diff --git a/src/fmt/errors_test.go b/src/fmt/errors_test.go
index 0183ba77e5b0f..39f247e06d1ca 100644
--- a/src/fmt/errors_test.go
+++ b/src/fmt/errors_test.go
@@ -157,8 +157,8 @@ func TestErrorFormatter(t *testing.T) {
 		want: "fallback:" +
 			"\n    somefile.go:123" +
 			"\n  - file does not exist:" +
-			"\n    os.init" +
-			"\n        .+/os/error.go:\\d\\d",
+			"\n    .*" +
+			"\n        .+.go:\\d+",
 		regexp: true,
 	}, {
 		err: &wrapped{"outer",
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 31a5d2741d77f..df1d8dd3b3732 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -146,8 +146,9 @@ var pkgDeps = map[string][]string{
 	// End of linear dependency definitions.
 
 	// Operating system access.
-	"syscall":                           {"L0", "internal/race", "internal/syscall/windows/sysdll", "syscall/js", "unicode/utf16"},
+	"syscall":                           {"L0", "internal/oserror", "internal/race", "internal/syscall/windows/sysdll", "syscall/js", "unicode/utf16"},
 	"syscall/js":                        {"L0"},
+	"internal/oserror":                  {"L0"},
 	"internal/syscall/unix":             {"L0", "syscall"},
 	"internal/syscall/windows":          {"L0", "syscall", "internal/syscall/windows/sysdll"},
 	"internal/syscall/windows/registry": {"L0", "syscall", "internal/syscall/windows/sysdll", "unicode/utf16"},
@@ -167,7 +168,7 @@ var pkgDeps = map[string][]string{
 
 	"internal/poll":    {"L0", "internal/race", "syscall", "time", "unicode/utf16", "unicode/utf8", "internal/syscall/windows"},
 	"internal/testlog": {"L0"},
-	"os":               {"L1", "os", "syscall", "time", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/testlog"},
+	"os":               {"L1", "os", "syscall", "time", "internal/oserror", "internal/poll", "internal/syscall/windows", "internal/syscall/unix", "internal/testlog"},
 	"path/filepath":    {"L2", "os", "syscall", "internal/syscall/windows"},
 	"io/ioutil":        {"L2", "os", "path/filepath", "time"},
 	"os/exec":          {"L2", "os", "context", "path/filepath", "syscall"},
diff --git a/src/internal/oserror/errors.go b/src/internal/oserror/errors.go
new file mode 100644
index 0000000000000..66ed7faaba27e
--- /dev/null
+++ b/src/internal/oserror/errors.go
@@ -0,0 +1,20 @@
+// Copyright 2019 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.
+
+// Package oserror defines errors values used in the os package.
+//
+// These types are defined here to permit the syscall package to reference them.
+package oserror
+
+import "errors"
+
+var (
+	ErrInvalid    = errors.New("invalid argument")
+	ErrPermission = errors.New("permission denied")
+	ErrExist      = errors.New("file already exists")
+	ErrNotExist   = errors.New("file does not exist")
+	ErrClosed     = errors.New("file already closed")
+	ErrTemporary  = errors.New("temporary error")
+	ErrTimeout    = errors.New("deadline exceeded")
+)
diff --git a/src/os/error.go b/src/os/error.go
index 16e5cb5786b59..4cf35f2b773f2 100644
--- a/src/os/error.go
+++ b/src/os/error.go
@@ -5,20 +5,35 @@
 package os
 
 import (
-	"errors"
+	"internal/oserror"
 	"internal/poll"
 )
 
 // Portable analogs of some common system call errors.
+//
+// Errors returned from this package may be tested against these errors
+// with errors.Is.
 var (
-	ErrInvalid    = errors.New("invalid argument") // methods on File will return this error when the receiver is nil
-	ErrPermission = errors.New("permission denied")
-	ErrExist      = errors.New("file already exists")
-	ErrNotExist   = errors.New("file does not exist")
-	ErrClosed     = errors.New("file already closed")
-	ErrNoDeadline = poll.ErrNoDeadline
+	// ErrInvalid indicates an invalid argument.
+	// Methods on File will return this error when the receiver is nil.
+	ErrInvalid = errInvalid() // "invalid argument"
+
+	ErrPermission = errPermission() // "permission denied"
+	ErrExist      = errExist()      // "file already exists"
+	ErrNotExist   = errNotExist()   // "file does not exist"
+	ErrClosed     = errClosed()     // "file already closed"
+	ErrTimeout    = errTimeout()    // "deadline exceeded"
+	ErrNoDeadline = errNoDeadline() // "file type does not support deadline"
 )
 
