diff --git a/src/cmd/compile/internal/syntax/nodes.go b/src/cmd/compile/internal/syntax/nodes.go
index e943a9a9e6..6580f053c7 100644
--- a/src/cmd/compile/internal/syntax/nodes.go
+++ b/src/cmd/compile/internal/syntax/nodes.go
@@ -34,10 +34,11 @@ func (*node) aNode()     {}
 
 // package PkgName; DeclList[0], DeclList[1], ...
 type File struct {
-	Pragma   Pragma
-	PkgName  *Name
-	DeclList []Decl
-	EOF      Pos
+	Pragma    Pragma
+	PkgName   *Name
+	DeclList  []Decl
+	EOF       Pos
+	GoVersion string
 	node
 }
 
diff --git a/src/cmd/compile/internal/syntax/parser.go b/src/cmd/compile/internal/syntax/parser.go
index ee9761e4a6..c8b8ab0601 100644
--- a/src/cmd/compile/internal/syntax/parser.go
+++ b/src/cmd/compile/internal/syntax/parser.go
@@ -6,6 +6,7 @@ package syntax
 
 import (
 	"fmt"
+	"go/build/constraint"
 	"io"
 	"strconv"
 	"strings"
@@ -21,17 +22,20 @@ type parser struct {
 	pragh PragmaHandler
 	scanner
 
-	base   *PosBase // current position base
-	first  error    // first error encountered
-	errcnt int      // number of errors encountered
-	pragma Pragma   // pragmas
+	base      *PosBase // current position base
+	first     error    // first error encountered
+	errcnt    int      // number of errors encountered
+	pragma    Pragma   // pragmas
+	goVersion string   // Go version from //go:build line
 
+	top    bool   // in top of file (before package clause)
 	fnest  int    // function nesting level (for error handling)
 	xnest  int    // expression nesting level (for complit ambiguity resolution)
 	indent []byte // tracing support
 }
 
 func (p *parser) init(file *PosBase, r io.Reader, errh ErrorHandler, pragh PragmaHandler, mode Mode) {
+	p.top = true
 	p.file = file
 	p.errh = errh
 	p.mode = mode
@@ -70,8 +74,15 @@ func (p *parser) init(file *PosBase, r io.Reader, errh ErrorHandler, pragh Pragm
 			}
 
 			// go: directive (but be conservative and test)
-			if pragh != nil && strings.HasPrefix(text, "go:") {
-				p.pragma = pragh(p.posAt(line, col+2), p.scanner.blank, text, p.pragma) // +2 to skip over // or /*
+			if strings.HasPrefix(text, "go:") {
+				if p.top && strings.HasPrefix(msg, "//go:build") {
+					if x, err := constraint.Parse(msg); err == nil {
+						p.goVersion = constraint.GoVersion(x)
+					}
+				}
+				if pragh != nil {
+					p.pragma = pragh(p.posAt(line, col+2), p.scanner.blank, text, p.pragma) // +2 to skip over // or /*
+				}
 			}
 		},
 		directives,
@@ -388,6 +399,8 @@ func (p *parser) fileOrNil() *File {
 	f.pos = p.pos()
 
 	// PackageClause
+	f.GoVersion = p.goVersion
+	p.top = false
 	if !p.got(_Package) {
 		p.syntaxError("package statement must be first")
 		return nil
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index a287eeda67..306d039034 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -263,13 +263,15 @@ var depsRules = `
 	< go/token
 	< go/scanner
 	< go/ast
-	< go/internal/typeparams
-	< go/parser;
+	< go/internal/typeparams;
 
 	FMT
 	< go/build/constraint, go/doc/comment;
 
-	go/build/constraint, go/doc/comment, go/parser, text/tabwriter
+	go/internal/typeparams, go/build/constraint
+	< go/parser;
+
+	go/doc/comment, go/parser, text/tabwriter
 	< go/printer
 	< go/format;
 
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index dec0245261..e1d941eff3 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -18,9 +18,11 @@ package parser
 import (
 	"fmt"
 	"go/ast"
+	"go/build/constraint"
 	"go/internal/typeparams"
 	"go/scanner"
 	"go/token"
+	"strings"
 )
 
 // The parser structure holds the parser's internal state.
@@ -38,6 +40,8 @@ type parser struct {
 	comments    []*ast.CommentGroup
 	leadComment *ast.CommentGroup // last lead comment
 	lineComment *ast.CommentGroup // last line comment
+	top         bool              // in top of file (before package clause)
+	goVersion   string            // minimum Go version found in //go:build comment
 
