diff --git a/src/cmd/compile/internal/x86/galign.go b/src/cmd/compile/internal/x86/galign.go
index 2d20b6a6d0..e137daa3fc 100644
--- a/src/cmd/compile/internal/x86/galign.go
+++ b/src/cmd/compile/internal/x86/galign.go
@@ -7,6 +7,9 @@ package x86
 import (
 	"cmd/compile/internal/gc"
 	"cmd/internal/obj/x86"
+	"cmd/internal/objabi"
+	"fmt"
+	"os"
 )
 
 func Init(arch *gc.Arch) {
@@ -15,6 +18,18 @@ func Init(arch *gc.Arch) {
 	arch.SSAGenValue = ssaGenValue
 	arch.SSAGenBlock = ssaGenBlock
 	arch.MAXWIDTH = (1 << 32) - 1
+	switch v := objabi.GO386; v {
+	case "sse2":
+	case "softfloat":
+		arch.SoftFloat = true
+	case "387":
+		fmt.Fprintf(os.Stderr, "unsupported setting GO386=387. Consider using GO386=softfloat instead.\n")
+		gc.Exit(1)
+	default:
+		fmt.Fprintf(os.Stderr, "unsupported setting GO386=%s\n", v)
+		gc.Exit(1)
+
+	}
 
 	arch.ZeroRange = zerorange
 	arch.Ginsnop = ginsnop
diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 3b3eb113b1..69a66abd2d 100644
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -30,6 +30,7 @@ var (
 	gohostos         string
 	goos             string
 	goarm            string
+	go386            string
 	gomips           string
 	gomips64         string
 	goppc64          string
@@ -141,6 +142,12 @@ func xinit() {
 	}
 	goarm = b
 
+	b = os.Getenv("GO386")
+	if b == "" {
+		b = "sse2"
+	}
+	go386 = b
+
 	b = os.Getenv("GOMIPS")
 	if b == "" {
 		b = "hardfloat"
@@ -212,6 +219,7 @@ func xinit() {
 	defaultldso = os.Getenv("GO_LDSO")
 
 	// For tools being invoked but also for os.ExpandEnv.
+	os.Setenv("GO386", go386)
 	os.Setenv("GOARCH", goarch)
 	os.Setenv("GOARM", goarm)
 	os.Setenv("GOHOSTARCH", gohostarch)
@@ -1153,6 +1161,9 @@ func cmdenv() {
 	if goarch == "arm" {
 		xprintf(format, "GOARM", goarm)
 	}
+	if goarch == "386" {
+		xprintf(format, "GO386", go386)
+	}
 	if goarch == "mips" || goarch == "mipsle" {
 		xprintf(format, "GOMIPS", gomips)
 	}
diff --git a/src/cmd/dist/buildruntime.go b/src/cmd/dist/buildruntime.go
index 67d1d72db4..2744951597 100644
--- a/src/cmd/dist/buildruntime.go
+++ b/src/cmd/dist/buildruntime.go
@@ -41,6 +41,7 @@ func mkzversion(dir, file string) {
 //	package objabi
 //
 //	const defaultGOROOT = <goroot>
+//	const defaultGO386 = <go386>
 //	const defaultGOARM = <goarm>
 //	const defaultGOMIPS = <gomips>
 //	const defaultGOMIPS64 = <gomips64>
@@ -69,6 +70,7 @@ func mkzbootstrap(file string) {
 	fmt.Fprintln(&buf)
 	fmt.Fprintf(&buf, "import \"runtime\"\n")
 	fmt.Fprintln(&buf)
+	fmt.Fprintf(&buf, "const defaultGO386 = `%s`\n", go386)
 	fmt.Fprintf(&buf, "const defaultGOARM = `%s`\n", goarm)
 	fmt.Fprintf(&buf, "const defaultGOMIPS = `%s`\n", gomips)
 	fmt.Fprintf(&buf, "const defaultGOMIPS64 = `%s`\n", gomips64)
diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index 14840efb22..5cb32c80e9 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -1852,6 +1852,9 @@
 // 	GOARM
 // 		For GOARCH=arm, the ARM architecture for which to compile.
 // 		Valid values are 5, 6, 7.
+// 	GO386
+// 		For GOARCH=386, how to implement floating point instructions.
+// 		Valid values are sse2 (default), softfloat.
 // 	GOMIPS
 // 		For GOARCH=mips{,le}, whether to use floating point instructions.
 // 		Valid values are hardfloat (default), softfloat.
diff --git a/src/cmd/go/internal/cfg/cfg.go b/src/cmd/go/internal/cfg/cfg.go
index 9169c12d8f..67d581f6e6 100644
--- a/src/cmd/go/internal/cfg/cfg.go
+++ b/src/cmd/go/internal/cfg/cfg.go
@@ -256,6 +256,7 @@ var (
 
