diff --git a/api/next.txt b/api/next.txt
index cb729ea72f..0a976d7b19 100644
--- a/api/next.txt
+++ b/api/next.txt
@@ -1,4 +1,8 @@
+pkg debug/buildinfo, func Read(io.ReaderAt) (*debug.BuildInfo, error)
+pkg debug/buildinfo, func ReadFile(string) (*debug.BuildInfo, error)
+pkg debug/buildinfo, type BuildInfo = debug.BuildInfo
 pkg runtime/debug, method (*BuildInfo) MarshalText() ([]byte, error)
+pkg runtime/debug, method (*BuildInfo) UnmarshalText() ([]byte, error)
 pkg syscall (darwin-amd64), func RecvfromInet4(int, []uint8, int, *SockaddrInet4) (int, error)
 pkg syscall (darwin-amd64), func RecvfromInet6(int, []uint8, int, *SockaddrInet6) (int, error)
 pkg syscall (darwin-amd64), func SendtoInet4(int, []uint8, int, SockaddrInet4) error
diff --git a/src/debug/buildinfo/buildinfo.go b/src/debug/buildinfo/buildinfo.go
new file mode 100644
index 0000000000..8def2eae6e
--- /dev/null
+++ b/src/debug/buildinfo/buildinfo.go
@@ -0,0 +1,374 @@
+// Copyright 2021 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 buildinfo provides access to information embedded in a Go binary
+// about how it was built. This includes the Go toolchain version, and the
+// set of modules used (for binaries built in module mode).
+//
+// Build information is available for the currently running binary in
+// runtime/debug.ReadBuildInfo.
+package buildinfo
+
+import (
+	"bytes"
+	"debug/elf"
+	"debug/macho"
+	"debug/pe"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"internal/xcoff"
+	"io"
+	"io/fs"
+	"os"
+	"runtime/debug"
+)
+
+// Type alias for build info. We cannot move the types here, since
+// runtime/debug would need to import this package, which would make it
+// a much larger dependency.
+type BuildInfo = debug.BuildInfo
+
+var (
+	// errUnrecognizedFormat is returned when a given executable file doesn't
+	// appear to be in a known format, or it breaks the rules of that format,
+	// or when there are I/O errors reading the file.
+	errUnrecognizedFormat = errors.New("unrecognized file format")
+
+	// errNotGoExe is returned when a given executable file is valid but does
+	// not contain Go build information.
+	errNotGoExe = errors.New("not a Go executable")
+
+	// The build info blob left by the linker is identified by
+	// a 16-byte header, consisting of buildInfoMagic (14 bytes),
+	// the binary's pointer size (1 byte),
+	// and whether the binary is big endian (1 byte).
+	buildInfoMagic = []byte("\xff Go buildinf:")
+)
+
+// ReadFile returns build information embedded in a Go binary
+// file at the given path. Most information is only available for binaries built
+// with module support.
+func ReadFile(name string) (info *BuildInfo, err error) {
+	defer func() {
+		if pathErr := (*fs.PathError)(nil); errors.As(err, &pathErr) {
+			err = fmt.Errorf("could not read Go build info: %w", err)
+		} else if err != nil {
+			err = fmt.Errorf("could not read Go build info from %s: %w", name, err)
+		}
+	}()
+
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return Read(f)
+}
+
+// Read returns build information embedded in a Go binary file
+// accessed through the given ReaderAt. Most information is only available for
+// binaries built with module support.
+func Read(r io.ReaderAt) (*BuildInfo, error) {
+	_, mod, err := readRawBuildInfo(r)
+	if err != nil {
+		return nil, err
+	}
+	bi := &BuildInfo{}
+	if err := bi.UnmarshalText([]byte(mod)); err != nil {
+		return nil, err
+	}
+	return bi, nil
+}
+
+type exe interface {
+	// ReadData reads and returns up to size bytes starting at virtual address addr.
+	ReadData(addr, size uint64) ([]byte, error)
+
+	// DataStart returns the virtual address of the segment or section that
+	// should contain build information. This is either a specially named section
+	// or the first writable non-zero data segment.
