diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index 999fcf7e53..9d4626769d 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -841,6 +841,7 @@
 //         UseAllFiles   bool     // use files regardless of +build lines, file names
 //         Compiler      string   // compiler to assume when computing target paths
 //         BuildTags     []string // build constraints to match in +build lines
+//         ToolTags      []string // toolchain-specific build constraints
 //         ReleaseTags   []string // releases the current release is compatible with
 //         InstallSuffix string   // suffix to use in the name of the install dir
 //     }
diff --git a/src/cmd/go/internal/list/context.go b/src/cmd/go/internal/list/context.go
index 68d691ebe2..2dc63766b7 100644
--- a/src/cmd/go/internal/list/context.go
+++ b/src/cmd/go/internal/list/context.go
@@ -17,6 +17,7 @@ type Context struct {
 	UseAllFiles   bool     `json:",omitempty"` // use files regardless of +build lines, file names
 	Compiler      string   `json:",omitempty"` // compiler to assume when computing target paths
 	BuildTags     []string `json:",omitempty"` // build constraints to match in +build lines
+	ToolTags      []string `json:",omitempty"` // toolchain-specific build constraints
 	ReleaseTags   []string `json:",omitempty"` // releases the current release is compatible with
 	InstallSuffix string   `json:",omitempty"` // suffix to use in the name of the install dir
 }
@@ -31,6 +32,7 @@ func newContext(c *build.Context) *Context {
 		UseAllFiles:   c.UseAllFiles,
 		Compiler:      c.Compiler,
 		BuildTags:     c.BuildTags,
+		ToolTags:      c.ToolTags,
 		ReleaseTags:   c.ReleaseTags,
 		InstallSuffix: c.InstallSuffix,
 	}
diff --git a/src/cmd/go/internal/list/list.go b/src/cmd/go/internal/list/list.go
index 221370bd19..53bf75e27e 100644
--- a/src/cmd/go/internal/list/list.go
+++ b/src/cmd/go/internal/list/list.go
@@ -148,6 +148,7 @@ The template function "context" returns the build context, defined as:
         UseAllFiles   bool     // use files regardless of +build lines, file names
         Compiler      string   // compiler to assume when computing target paths
         BuildTags     []string // build constraints to match in +build lines
+        ToolTags      []string // toolchain-specific build constraints
         ReleaseTags   []string // releases the current release is compatible with
         InstallSuffix string   // suffix to use in the name of the install dir
     }
diff --git a/src/cmd/go/internal/work/init.go b/src/cmd/go/internal/work/init.go
index 66e1ca7d80..ca7e04d280 100644
--- a/src/cmd/go/internal/work/init.go
+++ b/src/cmd/go/internal/work/init.go
@@ -14,7 +14,6 @@ import (
 	"cmd/internal/sys"
 	"flag"
 	"fmt"
-	"internal/buildcfg"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -46,15 +45,6 @@ func BuildInit() {
 			base.Fatalf("go %s: %s environment variable is relative; must be absolute path: %s\n", flag.Args()[0], key, path)
 		}
 	}
-
-	// For each experiment that has been enabled in the toolchain, define a
-	// build tag with the same name but prefixed by "goexperiment." which can be
-	// used for compiling alternative files for the experiment. This allows
-	// changes for the experiment, like extra struct fields in the runtime,
-	// without affecting the base non-experiment code at all.
-	for _, expt := range buildcfg.EnabledExperiments() {
-		cfg.BuildContext.BuildTags = append(cfg.BuildContext.BuildTags, "goexperiment."+expt)
-	}
 }
 
 func instrumentInit() {
diff --git a/src/go/build/build.go b/src/go/build/build.go
index 501ce2e8dd..8d1a107c6e 100644
--- a/src/go/build/build.go
+++ b/src/go/build/build.go
@@ -12,6 +12,7 @@ import (
 	"go/build/constraint"
 	"go/doc"
 	"go/token"
+	"internal/buildcfg"
 	exec "internal/execabs"
 	"internal/goroot"
 	"internal/goversion"
@@ -48,16 +49,18 @@ type Context struct {
 	UseAllFiles bool   // use files regardless of +build lines, file names
 	Compiler    string // compiler to assume when computing target paths
 
-	// The build and release tags specify build constraints
+	// The build, tool, and release tags specify build constraints
 	// that should be considered satisfied when processing +build lines.
 	// Clients creating a new context may customize BuildTags, which
-	// defaults to empty, but it is usually an error to customize ReleaseTags,
-	// which defaults to the list of Go releases the current release is compatible with.
+	// defaults to empty, but it is usually an error to customize ToolTags or ReleaseTags.
+	// ToolTags defaults to build tags appropriate to the current Go toolchain configuration.
+	// ReleaseTags defaults to the list of Go releases the current release is compatible with.
 	// BuildTags is not set for the Default build Context.
-	// In addition to the BuildTags and ReleaseTags, build constraints
+	// In addition to the BuildTags, ToolTags, and ReleaseTags, build constraints
 	// consider the values of GOARCH and GOOS as satisfied tags.
 	// The last element in ReleaseTags is assumed to be the current release.
 	BuildTags   []string
+	ToolTags    []string
 	ReleaseTags []string
 
