diff --git a/api/go1.15.txt b/api/go1.15.txt
index b51837cf3806c..dd90506eba46b 100644
--- a/api/go1.15.txt
+++ b/api/go1.15.txt
@@ -112,8 +112,6 @@ pkg debug/pe, const IMAGE_SUBSYSTEM_WINDOWS_GUI = 2
 pkg debug/pe, const IMAGE_SUBSYSTEM_WINDOWS_GUI ideal-int
 pkg debug/pe, const IMAGE_SUBSYSTEM_XBOX = 14
 pkg debug/pe, const IMAGE_SUBSYSTEM_XBOX ideal-int
-pkg go/printer, const StdFormat = 16
-pkg go/printer, const StdFormat Mode
 pkg math/big, method (*Int) FillBytes([]uint8) []uint8
 pkg net, method (*Resolver) LookupIP(context.Context, string, string) ([]IP, error)
 pkg net/url, method (*URL) EscapedFragment() string
diff --git a/doc/go1.15.html b/doc/go1.15.html
index e4a2491e7044b..448a507f6abae 100644
--- a/doc/go1.15.html
+++ b/doc/go1.15.html
@@ -658,15 +658,18 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
   </dd>
 </dl><!-- fmt -->
 
-<dl id="go/printer"><dt><a href="/pkg/go/printer/">go/printer</a></dt>
+<dl id="go/format"><dt><a href="/pkg/go/format/">go/format</a></dt>
   <dd>
-    <p><!-- CL 231461 -->
-      The new <a href="/pkg/go/printer/#Mode"><code>Mode</code></a>
-      value <a href="/pkg/go/printer/#StdFormat"><code>StdFormat</code></a>
-      directs the printer to apply standard formatting changes while
-      printing the output.
+    <p><!-- golang.org/issue/37476, CL 231461, CL 240683 -->
+      The <a href="/pkg/go/format/#Source"><code>Source</code></a> and
+      <a href="/pkg/go/format/#Node"><code>Node</code></a> functions
+      now canonicalize number literal prefixes and exponents as part
+      of formatting Go source code. This matches the behavior of the
+      <a href="/pkg/cmd/gofmt/"><code>gofmt</code></a> command as it
+      was implemented <a href="/doc/go1.13#gofmt">since Go 1.13</a>.
+    </p>
   </dd>
-</dl><!-- go/printer -->
+</dl><!-- go/format -->
 
 <dl id="html/template"><dt><a href="/pkg/html/template/">html/template</a></dt>
   <dd>
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index 679fdd7b8a531..8c56af7559690 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -40,7 +40,13 @@ var (
 // Keep these in sync with go/format/format.go.
 const (
 	tabWidth    = 8
-	printerMode = printer.UseSpaces | printer.TabIndent | printer.StdFormat
+	printerMode = printer.UseSpaces | printer.TabIndent | printerNormalizeNumbers
+
+	// printerNormalizeNumbers means to canonicalize number literal prefixes
+	// and exponents while printing. See https://golang.org/doc/go1.13#gofmt.
+	//
+	// This value is defined in go/printer specifically for go/format and cmd/gofmt.
+	printerNormalizeNumbers = 1 << 30
 )
 
 var (
diff --git a/src/go/format/format.go b/src/go/format/format.go
index 84afbb066a9c2..a603d9630e679 100644
--- a/src/go/format/format.go
+++ b/src/go/format/format.go
@@ -27,7 +27,13 @@ import (
 // Keep these in sync with cmd/gofmt/gofmt.go.
 const (
 	tabWidth    = 8
-	printerMode = printer.UseSpaces | printer.TabIndent | printer.StdFormat
+	printerMode = printer.UseSpaces | printer.TabIndent | printerNormalizeNumbers
+
+	// printerNormalizeNumbers means to canonicalize number literal prefixes
+	// and exponents while printing. See https://golang.org/doc/go1.13#gofmt.
+	//
+	// This value is defined in go/printer specifically for go/format and cmd/gofmt.
+	printerNormalizeNumbers = 1 << 30
 )
 
 var config = printer.Config{Mode: printerMode, Tabwidth: tabWidth}
diff --git a/src/go/format/format_test.go b/src/go/format/format_test.go
index aee51e2da13ac..58e088ede3153 100644
--- a/src/go/format/format_test.go
+++ b/src/go/format/format_test.go
@@ -58,8 +58,8 @@ func TestNode(t *testing.T) {
 	diff(t, buf.Bytes(), src)
 }
 
-// Node is documented to not modify the AST. Test that it is so, even when
-// formatting changes are applied due to printer.StdFormat mode being used.
+// Node is documented to not modify the AST.
+// Test that it is so even when numbers are normalized.
 func TestNodeNoModify(t *testing.T) {
 	const (
 		src    = "package p\n\nconst _ = 0000000123i\n"
diff --git a/src/go/printer/nodes.go b/src/go/printer/nodes.go
index 0360c4606e26d..95b9e918917cd 100644
--- a/src/go/printer/nodes.go
+++ b/src/go/printer/nodes.go
@@ -791,8 +791,8 @@ func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
 		}
 
 	case *ast.BasicLit:
-		if p.Config.Mode&StdFormat != 0 {
-			x = normalizeNumbers(x)
+		if p.Config.Mode&normalizeNumbers != 0 {
+			x = normalizedNumber(x)
 		}
 		p.print(x)
 