+	DataStart() uint64
+}
+
+// readRawBuildInfo extracts the Go toolchain version and module information
+// strings from a Go binary. On success, vers should be non-empty. mod
+// is empty if the binary was not built with modules enabled.
+func readRawBuildInfo(r io.ReaderAt) (vers, mod string, err error) {
+	// Read the first bytes of the file to identify the format, then delegate to
+	// a format-specific function to load segment and section headers.
+	ident := make([]byte, 16)
+	if n, err := r.ReadAt(ident, 0); n < len(ident) || err != nil {
+		return "", "", errUnrecognizedFormat
+	}
+
+	var x exe
+	switch {
+	case bytes.HasPrefix(ident, []byte("\x7FELF")):
+		f, err := elf.NewFile(r)
+		if err != nil {
+			return "", "", errUnrecognizedFormat
+		}
+		x = &elfExe{f}
+	case bytes.HasPrefix(ident, []byte("MZ")):
+		f, err := pe.NewFile(r)
+		if err != nil {
+			return "", "", errUnrecognizedFormat
+		}
+		x = &peExe{f}
+	case bytes.HasPrefix(ident, []byte("\xFE\xED\xFA")) || bytes.HasPrefix(ident[1:], []byte("\xFA\xED\xFE")):
+		f, err := macho.NewFile(r)
+		if err != nil {
+			return "", "", errUnrecognizedFormat
+		}
+		x = &machoExe{f}
+	case bytes.HasPrefix(ident, []byte{0x01, 0xDF}) || bytes.HasPrefix(ident, []byte{0x01, 0xF7}):
+		f, err := xcoff.NewFile(r)
+		if err != nil {
+			return "", "", errUnrecognizedFormat
+		}
+		x = &xcoffExe{f}
+	default:
+		return "", "", errUnrecognizedFormat
+	}
+
+	// Read the first 64kB of dataAddr to find the build info blob.
+	// On some platforms, the blob will be in its own section, and DataStart
+	// returns the address of that section. On others, it's somewhere in the
+	// data segment; the linker puts it near the beginning.
+	// See cmd/link/internal/ld.Link.buildinfo.
+	dataAddr := x.DataStart()
+	data, err := x.ReadData(dataAddr, 64*1024)
+	if err != nil {
+		return "", "", err
+	}
+	const (
+		buildInfoAlign = 16
+		buildinfoSize  = 32
+	)
+	for ; !bytes.HasPrefix(data, buildInfoMagic); data = data[buildInfoAlign:] {
+		if len(data) < 32 {
+			return "", "", errNotGoExe
+		}
+	}
+
+	// Decode the blob.
+	// The first 14 bytes are buildInfoMagic.
+	// The next two bytes indicate pointer size in bytes (4 or 8) and endianness
+	// (0 for little, 1 for big).
+	// Two virtual addresses to Go strings follow that: runtime.buildVersion,
+	// and runtime.modinfo.
+	// On 32-bit platforms, the last 8 bytes are unused.
+	ptrSize := int(data[14])
+	bigEndian := data[15] != 0
+	var bo binary.ByteOrder
+	if bigEndian {
+		bo = binary.BigEndian
+	} else {
+		bo = binary.LittleEndian
+	}
+	var readPtr func([]byte) uint64
+	if ptrSize == 4 {
+		readPtr = func(b []byte) uint64 { return uint64(bo.Uint32(b)) }
+	} else {
+		readPtr = bo.Uint64
+	}
+	vers = readString(x, ptrSize, readPtr, readPtr(data[16:]))
+	if vers == "" {
+		return "", "", errNotGoExe
+	}
+	mod = readString(x, ptrSize, readPtr, readPtr(data[16+ptrSize:]))
+	if len(mod) >= 33 && mod[len(mod)-17] == '\n' {
+		// Strip module framing: sentinel strings delimiting the module info.
+		// These are cmd/go/internal/modload.infoStart and infoEnd.
+		mod = mod[16 : len(mod)-16]
+	} else {
+		mod = ""
+	}
+
+	return vers, mod, nil
+}
+
+// readString returns the string at address addr in the executable x.