+func errInvalid() error    { return oserror.ErrInvalid }
+func errPermission() error { return oserror.ErrPermission }
+func errExist() error      { return oserror.ErrExist }
+func errNotExist() error   { return oserror.ErrNotExist }
+func errClosed() error     { return oserror.ErrClosed }
+func errTimeout() error    { return oserror.ErrTimeout }
+func errNoDeadline() error { return poll.ErrNoDeadline }
+
 type timeout interface {
 	Timeout() bool
 }
@@ -48,6 +63,8 @@ type SyscallError struct {
 
 func (e *SyscallError) Error() string { return e.Syscall + ": " + e.Err.Error() }
 
+func (e *SyscallError) Unwrap() error { return e.Err }
+
 // Timeout reports whether this error represents a timeout.
 func (e *SyscallError) Timeout() bool {
 	t, ok := e.Err.(timeout)
@@ -68,21 +85,21 @@ func NewSyscallError(syscall string, err error) error {
 // that a file or directory already exists. It is satisfied by ErrExist as
 // well as some syscall errors.
 func IsExist(err error) bool {
-	return isExist(err)
+	return underlyingErrorIs(err, ErrExist)
 }
 
 // IsNotExist returns a boolean indicating whether the error is known to
 // report that a file or directory does not exist. It is satisfied by
 // ErrNotExist as well as some syscall errors.
 func IsNotExist(err error) bool {
-	return isNotExist(err)
+	return underlyingErrorIs(err, ErrNotExist)
 }
 
 // IsPermission returns a boolean indicating whether the error is known to
 // report that permission is denied. It is satisfied by ErrPermission as well
 // as some syscall errors.
 func IsPermission(err error) bool {
-	return isPermission(err)
+	return underlyingErrorIs(err, ErrPermission)
 }
 
 // IsTimeout returns a boolean indicating whether the error is known
@@ -92,6 +109,18 @@ func IsTimeout(err error) bool {
 	return ok && terr.Timeout()
 }
 
+func underlyingErrorIs(err, target error) bool {
+	// Note that this function is not errors.Is:
+	// underlyingError only unwraps the specific error-wrapping types
+	// that it historically did, not all errors.Wrapper implementations.
+	err = underlyingError(err)
+	if err == target {
+		return true
+	}
+	e, ok := err.(interface{ Is(error) bool })
+	return ok && e.Is(target)
+}
+
 // underlyingError returns the underlying error for known os error types.
 func underlyingError(err error) error {
 	switch err := err.(type) {
diff --git a/src/os/error_plan9.go b/src/os/error_plan9.go
deleted file mode 100644
index b82bf0dea37c6..0000000000000
--- a/src/os/error_plan9.go
+++ /dev/null
@@ -1,44 +0,0 @@
-// Copyright 2011 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.
-
-package os
-
-func isExist(err error) bool {
-	return checkErrMessageContent(err, "exists", "is a directory")
-}
-
-func isNotExist(err error) bool {
-	return checkErrMessageContent(err, "does not exist", "not found",
-		"has been removed", "no parent")
-}
-
-func isPermission(err error) bool {
-	return checkErrMessageContent(err, "permission denied")
-}
-
-// checkErrMessageContent checks if err message contains one of msgs.
-func checkErrMessageContent(err error, msgs ...string) bool {
-	if err == nil {
-		return false
-	}
-	err = underlyingError(err)
-	for _, msg := range msgs {
-		if contains(err.Error(), msg) {
-			return true
-		}
-	}
-	return false
-}
-
-// contains is a local version of strings.Contains. It knows len(sep) > 1.
-func contains(s, sep string) bool {
-	n := len(sep)
-	c := sep[0]
-	for i := 0; i+n <= len(s); i++ {
-		if s[i] == c && s[i:i+n] == sep {
-			return true
-		}
-	}
-	return false
-}
diff --git a/src/os/error_test.go b/src/os/error_test.go
index 0e3570996ec9d..a03bd28b9ae90 100644
--- a/src/os/error_test.go
+++ b/src/os/error_test.go
@@ -27,7 +27,7 @@ func TestErrIsExist(t *testing.T) {
 		t.Fatal("Open should have failed")
 		return
 	}
-	if s := checkErrorPredicate("os.IsExist", os.IsExist, err); s != "" {
+	if s := checkErrorPredicate("os.IsExist", os.IsExist, err, os.ErrExist); s != "" {
 		t.Fatal(s)
 		return
 	}
@@ -39,7 +39,7 @@ func testErrNotExist(name string) string {
 		f.Close()
 		return "Open should have failed"
 	}
-	if s := checkErrorPredicate("os.IsNotExist", os.IsNotExist, err); s != "" {
+	if s := checkErrorPredicate("os.IsNotExist", os.IsNotExist, err, os.ErrNotExist); s != "" {
 		return s
 	}
 