 	// Next token
 	pos token.Pos   // token position
@@ -64,13 +68,10 @@ type parser struct {
 
 func (p *parser) init(fset *token.FileSet, filename string, src []byte, mode Mode) {
 	p.file = fset.AddFile(filename, -1, len(src))
-	var m scanner.Mode
-	if mode&ParseComments != 0 {
-		m = scanner.ScanComments
-	}
 	eh := func(pos token.Position, msg string) { p.errors.Add(pos, msg) }
-	p.scanner.Init(p.file, src, eh, m)
+	p.scanner.Init(p.file, src, eh, scanner.ScanComments)
 
+	p.top = true
 	p.mode = mode
 	p.trace = mode&Trace != 0 // for convenience (p.trace is used frequently)
 	p.next()
@@ -142,7 +143,23 @@ func (p *parser) next0() {
 		}
 	}
 
-	p.pos, p.tok, p.lit = p.scanner.Scan()
+	for {
+		p.pos, p.tok, p.lit = p.scanner.Scan()
+		if p.tok == token.COMMENT {
+			if p.top && strings.HasPrefix(p.lit, "//go:build") {
+				if x, err := constraint.Parse(p.lit); err == nil {
+					p.goVersion = constraint.GoVersion(x)
+				}
+			}
+			if p.mode&ParseComments == 0 {
+				continue
+			}
+		} else {
+			// Found a non-comment; top of file is over.
+			p.top = false
+		}
+		break
+	}
 }
 
 // Consume a comment and return it and the line on which it ends.
@@ -2851,6 +2868,7 @@ func (p *parser) parseFile() *ast.File {
 		FileEnd:   token.Pos(p.file.Base() + p.file.Size()),
 		Imports:   p.imports,
 		Comments:  p.comments,
+		GoVersion: p.goVersion,
 	}
 	var declErr func(token.Pos, string)
 	if p.mode&DeclarationErrors != 0 {
diff --git a/src/go/parser/parser_test.go b/src/go/parser/parser_test.go
index 22b11a0cc4..65c8520b49 100644
--- a/src/go/parser/parser_test.go
+++ b/src/go/parser/parser_test.go
@@ -780,3 +780,23 @@ func TestIssue59180(t *testing.T) {
 		}
 	}
 }
+
+func TestGoVersion(t *testing.T) {
+	fset := token.NewFileSet()
+	pkgs, err := ParseDir(fset, "./testdata/goversion", nil, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, p := range pkgs {
+		want := strings.ReplaceAll(p.Name, "_", ".")
+		if want == "none" {
+			want = ""
+		}
+		for _, f := range p.Files {
+			if f.GoVersion != want {
+				t.Errorf("%s: GoVersion = %q, want %q", fset.Position(f.Pos()), f.GoVersion, want)
+			}
+		}
+	}
+}
diff --git a/src/go/parser/testdata/goversion/t01.go b/src/go/parser/testdata/goversion/t01.go
new file mode 100644
index 0000000000..5cfa0ccc00
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t01.go
@@ -0,0 +1,3 @@
+//go:build windows
+
+package none
diff --git a/src/go/parser/testdata/goversion/t02.go b/src/go/parser/testdata/goversion/t02.go
new file mode 100644
index 0000000000..d91f995875
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t02.go
@@ -0,0 +1,3 @@
+//go:build linux && go1.2
+
+package go1_2
diff --git a/src/go/parser/testdata/goversion/t03.go b/src/go/parser/testdata/goversion/t03.go
new file mode 100644
index 0000000000..97fc9ae3af
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t03.go
@@ -0,0 +1,3 @@
+//go:build linux && go1.2 || windows
+
+package none
diff --git a/src/go/parser/testdata/goversion/t04.go b/src/go/parser/testdata/goversion/t04.go
new file mode 100644
index 0000000000..e81f9c0383
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t04.go
@@ -0,0 +1,5 @@
+// copyright notice
+
+//go:build (linux && go1.2) || (windows && go1.1)
+
+package go1_1
diff --git a/src/go/parser/testdata/goversion/t05.go b/src/go/parser/testdata/goversion/t05.go
new file mode 100644
index 0000000000..42c6b33d83
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t05.go
@@ -0,0 +1,3 @@
+//go:build linux && go1.2 && go1.4
+
+package go1_4
diff --git a/src/go/parser/testdata/goversion/t06.go b/src/go/parser/testdata/goversion/t06.go
new file mode 100644
index 0000000000..22944de944
--- /dev/null
+++ b/src/go/parser/testdata/goversion/t06.go
@@ -0,0 +1,3 @@
+//go:build go1
+
+package go1