+func readString(x exe, ptrSize int, readPtr func([]byte) uint64, addr uint64) string {
+	hdr, err := x.ReadData(addr, uint64(2*ptrSize))
+	if err != nil || len(hdr) < 2*ptrSize {
+		return ""
+	}
+	dataAddr := readPtr(hdr)
+	dataLen := readPtr(hdr[ptrSize:])
+	data, err := x.ReadData(dataAddr, dataLen)
+	if err != nil || uint64(len(data)) < dataLen {
+		return ""
+	}
+	return string(data)
+}
+
+// elfExe is the ELF implementation of the exe interface.
+type elfExe struct {
+	f *elf.File
+}
+
+func (x *elfExe) ReadData(addr, size uint64) ([]byte, error) {
+	for _, prog := range x.f.Progs {
+		if prog.Vaddr <= addr && addr <= prog.Vaddr+prog.Filesz-1 {
+			n := prog.Vaddr + prog.Filesz - addr
+			if n > size {
+				n = size
+			}
+			data := make([]byte, n)
+			_, err := prog.ReadAt(data, int64(addr-prog.Vaddr))
+			if err != nil {
+				return nil, err
+			}
+			return data, nil
+		}
+	}
+	return nil, errUnrecognizedFormat
+}
+
+func (x *elfExe) DataStart() uint64 {
+	for _, s := range x.f.Sections {
+		if s.Name == ".go.buildinfo" {
+			return s.Addr
+		}
+	}
+	for _, p := range x.f.Progs {
+		if p.Type == elf.PT_LOAD && p.Flags&(elf.PF_X|elf.PF_W) == elf.PF_W {
+			return p.Vaddr
+		}
+	}
+	return 0
+}
+
+// peExe is the PE (Windows Portable Executable) implementation of the exe interface.
+type peExe struct {
+	f *pe.File
+}
+
+func (x *peExe) imageBase() uint64 {
+	switch oh := x.f.OptionalHeader.(type) {
+	case *pe.OptionalHeader32:
+		return uint64(oh.ImageBase)
+	case *pe.OptionalHeader64:
+		return oh.ImageBase
+	}
+	return 0
+}
+
+func (x *peExe) ReadData(addr, size uint64) ([]byte, error) {
+	addr -= x.imageBase()
+	for _, sect := range x.f.Sections {
+		if uint64(sect.VirtualAddress) <= addr && addr <= uint64(sect.VirtualAddress+sect.Size-1) {
+			n := uint64(sect.VirtualAddress+sect.Size) - addr
+			if n > size {
+				n = size
+			}
+			data := make([]byte, n)
+			_, err := sect.ReadAt(data, int64(addr-uint64(sect.VirtualAddress)))
+			if err != nil {
+				return nil, errUnrecognizedFormat
+			}
+			return data, nil
+		}
+	}
+	return nil, errUnrecognizedFormat
+}
+
+func (x *peExe) DataStart() uint64 {
+	// Assume data is first writable section.
+	const (
+		IMAGE_SCN_CNT_CODE               = 0x00000020
+		IMAGE_SCN_CNT_INITIALIZED_DATA   = 0x00000040
+		IMAGE_SCN_CNT_UNINITIALIZED_DATA = 0x00000080
+		IMAGE_SCN_MEM_EXECUTE            = 0x20000000
+		IMAGE_SCN_MEM_READ               = 0x40000000
+		IMAGE_SCN_MEM_WRITE              = 0x80000000
+		IMAGE_SCN_MEM_DISCARDABLE        = 0x2000000
+		IMAGE_SCN_LNK_NRELOC_OVFL        = 0x1000000
+		IMAGE_SCN_ALIGN_32BYTES          = 0x600000
+	)
+	for _, sect := range x.f.Sections {
+		if sect.VirtualAddress != 0 && sect.Size != 0 &&
+			sect.Characteristics&^IMAGE_SCN_ALIGN_32BYTES == IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_MEM_READ|IMAGE_SCN_MEM_WRITE {
+			return uint64(sect.VirtualAddress) + x.imageBase()
+		}
+	}
+	return 0
+}
+
+// machoExe is the Mach-O (Apple macOS/iOS) implementation of the exe interface.