@@ -47,7 +47,7 @@ func testErrNotExist(name string) string {
 	if err == nil {
 		return "Chdir should have failed"
 	}
-	if s := checkErrorPredicate("os.IsNotExist", os.IsNotExist, err); s != "" {
+	if s := checkErrorPredicate("os.IsNotExist", os.IsNotExist, err, os.ErrNotExist); s != "" {
 		return s
 	}
 	return ""
@@ -74,10 +74,13 @@ func TestErrIsNotExist(t *testing.T) {
 	}
 }
 
-func checkErrorPredicate(predName string, pred func(error) bool, err error) string {
+func checkErrorPredicate(predName string, pred func(error) bool, err, target error) string {
 	if !pred(err) {
 		return fmt.Sprintf("%s does not work as expected for %#v", predName, err)
 	}
+	if !errors.Is(err, target) {
+		return fmt.Sprintf("errors.Is(%#v, %#v) = false, want true", err, target)
+	}
 	return ""
 }
 
@@ -108,9 +111,15 @@ func TestIsExist(t *testing.T) {
 		if is := os.IsExist(tt.err); is != tt.is {
 			t.Errorf("os.IsExist(%T %v) = %v, want %v", tt.err, tt.err, is, tt.is)
 		}
+		if is := errors.Is(tt.err, os.ErrExist); is != tt.is {
+			t.Errorf("errors.Is(%T %v, os.ErrExist) = %v, want %v", tt.err, tt.err, is, tt.is)
+		}
 		if isnot := os.IsNotExist(tt.err); isnot != tt.isnot {
 			t.Errorf("os.IsNotExist(%T %v) = %v, want %v", tt.err, tt.err, isnot, tt.isnot)
 		}
+		if isnot := errors.Is(tt.err, os.ErrNotExist); isnot != tt.isnot {
+			t.Errorf("errors.Is(%T %v, os.ErrNotExist) = %v, want %v", tt.err, tt.err, isnot, tt.isnot)
+		}
 	}
 }
 
@@ -130,6 +139,9 @@ func TestIsPermission(t *testing.T) {
 		if got := os.IsPermission(tt.err); got != tt.want {
 			t.Errorf("os.IsPermission(%#v) = %v; want %v", tt.err, got, tt.want)
 		}
+		if got := errors.Is(tt.err, os.ErrPermission); got != tt.want {
+			t.Errorf("errors.Is(%#v, os.ErrPermission) = %v; want %v", tt.err, got, tt.want)
+		}
 	}
 }
 