 	// The install suffix specifies a suffix to use in the name of the installation
@@ -292,17 +295,27 @@ func defaultGOPATH() string {
 	return ""
 }
 
-var defaultReleaseTags []string
+var defaultToolTags, defaultReleaseTags []string
 
 func defaultContext() Context {
 	var c Context
 
-	c.GOARCH = envOr("GOARCH", runtime.GOARCH)
-	c.GOOS = envOr("GOOS", runtime.GOOS)
+	c.GOARCH = buildcfg.GOARCH
+	c.GOOS = buildcfg.GOOS
 	c.GOROOT = pathpkg.Clean(runtime.GOROOT())
 	c.GOPATH = envOr("GOPATH", defaultGOPATH())
 	c.Compiler = runtime.Compiler
 
+	// For each experiment that has been enabled in the toolchain, define a
+	// build tag with the same name but prefixed by "goexperiment." which can be
+	// used for compiling alternative files for the experiment. This allows
+	// changes for the experiment, like extra struct fields in the runtime,
+	// without affecting the base non-experiment code at all.
+	for _, exp := range buildcfg.EnabledExperiments() {
+		c.ToolTags = append(c.ToolTags, "goexperiment."+exp)
+	}
+	defaultToolTags = append([]string{}, c.ToolTags...) // our own private copy
+
 	// Each major Go release in the Go 1.x series adds a new
 	// "go1.x" release tag. That is, the go1.x tag is present in
 	// all releases >= Go 1.x. Code that requires Go 1.x or later
@@ -1056,7 +1069,7 @@ func (ctxt *Context) importGo(p *Package, path, srcDir string, mode ImportMode)
 	// we must not being doing special things like AllowBinary or IgnoreVendor,
 	// and all the file system callbacks must be nil (we're meant to use the local file system).
 	if mode&AllowBinary != 0 || mode&IgnoreVendor != 0 ||
-		ctxt.JoinPath != nil || ctxt.SplitPathList != nil || ctxt.IsAbsPath != nil || ctxt.IsDir != nil || ctxt.HasSubdir != nil || ctxt.ReadDir != nil || ctxt.OpenFile != nil || !equal(ctxt.ReleaseTags, defaultReleaseTags) {
+		ctxt.JoinPath != nil || ctxt.SplitPathList != nil || ctxt.IsAbsPath != nil || ctxt.IsDir != nil || ctxt.HasSubdir != nil || ctxt.ReadDir != nil || ctxt.OpenFile != nil || !equal(ctxt.ToolTags, defaultToolTags) || !equal(ctxt.ReleaseTags, defaultReleaseTags) {
 		return errNoModules
 	}
 
@@ -1892,6 +1905,11 @@ func (ctxt *Context) matchTag(name string, allTags map[string]bool) bool {
 			return true
 		}
 	}
+	for _, tag := range ctxt.ToolTags {
+		if tag == name {
+			return true
+		}
+	}
 	for _, tag := range ctxt.ReleaseTags {
 		if tag == name {
 			return true
diff --git a/test/run.go b/test/run.go
index feec2b50be..5e60de7624 100644
--- a/test/run.go
+++ b/test/run.go
@@ -12,6 +12,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"go/build"
 	"hash/fnv"
 	"io"
 	"io/fs"
@@ -376,7 +377,6 @@ type context struct {
 	GOARCH     string
 	cgoEnabled bool
 	noOptEnv   bool
-	expTags    map[string]bool // Set lazily
 }
 
 // shouldTest looks for build tags in a source file and returns
@@ -447,27 +447,12 @@ func (ctxt *context) match(name string) bool {
 	}
 
 	if strings.HasPrefix(name, "goexperiment.") {
-		// Query goexperiment tags from the toolchain.
-		if ctxt.expTags == nil {
-			ctxt.expTags = make(map[string]bool)
-			cmd := exec.Command(goTool(), "tool", "compile", "-V=goexperiment")
-			out, err := cmd.CombinedOutput()
-			if err != nil {
-				log.Fatalf("failed to get GOEXPERIMENT configuration:\n%s", out)
-			}
-			i := bytes.Index(out, []byte("X:"))
-			if i != -1 {
-				for _, exp := range strings.Split(string(out[i+2:]), ",") {
-					v := true
-					if strings.HasPrefix(exp, "no") {
-						v, exp = false, exp[2:]
-					}
-					ctxt.expTags["goexperiment."+exp] = v
-				}
+		for _, tag := range build.Default.ToolTags {
+			if tag == name {
+				return true
 			}
 		}
-
-		return ctxt.expTags[name]
+		return false
 	}
 
 	if name == "cgo" && ctxt.cgoEnabled {