+type machoExe struct {
+	f *macho.File
+}
+
+func (x *machoExe) ReadData(addr, size uint64) ([]byte, error) {
+	for _, load := range x.f.Loads {
+		seg, ok := load.(*macho.Segment)
+		if !ok {
+			continue
+		}
+		if seg.Addr <= addr && addr <= seg.Addr+seg.Filesz-1 {
+			if seg.Name == "__PAGEZERO" {
+				continue
+			}
+			n := seg.Addr + seg.Filesz - addr
+			if n > size {
+				n = size
+			}
+			data := make([]byte, n)
+			_, err := seg.ReadAt(data, int64(addr-seg.Addr))
+			if err != nil {
+				return nil, err
+			}
+			return data, nil
+		}
+	}
+	return nil, errUnrecognizedFormat
+}
+
+func (x *machoExe) DataStart() uint64 {
+	// Look for section named "__go_buildinfo".
+	for _, sec := range x.f.Sections {
+		if sec.Name == "__go_buildinfo" {
+			return sec.Addr
+		}
+	}
+	// Try the first non-empty writable segment.
+	const RW = 3
+	for _, load := range x.f.Loads {
+		seg, ok := load.(*macho.Segment)
+		if ok && seg.Addr != 0 && seg.Filesz != 0 && seg.Prot == RW && seg.Maxprot == RW {
+			return seg.Addr
+		}
+	}
+	return 0
+}
+
+// xcoffExe is the XCOFF (AIX eXtended COFF) implementation of the exe interface.
+type xcoffExe struct {
+	f *xcoff.File
+}
+
+func (x *xcoffExe) ReadData(addr, size uint64) ([]byte, error) {
+	for _, sect := range x.f.Sections {
+		if uint64(sect.VirtualAddress) <= addr && addr <= uint64(sect.VirtualAddress+sect.Size-1) {
+			n := uint64(sect.VirtualAddress+sect.Size) - addr
+			if n > size {
+				n = size
+			}
+			data := make([]byte, n)
+			_, err := sect.ReadAt(data, int64(addr-uint64(sect.VirtualAddress)))
+			if err != nil {
+				return nil, err
+			}
+			return data, nil
+		}
+	}
+	return nil, fmt.Errorf("address not mapped")
+}
+
+func (x *xcoffExe) DataStart() uint64 {
+	return x.f.SectionByType(xcoff.STYP_DATA).VirtualAddress
+}
diff --git a/src/debug/buildinfo/buildinfo_test.go b/src/debug/buildinfo/buildinfo_test.go
new file mode 100644
index 0000000000..765bf24627
--- /dev/null
+++ b/src/debug/buildinfo/buildinfo_test.go
@@ -0,0 +1,206 @@
+// Copyright 2021 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 buildinfo_test
+
+import (
+	"bytes"
+	"debug/buildinfo"
+	"flag"
+	"internal/testenv"
+	"os"
+	"os/exec"
+	"path"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+var flagAll = flag.Bool("all", false, "test all supported GOOS/GOARCH platforms, instead of only the current platform")
+
+// TestReadFile confirms that ReadFile can read build information from binaries
+// on supported target platforms. It builds a trivial binary on the current
+// platforms (or all platforms if -all is set) in various configurations and
+// checks that build information can or cannot be read.