diff --git a/src/os/error_unix.go b/src/os/error_unix.go
deleted file mode 100644
index bb6bbcc1e6c15..0000000000000
--- a/src/os/error_unix.go
+++ /dev/null
@@ -1,24 +0,0 @@
-// Copyright 2009 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.
-
-// +build aix darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
-
-package os
-
-import "syscall"
-
-func isExist(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.EEXIST || err == syscall.ENOTEMPTY || err == ErrExist
-}
-
-func isNotExist(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.ENOENT || err == ErrNotExist
-}
-
-func isPermission(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.EACCES || err == syscall.EPERM || err == ErrPermission
-}
diff --git a/src/os/error_windows.go b/src/os/error_windows.go
deleted file mode 100644
index 02593b53fe4f6..0000000000000
--- a/src/os/error_windows.go
+++ /dev/null
@@ -1,28 +0,0 @@
-// Copyright 2012 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.
-
-package os
-
-import "syscall"
-
-func isExist(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.ERROR_ALREADY_EXISTS ||
-		err == syscall.ERROR_DIR_NOT_EMPTY ||
-		err == syscall.ERROR_FILE_EXISTS || err == ErrExist
-}
-
-const _ERROR_BAD_NETPATH = syscall.Errno(53)
-
-func isNotExist(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.ERROR_FILE_NOT_FOUND ||
-		err == _ERROR_BAD_NETPATH ||
-		err == syscall.ERROR_PATH_NOT_FOUND || err == ErrNotExist
-}
-
-func isPermission(err error) bool {
-	err = underlyingError(err)
-	return err == syscall.ERROR_ACCESS_DENIED || err == ErrPermission
-}
diff --git a/src/os/file.go b/src/os/file.go
index 5f715f4275293..a44263ee8acbc 100644
--- a/src/os/file.go
+++ b/src/os/file.go
@@ -98,6 +98,10 @@ func (e *LinkError) Error() string {
 	return e.Op + " " + e.Old + " " + e.New + ": " + e.Err.Error()
 }
 
+func (e *LinkError) Unwrap() error {
+	return e.Err
+}
+
 // Read reads up to len(b) bytes from the File.
 // It returns the number of bytes read and any error encountered.
 // At end of file, Read returns 0, io.EOF.
diff --git a/src/syscall/syscall_js.go b/src/syscall/syscall_js.go
index 2e1a9ec9f1fef..4dfcc6ed6415c 100644
--- a/src/syscall/syscall_js.go
+++ b/src/syscall/syscall_js.go
@@ -7,6 +7,7 @@
 package syscall
 
 import (
+	"internal/oserror"
 	"sync"
 	"unsafe"
 )
@@ -55,6 +56,22 @@ func (e Errno) Error() string {
 	return "errno " + itoa(int(e))
 }
 
+func (e Errno) Is(target error) bool {
+	switch target {
+	case oserror.ErrTemporary:
+		return e.Temporary()
+	case oserror.ErrTimeout:
+		return e.Timeout()
+	case oserror.ErrPermission:
+		return e == EACCES || e == EPERM
+	case oserror.ErrExist:
+		return e == EEXIST || e == ENOTEMPTY
+	case oserror.ErrNotExist:
+		return e == ENOENT
+	}
+	return false
+}
+
 func (e Errno) Temporary() bool {
 	return e == EINTR || e == EMFILE || e.Timeout()
 }
diff --git a/src/syscall/syscall_nacl.go b/src/syscall/syscall_nacl.go
index 1102cd66e3866..3fc504fd9f2c4 100644
--- a/src/syscall/syscall_nacl.go
+++ b/src/syscall/syscall_nacl.go
@@ -5,6 +5,7 @@
 package syscall
 
 import (
+	"internal/oserror"
 	"sync"
 	"unsafe"
 )
@@ -62,6 +63,22 @@ func (e Errno) Error() string {
 	return "errno " + itoa(int(e))
 }
 
+func (e Errno) Is(target error) bool {
+	switch target {
+	case oserror.ErrTemporary:
+		return e.Temporary()
+	case oserror.ErrTimeout:
+		return e.Timeout()
+	case oserror.ErrPermission:
+		return e == EACCES || e == EPERM
+	case oserror.ErrExist:
+		return e == EEXIST || e == ENOTEMPTY
+	case oserror.ErrNotExist:
+		return e == ENOENT
+	}
+	return false
+}
+
 func (e Errno) Temporary() bool {
 	return e == EINTR || e == EMFILE || e.Timeout()
 }
diff --git a/src/syscall/syscall_plan9.go b/src/syscall/syscall_plan9.go
index 48513c73c94b9..9b5a2940b07ae 100644
--- a/src/syscall/syscall_plan9.go
+++ b/src/syscall/syscall_plan9.go
@@ -11,7 +11,10 @@
 
 package syscall
 
-import "unsafe"
+import (
+	"internal/oserror"
+	"unsafe"
+)
 
 const ImplementsGetwd = true
 const bitSize16 = 2
@@ -24,6 +27,45 @@ func (e ErrorString) Error() string { return string(e) }
 // NewError converts s to an ErrorString, which satisfies the Error interface.
 func NewError(s string) error { return ErrorString(s) }
 