 	// Used in envcmd.MkEnv and build ID computations.
 	GOARM    = envOr("GOARM", fmt.Sprint(objabi.GOARM))
+	GO386    = envOr("GO386", objabi.GO386)
 	GOMIPS   = envOr("GOMIPS", objabi.GOMIPS)
 	GOMIPS64 = envOr("GOMIPS64", objabi.GOMIPS64)
 	GOPPC64  = envOr("GOPPC64", fmt.Sprintf("%s%d", "power", objabi.GOPPC64))
@@ -279,6 +280,8 @@ func GetArchEnv() (key, val string) {
 	switch Goarch {
 	case "arm":
 		return "GOARM", GOARM
+	case "386":
+		return "GO386", GO386
 	case "mips", "mipsle":
 		return "GOMIPS", GOMIPS
 	case "mips64", "mips64le":
diff --git a/src/cmd/go/internal/help/helpdoc.go b/src/cmd/go/internal/help/helpdoc.go
index befa10a0e4..8dfabbaa4a 100644
--- a/src/cmd/go/internal/help/helpdoc.go
+++ b/src/cmd/go/internal/help/helpdoc.go
@@ -581,6 +581,9 @@ Architecture-specific environment variables:
 	GOARM
 		For GOARCH=arm, the ARM architecture for which to compile.
 		Valid values are 5, 6, 7.
+	GO386
+		For GOARCH=386, how to implement floating point instructions.
+		Valid values are sse2 (default), softfloat.
 	GOMIPS
 		For GOARCH=mips{,le}, whether to use floating point instructions.
 		Valid values are hardfloat (default), softfloat.
diff --git a/src/cmd/internal/objabi/util.go b/src/cmd/internal/objabi/util.go
index cedb2d0a26..b81b73a022 100644
--- a/src/cmd/internal/objabi/util.go
+++ b/src/cmd/internal/objabi/util.go
@@ -24,6 +24,7 @@ var (
 	GOROOT   = envOr("GOROOT", defaultGOROOT)
 	GOARCH   = envOr("GOARCH", defaultGOARCH)
 	GOOS     = envOr("GOOS", defaultGOOS)
+	GO386    = envOr("GO386", defaultGO386)
 	GOAMD64  = goamd64()
 	GOARM    = goarm()
 	GOMIPS   = gomips()
@@ -135,14 +136,6 @@ func init() {
 	if GOARCH != "amd64" {
 		Regabi_enabled = 0
 	}
-
-	if v := os.Getenv("GO386"); v != "" && v != "sse2" {
-		msg := fmt.Sprintf("unsupported setting GO386=%s", v)
-		if v == "387" {
-			msg += ". 387 support was dropped in Go 1.16. Consider using gccgo instead."
-		}
-		log.Fatal(msg)
-	}
 }
 
 // Note: must agree with runtime.framepointer_enabled.
diff --git a/src/internal/cfg/cfg.go b/src/internal/cfg/cfg.go
index 023429e441..bdbe9df3e7 100644
--- a/src/internal/cfg/cfg.go
+++ b/src/internal/cfg/cfg.go
@@ -32,6 +32,7 @@ const KnownEnv = `
 	FC
 	GCCGO
 	GO111MODULE
+	GO386
 	GOARCH
 	GOARM
 	GOBIN
diff --git a/test/codegen/arithmetic.go b/test/codegen/arithmetic.go
index 30f39a8da1..0bdb66a376 100644
--- a/test/codegen/arithmetic.go
+++ b/test/codegen/arithmetic.go
@@ -125,7 +125,7 @@ func Mul_n120(n int) int {
 func MulMemSrc(a []uint32, b []float32) {
 	// 386:`IMULL\s4\([A-Z]+\),\s[A-Z]+`
 	a[0] *= a[1]
-	// 386:`MULSS\s4\([A-Z]+\),\sX[0-9]+`
+	// 386/sse2:`MULSS\s4\([A-Z]+\),\sX[0-9]+`
 	// amd64:`MULSS\s4\([A-Z]+\),\sX[0-9]+`
 	b[0] *= b[1]
 }
@@ -167,7 +167,7 @@ func MergeMuls5(a, n int) int {
 // -------------- //
 