@@ -974,11 +974,15 @@ func (p *printer) expr1(expr ast.Expr, prec1, depth int) {
 	}
 }
 
-// normalizeNumbers rewrites base prefixes and exponents to
-// use lower-case letters, and removes leading 0's from
-// integer imaginary literals. It leaves hexadecimal digits
-// alone.
-func normalizeNumbers(lit *ast.BasicLit) *ast.BasicLit {
+// normalizedNumber rewrites base prefixes and exponents
+// of numbers to use lower-case letters (0X123 to 0x123 and 1.2E3 to 1.2e3),
+// and removes leading 0's from integer imaginary literals (0765i to 765i).
+// It leaves hexadecimal digits alone.
+//
+// normalizedNumber doesn't modify the ast.BasicLit value lit points to.
+// If lit is not a number or a number in canonical format already,
+// lit is returned as is. Otherwise a new ast.BasicLit is created.
+func normalizedNumber(lit *ast.BasicLit) *ast.BasicLit {
 	if lit.Kind != token.INT && lit.Kind != token.FLOAT && lit.Kind != token.IMAG {
 		return lit // not a number - nothing to do
 	}
diff --git a/src/go/printer/performance_test.go b/src/go/printer/performance_test.go
index 3f34bfcc326db..2e67154e6b4cf 100644
--- a/src/go/printer/performance_test.go
+++ b/src/go/printer/performance_test.go
@@ -20,7 +20,7 @@ import (
 var testfile *ast.File
 
 func testprint(out io.Writer, file *ast.File) {
-	if err := (&Config{TabIndent | UseSpaces | StdFormat, 8, 0}).Fprint(out, fset, file); err != nil {
+	if err := (&Config{TabIndent | UseSpaces | normalizeNumbers, 8, 0}).Fprint(out, fset, file); err != nil {
 		log.Fatalf("print error: %s", err)
 	}
 }
diff --git a/src/go/printer/printer.go b/src/go/printer/printer.go
index 9d0add40b6b97..0077afeaff7c9 100644
--- a/src/go/printer/printer.go
+++ b/src/go/printer/printer.go
@@ -1276,7 +1276,22 @@ const (
 	TabIndent                  // use tabs for indentation independent of UseSpaces
 	UseSpaces                  // use spaces instead of tabs for alignment
 	SourcePos                  // emit //line directives to preserve original source positions
-	StdFormat                  // apply standard formatting changes (exact byte output may change between versions of Go)
+)
+
+// The mode below is not included in printer's public API because
+// editing code text is deemed out of scope. Because this mode is
+// unexported, it's also possible to modify or remove it based on
+// the evolving needs of go/format and cmd/gofmt without breaking
+// users. See discussion in CL 240683.
+const (
+	// normalizeNumbers means to canonicalize number
+	// literal prefixes and exponents while printing.
+	//
+	// This value is known in and used by go/format and cmd/gofmt.
+	// It is currently more convenient and performant for those
+	// packages to apply number normalization during printing,
+	// rather than by modifying the AST in advance.
+	normalizeNumbers Mode = 1 << 30
 )
 
 // A Config node controls the output of Fprint.
diff --git a/src/go/printer/printer_test.go b/src/go/printer/printer_test.go
index 1e9d47ce73507..b64bc6bfb7d9a 100644
--- a/src/go/printer/printer_test.go
+++ b/src/go/printer/printer_test.go
@@ -33,7 +33,7 @@ type checkMode uint
 const (
 	export checkMode = 1 << iota
 	rawFormat
-	stdFormat
+	normNumber
 	idempotent
 )
 
@@ -58,8 +58,8 @@ func format(src []byte, mode checkMode) ([]byte, error) {
 	if mode&rawFormat != 0 {
 		cfg.Mode |= RawFormat
 	}
-	if mode&stdFormat != 0 {
-		cfg.Mode |= StdFormat
+	if mode&normNumber != 0 {
+		cfg.Mode |= normalizeNumbers
 	}
 
 	// print AST
@@ -205,7 +205,7 @@ var data = []entry{
 	{"slow.input", "slow.golden", idempotent},
 	{"complit.input", "complit.x", export},
 	{"go2numbers.input", "go2numbers.golden", idempotent},
-	{"go2numbers.input", "go2numbers.stdfmt", stdFormat | idempotent},
+	{"go2numbers.input", "go2numbers.norm", normNumber | idempotent},
 }
 
 func TestFiles(t *testing.T) {
diff --git a/src/go/printer/testdata/go2numbers.stdfmt b/src/go/printer/testdata/go2numbers.norm
similarity index 100%
rename from src/go/printer/testdata/go2numbers.stdfmt
rename to src/go/printer/testdata/go2numbers.norm