+func (e ErrorString) Is(target error) bool {
+	switch target {
+	case oserror.ErrTemporary:
+		return e.Temporary()
+	case oserror.ErrTimeout:
+		return e.Timeout()
+	case oserror.ErrPermission:
+		return checkErrMessageContent(e, "permission denied")
+	case oserror.ErrExist:
+		return checkErrMessageContent(e, "exists", "is a directory")
+	case oserror.ErrNotExist:
+		return checkErrMessageContent(e, "does not exist", "not found",
+			"has been removed", "no parent")
+	}
+	return false
+}
+
+// checkErrMessageContent checks if err message contains one of msgs.
+func checkErrMessageContent(e ErrorString, msgs ...string) bool {
+	for _, msg := range msgs {
+		if contains(string(e), msg) {
+			return true
+		}
+	}
+	return false
+}
+
+// contains is a local version of strings.Contains. It knows len(sep) > 1.
+func contains(s, sep string) bool {
+	n := len(sep)
+	c := sep[0]
+	for i := 0; i+n <= len(s); i++ {
+		if s[i] == c && s[i:i+n] == sep {
+			return true
+		}
+	}
+	return false
+}
+
 func (e ErrorString) Temporary() bool {
 	return e == EINTR || e == EMFILE || e.Timeout()
 }
diff --git a/src/syscall/syscall_unix.go b/src/syscall/syscall_unix.go
index 4336851554801..fd54dc0dc769e 100644
--- a/src/syscall/syscall_unix.go
+++ b/src/syscall/syscall_unix.go
@@ -7,6 +7,7 @@
 package syscall
 
 import (
+	"internal/oserror"
 	"internal/race"
 	"runtime"
 	"sync"
@@ -120,6 +121,22 @@ func (e Errno) Error() string {
 	return "errno " + itoa(int(e))
 }
 
+func (e Errno) Is(target error) bool {
+	switch target {
+	case oserror.ErrTemporary:
+		return e.Temporary()
+	case oserror.ErrTimeout:
+		return e.Timeout()
+	case oserror.ErrPermission:
+		return e == EACCES || e == EPERM
+	case oserror.ErrExist:
+		return e == EEXIST || e == ENOTEMPTY
+	case oserror.ErrNotExist:
+		return e == ENOENT
+	}
+	return false
+}
+
 func (e Errno) Temporary() bool {
 	return e == EINTR || e == EMFILE || e.Timeout()
 }
diff --git a/src/syscall/syscall_windows.go b/src/syscall/syscall_windows.go
index de05840386280..22c9e50a44178 100644
--- a/src/syscall/syscall_windows.go
+++ b/src/syscall/syscall_windows.go
@@ -8,6 +8,7 @@ package syscall
 
 import (
 	errorspkg "errors"
+	"internal/oserror"
 	"internal/race"
 	"runtime"
 	"sync"
@@ -110,6 +111,28 @@ func (e Errno) Error() string {
 	return string(utf16.Decode(b[:n]))
 }
 
+const _ERROR_BAD_NETPATH = Errno(53)
+
+func (e Errno) Is(target error) bool {
+	switch target {
+	case oserror.ErrTemporary:
+		return e.Temporary()
+	case oserror.ErrTimeout:
+		return e.Timeout()
+	case oserror.ErrPermission:
+		return e == ERROR_ACCESS_DENIED
+	case oserror.ErrExist:
+		return e == ERROR_ALREADY_EXISTS ||
+			e == ERROR_DIR_NOT_EMPTY ||
+			e == ERROR_FILE_EXISTS
+	case oserror.ErrNotExist:
+		return e == ERROR_FILE_NOT_FOUND ||
+			e == _ERROR_BAD_NETPATH ||
+			e == ERROR_PATH_NOT_FOUND
+	}
+	return false
+}
+
 func (e Errno) Temporary() bool {
 	return e == EINTR || e == EMFILE || e.Timeout()
 }