 func DivMemSrc(a []float64) {
-	// 386:`DIVSD\s8\([A-Z]+\),\sX[0-9]+`
+	// 386/sse2:`DIVSD\s8\([A-Z]+\),\sX[0-9]+`
 	// amd64:`DIVSD\s8\([A-Z]+\),\sX[0-9]+`
 	a[0] /= a[1]
 }
@@ -211,7 +211,7 @@ func ConstDivs(n1 uint, n2 int) (uint, int) {
 
 func FloatDivs(a []float32) float32 {
 	// amd64:`DIVSS\s8\([A-Z]+\),\sX[0-9]+`
-	// 386:`DIVSS\s8\([A-Z]+\),\sX[0-9]+`
+	// 386/sse2:`DIVSS\s8\([A-Z]+\),\sX[0-9]+`
 	return a[1] / a[2]
 }
 
diff --git a/test/codegen/floats.go b/test/codegen/floats.go
index d115800a67..83b4a358a5 100644
--- a/test/codegen/floats.go
+++ b/test/codegen/floats.go
@@ -15,7 +15,7 @@ package codegen
 // --------------------- //
 
 func Mul2(f float64) float64 {
-	// 386:"ADDSD",-"MULSD"
+	// 386/sse2:"ADDSD",-"MULSD"
 	// amd64:"ADDSD",-"MULSD"
 	// arm/7:"ADDD",-"MULD"
 	// arm64:"FADDD",-"FMULD"
@@ -25,7 +25,7 @@ func Mul2(f float64) float64 {
 }
 
 func DivPow2(f1, f2, f3 float64) (float64, float64, float64) {
-	// 386:"MULSD",-"DIVSD"
+	// 386/sse2:"MULSD",-"DIVSD"
 	// amd64:"MULSD",-"DIVSD"
 	// arm/7:"MULD",-"DIVD"
 	// arm64:"FMULD",-"FDIVD"
@@ -33,7 +33,7 @@ func DivPow2(f1, f2, f3 float64) (float64, float64, float64) {
 	// ppc64le:"FMUL",-"FDIV"
 	x := f1 / 16.0
 
-	// 386:"MULSD",-"DIVSD"
+	// 386/sse2:"MULSD",-"DIVSD"
 	// amd64:"MULSD",-"DIVSD"
 	// arm/7:"MULD",-"DIVD"
 	// arm64:"FMULD",-"FDIVD"
@@ -41,7 +41,7 @@ func DivPow2(f1, f2, f3 float64) (float64, float64, float64) {
 	// ppc64le:"FMUL",-"FDIVD"
 	y := f2 / 0.125
 
-	// 386:"ADDSD",-"DIVSD",-"MULSD"
+	// 386/sse2:"ADDSD",-"DIVSD",-"MULSD"
 	// amd64:"ADDSD",-"DIVSD",-"MULSD"
 	// arm/7:"ADDD",-"MULD",-"DIVD"
 	// arm64:"FADDD",-"FMULD",-"FDIVD"
diff --git a/test/codegen/math.go b/test/codegen/math.go
index fe678eea23..ac8071400e 100644
--- a/test/codegen/math.go
+++ b/test/codegen/math.go
@@ -46,7 +46,7 @@ func approx(x float64) {
 
 func sqrt(x float64) float64 {
 	// amd64:"SQRTSD"
-	// 386:"SQRTSD"
+	// 386/sse2:"SQRTSD" 386/softfloat:-"SQRTD"
 	// arm64:"FSQRTD"
 	// arm/7:"SQRTD"
 	// mips/hardfloat:"SQRTD" mips/softfloat:-"SQRTD"
diff --git a/test/codegen/memops.go b/test/codegen/memops.go
index 4b003ad861..a234283146 100644
--- a/test/codegen/memops.go
+++ b/test/codegen/memops.go
@@ -175,33 +175,33 @@ func idxInt64(x, y []int64, i int) {
 
