/compile/internal/gc/main.go
index f67822e6136..a2472fa08bb 100644
--- a/src/cmd/compile/internal/gc/main.go
+++ b/src/cmd/compile/internal/gc/main.go
@@ -33,15 +33,16 @@ var (
 )
 
 var (
-	Debug_append   int
-	Debug_asm      bool
-	Debug_closure  int
-	debug_dclstack int
-	Debug_panic    int
-	Debug_slice    int
-	Debug_vlog     bool
-	Debug_wb       int
-	Debug_pctab    string
+	Debug_append       int
+	Debug_asm          bool
+	Debug_closure      int
+	Debug_compilelater int
+	debug_dclstack     int
+	Debug_panic        int
+	Debug_slice        int
+	Debug_vlog         bool
+	Debug_wb           int
+	Debug_pctab        string
 )
 
 // Debug arguments.
@@ -56,6 +57,7 @@ var debugtab = []struct {
 }{
 	{"append", "print information about append compilation", &Debug_append},
 	{"closure", "print information about closure compilation", &Debug_closure},
+	{"compilelater", "compile functions as late as possible", &Debug_compilelater},
 	{"disablenil", "disable nil checks", &disable_checknil},
 	{"dclstack", "run internal dclstack check", &debug_dclstack},
 	{"gcprog", "print dump of GC programs", &Debug_gcprog},
@@ -493,6 +495,7 @@ func Main(archInit func(*Arch)) {
 			capturevars(n)
 		}
 	}
+	capturevarscomplete = true
 
 	Curfn = nil
 
diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 91cd1e35d78..fdf3bf78474 100644
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -226,7 +226,7 @@ func compile(fn *Node) {
 // they are enqueued in compilequeue,
 // which is drained by compileFunctions.
 func compilenow() bool {
-	return nBackendWorkers == 1
+	return nBackendWorkers == 1 && Debug_compilelater == 0
 }
 
 // compileSSA builds an SSA backend function,
diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go
index 5e92e926e3d..b02bc659be3 100644
--- a/src/cmd/compile/internal/gc/typecheck.go
+++ b/src/cmd/compile/internal/gc/typecheck.go
@@ -815,7 +815,11 @@ OpSwitch:
 		var l *Node
 		for l = n.Left; l != r; l = l.Left {
 			l.SetAddrtaken(true)
-			if l.IsClosureVar() {
+			if l.IsClosureVar() && !capturevarscomplete {
+				// Mark the original variable as Addrtaken so that capturevars
+				// knows not to pass it by value.
+				// But if the capturevars phase is complete, don't touch it,
+				// in case l.Name's containing function has not yet been compiled.
 				l.Name.Defn.SetAddrtaken(true)
 			}
 		}
@@ -824,7 +828,8 @@ OpSwitch:
 			Fatalf("found non-orig name node %v", l)
 		}
 		l.SetAddrtaken(true)
-		if l.IsClosureVar() {
+		if l.IsClosureVar() && !capturevarscomplete {
+			// See comments above about closure variables.
 			l.Name.Defn.SetAddrtaken(true)
 		}
 		n.Left = defaultlit(n.Left, nil)
diff --git a/test/fixedbugs/issue20250.go b/test/fixedbugs/issue20250.go
new file mode 100644
index 00000000000..f24710a0c30
--- /dev/null
+++ b/test/fixedbugs/issue20250.go
@@ -0,0 +1,24 @@
+// errorcheck -0 -live -d=compilelater
+
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Issue 20250: liveness differed with concurrent compilation
+// due to propagation of addrtaken to outer variables for
+// closure variables.
+
+package p
+
+type T struct {
+	s string
+}
+
+func f(a T) { // ERROR "live at entry to f: a"
+	var e interface{}
+	func() { // ERROR "live at entry to f.func1: &e a"
+		e = a.s // ERROR "live at call to convT2Estring: &e a" "live at call to writebarrierptr: a"
+	}() // ERROR "live at call to f.func1: e$"
+	// Before the fix, both a and e were live at the previous line.
+	_ = e
+}