+func TestReadFile(t *testing.T) {
+	if testing.Short() {
+		t.Skip("test requires compiling and linking, which may be slow")
+	}
+	testenv.MustHaveGoBuild(t)
+
+	type platform struct{ goos, goarch string }
+	platforms := []platform{
+		{"aix", "ppc64"},
+		{"darwin", "amd64"},
+		{"darwin", "arm64"},
+		{"linux", "386"},
+		{"linux", "amd64"},
+		{"windows", "386"},
+		{"windows", "amd64"},
+	}
+	runtimePlatform := platform{runtime.GOOS, runtime.GOARCH}
+	haveRuntimePlatform := false
+	for _, p := range platforms {
+		if p == runtimePlatform {
+			haveRuntimePlatform = true
+			break
+		}
+	}
+	if !haveRuntimePlatform {
+		platforms = append(platforms, runtimePlatform)
+	}
+
+	buildWithModules := func(t *testing.T, goos, goarch string) string {
+		dir := t.TempDir()
+		gomodPath := filepath.Join(dir, "go.mod")
+		gomodData := []byte("module example.com/m\ngo 1.18\n")
+		if err := os.WriteFile(gomodPath, gomodData, 0666); err != nil {
+			t.Fatal(err)
+		}
+		helloPath := filepath.Join(dir, "hello.go")
+		helloData := []byte("package main\nfunc main() {}\n")
+		if err := os.WriteFile(helloPath, helloData, 0666); err != nil {
+			t.Fatal(err)
+		}
+		outPath := filepath.Join(dir, path.Base(t.Name()))
+		cmd := exec.Command("go", "build", "-o="+outPath)
+		cmd.Dir = dir
+		cmd.Env = append(os.Environ(), "GO111MODULE=on", "GOOS="+goos, "GOARCH="+goarch)
+		stderr := &bytes.Buffer{}
+		cmd.Stderr = stderr
+		if err := cmd.Run(); err != nil {
+			t.Fatalf("failed building test file: %v\n%s", err, stderr.Bytes())
+		}
+		return outPath
+	}
+
+	buildWithGOPATH := func(t *testing.T, goos, goarch string) string {
+		gopathDir := t.TempDir()
+		pkgDir := filepath.Join(gopathDir, "src/example.com/m")
+		if err := os.MkdirAll(pkgDir, 0777); err != nil {
+			t.Fatal(err)
+		}
+		helloPath := filepath.Join(pkgDir, "hello.go")
+		helloData := []byte("package main\nfunc main() {}\n")
+		if err := os.WriteFile(helloPath, helloData, 0666); err != nil {
+			t.Fatal(err)
+		}
+		outPath := filepath.Join(gopathDir, path.Base(t.Name()))
+		cmd := exec.Command("go", "build", "-o="+outPath)
+		cmd.Dir = pkgDir
+		cmd.Env = append(os.Environ(), "GO111MODULE=off", "GOPATH="+gopathDir, "GOOS="+goos, "GOARCH="+goarch)
+		stderr := &bytes.Buffer{}
+		cmd.Stderr = stderr
+		if err := cmd.Run(); err != nil {
+			t.Fatalf("failed building test file: %v\n%s", err, stderr.Bytes())
+		}
+		return outPath
+	}
+
+	damageBuildInfo := func(t *testing.T, name string) {
+		data, err := os.ReadFile(name)
+		if err != nil {
+			t.Fatal(err)
+		}
+		i := bytes.Index(data, []byte("\xff Go buildinf:"))
+		if i < 0 {
+			t.Fatal("Go buildinf not found")
+		}
+		data[i+2] = 'N'
+		if err := os.WriteFile(name, data, 0666); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	cases := []struct {
+		name    string
+		build   func(t *testing.T, goos, goarch string) string
+		want    string
+		wantErr string
+	}{
+		{
+			name: "doesnotexist",
+			build: func(t *testing.T, goos, goarch string) string {
+				return "doesnotexist.txt"
+			},
+			wantErr: "doesnotexist",
+		},
+		{
+			name: "empty",
+			build: func(t *testing.T, _, _ string) string {
+				dir := t.TempDir()
+				name := filepath.Join(dir, "empty")
+				if err := os.WriteFile(name, nil, 0666); err != nil {
+					t.Fatal(err)
+				}
+				return name
+			},
+			wantErr: "unrecognized file format",
+		},
+		{
+			name:  "valid_modules",
+			build: buildWithModules,
+			want: "path\texample.com/m\n" +
+				"mod\texample.com/m\t(devel)\t\n",