 func idxFloat32(x, y []float32, i int) {
 	var t float32
-	// amd64: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\), X[0-9]+`
-	//   386: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\), X[0-9]+`
+	//    amd64: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\), X[0-9]+`
+	// 386/sse2: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\), X[0-9]+`
 	t = x[i+1]
-	// amd64: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\)`
-	//   386: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\)`
+	//    amd64: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\)`
+	// 386/sse2: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*4\)`
 	y[i+1] = t
-	// amd64: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\), X[0-9]+`
-	//   386: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\), X[0-9]+`
+	//    amd64: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\), X[0-9]+`
+	// 386/sse2: `MOVSS\t4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\), X[0-9]+`
 	t = x[16*i+1]
-	// amd64: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\)`
-	//   386: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\)`
+	//    amd64: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\)`
+	// 386/sse2: `MOVSS\tX[0-9]+, 4\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[14]\)`
 	y[16*i+1] = t
 }
 
 func idxFloat64(x, y []float64, i int) {
 	var t float64
-	// amd64: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\), X[0-9]+`
-	//   386: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\), X[0-9]+`
+	//    amd64: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\), X[0-9]+`
+	// 386/sse2: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\), X[0-9]+`
 	t = x[i+1]
-	// amd64: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\)`
-	//   386: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\)`
+	//    amd64: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\)`
+	// 386/sse2: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*8\)`
 	y[i+1] = t
-	// amd64: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\), X[0-9]+`
-	//   386: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\), X[0-9]+`
+	//    amd64: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\), X[0-9]+`
+	// 386/sse2: `MOVSD\t8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\), X[0-9]+`
 	t = x[16*i+1]
-	// amd64: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\)`
-	//   386: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\)`
+	//    amd64: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\)`
+	// 386/sse2: `MOVSD\tX[0-9]+, 8\([A-Z]+[0-9]*\)\([A-Z]+[0-9]*\*[18]\)`
 	y[16*i+1] = t
 }
 
diff --git a/test/run.go b/test/run.go
index 77710fd89a..672861c8d7 100644
--- a/test/run.go
+++ b/test/run.go
@@ -1489,7 +1489,7 @@ var (
 	// value[0] is the variant-changing environment variable, and values[1:]
 	// are the supported variants.
 	archVariants = map[string][]string{
-		"386":     {},
+		"386":     {"GO386", "sse2", "softfloat"},
 		"amd64":   {},
 		"arm":     {"GOARM", "5", "6", "7"},
 		"arm64":   {},
@@ -1511,12 +1511,12 @@ type wantedAsmOpcode struct {
 	found    bool           // true if the opcode check matched at least one in the output
 }
 
-// A build environment triplet separated by slashes (eg: linux/arm/7).
+// A build environment triplet separated by slashes (eg: linux/386/sse2).
 // The third field can be empty if the arch does not support variants (eg: "plan9/amd64/")
 type buildEnv string
 
 // Environ returns the environment it represents in cmd.Environ() "key=val" format
-// For instance, "linux/arm/7".Environ() returns {"GOOS=linux", "GOARCH=arm", "GOARM=7"}
+// For instance, "linux/386/sse2".Environ() returns {"GOOS=linux", "GOARCH=386", "GO386=sse2"}
 func (b buildEnv) Environ() []string {
 	fields := strings.Split(string(b), "/")
 	if len(fields) != 3 {
@@ -1571,11 +1571,11 @@ func (t *test) wantedAsmOpcodes(fn string) asmChecks {
 
 			var arch, subarch, os string
 			switch {
-			case archspec[2] != "": // 3 components: "linux/arm/7"
+			case archspec[2] != "": // 3 components: "linux/386/sse2"
 				os, arch, subarch = archspec[0], archspec[1][1:], archspec[2][1:]
-			case archspec[1] != "": // 2 components: "arm/7"
+			case archspec[1] != "": // 2 components: "386/sse2"
 				os, arch, subarch = "linux", archspec[0], archspec[1][1:]
-			default: // 1 component: "arm"
+			default: // 1 component: "386"
 				os, arch, subarch = "linux", archspec[0], ""
 				if arch == "wasm" {
 					os = "js"