+		},
+		{
+			name: "invalid_modules",
+			build: func(t *testing.T, goos, goarch string) string {
+				name := buildWithModules(t, goos, goarch)
+				damageBuildInfo(t, name)
+				return name
+			},
+			wantErr: "not a Go executable",
+		},
+		{
+			name:  "valid_gopath",
+			build: buildWithGOPATH,
+			want:  "",
+		},
+		{
+			name: "invalid_gopath",
+			build: func(t *testing.T, goos, goarch string) string {
+				name := buildWithGOPATH(t, goos, goarch)
+				damageBuildInfo(t, name)
+				return name
+			},
+			wantErr: "not a Go executable",
+		},
+	}
+
+	for _, p := range platforms {
+		p := p
+		t.Run(p.goos+"_"+p.goarch, func(t *testing.T) {
+			if p != runtimePlatform && !*flagAll {
+				t.Skipf("skipping platforms other than %s_%s because -all was not set", runtimePlatform.goos, runtimePlatform.goarch)
+			}
+			for _, tc := range cases {
+				tc := tc
+				t.Run(tc.name, func(t *testing.T) {
+					t.Parallel()
+					name := tc.build(t, p.goos, p.goarch)
+					if info, err := buildinfo.ReadFile(name); err != nil {
+						if tc.wantErr == "" {
+							t.Fatalf("unexpected error: %v", err)
+						} else if errMsg := err.Error(); !strings.Contains(errMsg, tc.wantErr) {
+							t.Fatalf("got error %q; want error containing %q", errMsg, tc.wantErr)
+						}
+					} else {
+						if tc.wantErr != "" {
+							t.Fatalf("unexpected success; want error containing %q", tc.wantErr)
+						} else if got, err := info.MarshalText(); err != nil {
+							t.Fatalf("unexpected error marshaling BuildInfo: %v", err)
+						} else {
+							got := string(got)
+							if got != tc.want {
+								t.Fatalf("got:\n%s\nwant:\n%s", got, tc.want)
+							}
+						}
+					}
+				})
+			}
+		})
+	}
+}
diff --git a/src/go/build/deps_test.go b/src/go/build/deps_test.go
index 07fbc8b023..a92bb3893b 100644
--- a/src/go/build/deps_test.go
+++ b/src/go/build/deps_test.go
@@ -214,7 +214,6 @@ var depsRules = `
 	  mime/quotedprintable,
 	  net/internal/socktest,
 	  net/url,
-	  runtime/debug,
 	  runtime/trace,
 	  text/scanner,
 	  text/tabwriter;
@@ -271,8 +270,10 @@ var depsRules = `
 
 	# executable parsing
 	FMT, encoding/binary, compress/zlib
+	< runtime/debug
 	< debug/dwarf
 	< debug/elf, debug/gosym, debug/macho, debug/pe, debug/plan9obj, internal/xcoff
+	< debug/buildinfo
 	< DEBUG;
 
 	# go parser and friends.
@@ -510,7 +511,7 @@ var depsRules = `
 	FMT, flag, math/rand
 	< testing/quick;
 
-	FMT, flag, runtime/debug, runtime/trace, internal/sysinfo, math/rand
+	FMT, DEBUG, flag, runtime/trace, internal/sysinfo, math/rand
 	< testing;
 
 	FMT, crypto/sha256, encoding/json, go/ast, go/parser, go/token, math/rand, encoding/hex, crypto/sha256
diff --git a/src/runtime/debug/mod.go b/src/runtime/debug/mod.go
index 11f995ba75..8c6c48089b 100644
--- a/src/runtime/debug/mod.go
+++ b/src/runtime/debug/mod.go
@@ -7,7 +7,6 @@ package debug
 import (
 	"bytes"
 	"fmt"
-	"strings"
 )
 
 // exported from runtime
@@ -17,11 +16,19 @@ func modinfo() string
 // in the running binary. The information is available only
 // in binaries built with module support.
 func ReadBuildInfo() (info *BuildInfo, ok bool) {
-	return readBuildInfo(modinfo())
+	data := modinfo()
+	if len(data) < 32 {
+		return nil, false
+	}
+	data = data[16 : len(data)-16]
+	bi := &BuildInfo{}
+	if err := bi.UnmarshalText([]byte(data)); err != nil {
+		return nil, false
+	}
+	return bi, true
 }
 
-// BuildInfo represents the build information read from
-// the running binary.
+// BuildInfo represents the build information read from a Go binary.
 type BuildInfo struct {
 	Path string    // The main package path
 	Main Module    // The module containing the main package
@@ -71,80 +78,85 @@ func (bi *BuildInfo) MarshalText() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
-func readBuildInfo(data string) (*BuildInfo, bool) {
-	if len(data) < 32 {
-		return nil, false
-	}
-	data = data[16 : len(data)-16]
+func (bi *BuildInfo) UnmarshalText(data []byte) (err error) {
+	*bi = BuildInfo{}
+	lineNum := 1
+	defer func() {
+		if err != nil {
+			err = fmt.Errorf("could not parse Go build info: line %d: %w", lineNum, err)
+		}
+	}()
 
-	const (
-		pathLine = "path\t"
-		modLine  = "mod\t"
-		depLine  = "dep\t"
-		repLine  = "=>\t"
+	var (
+		pathLine = []byte("path\t")
+		modLine  = []byte("mod\t")
+		depLine  = []byte("dep\t")
+		repLine  = []byte("=>\t")
+		newline  = []byte("\n")
+		tab      = []byte("\t")
 	)
 
-	readEntryFirstLine := func(elem []string) (Module, bool) {
+	readModuleLine := func(elem [][]byte) (Module, error) {
 		if len(elem) != 2 && len(elem) != 3 {
-			return Module{}, false
+			return Module{}, fmt.Errorf("expected 2 or 3 columns; got %d", len(elem))
 		}
 		sum := ""
 		if len(elem) == 3 {
-			sum = elem[2]
+			sum = string(elem[2])
 		}
 		return Module{
-			Path:    elem[0],
-			Version: elem[1],
+			Path:    string(elem[0]),
+			Version: string(elem[1]),
 			Sum:     sum,
-		}, true
+		}, nil
 	}
 
 	var (
-		info = &BuildInfo{}
 		last *Module
-		line string
+		line []byte
 		ok   bool
 	)
-	// Reverse of cmd/go/internal/modload.PackageBuildInfo
+	// Reverse of BuildInfo.String()
 	for len(data) > 0 {
-		line, data, ok = strings.Cut(data, "\n")
+		line, data, ok = bytes.Cut(data, newline)
 		if !ok {
 			break
 		}
 		switch {
-		case strings.HasPrefix(line, pathLine):
+		case bytes.HasPrefix(line, pathLine):
 			elem := line[len(pathLine):]
-			info.Path = elem
-		case strings.HasPrefix(line, modLine):
-			elem := strings.Split(line[len(modLine):], "\t")
-			last = &info.Main
-			*last, ok = readEntryFirstLine(elem)
-			if !ok {
-				return nil, false
+			bi.Path = string(elem)
+		case bytes.HasPrefix(line, modLine):
+			elem := bytes.Split(line[len(modLine):], tab)
+			last = &bi.Main
+			*last, err = readModuleLine(elem)
+			if err != nil {
+				return err
 			}
-		case strings.HasPrefix(line, depLine):
-			elem := strings.Split(line[len(depLine):], "\t")
+		case bytes.HasPrefix(line, depLine):
+			elem := bytes.Split(line[len(depLine):], tab)
 			last = new(Module)
-			info.Deps = append(info.Deps, last)
-			*last, ok = readEntryFirstLine(elem)
-			if !ok {
-				return nil, false
+			bi.Deps = append(bi.Deps, last)
+			*last, err = readModuleLine(elem)
+			if err != nil {
+				return err
 			}
-		case strings.HasPrefix(line, repLine):
-			elem := strings.Split(line[len(repLine):], "\t")
+		case bytes.HasPrefix(line, repLine):
+			elem := bytes.Split(line[len(repLine):], tab)
 			if len(elem) != 3 {
-				return nil, false
+				return fmt.Errorf("expected 3 columns for replacement; got %d", len(elem))
 			}
 			if last == nil {
-				return nil, false
+				return fmt.Errorf("replacement with no module on previous line")
 			}
 			last.Replace = &Module{
-				Path:    elem[0],
-				Version: elem[1],
-				Sum:     elem[2],
+				Path:    string(elem[0]),
+				Version: string(elem[1]),
+				Sum:     string(elem[2]),
 			}
 			last = nil
 		}
+		lineNum++
 	}
-	return info, true
+	return nil
 }