diff --git a/builder/library.go b/builder/library.go
index 53ae5d9d6..ca0ff779f 100644
--- a/builder/library.go
+++ b/builder/library.go
@@ -15,6 +15,9 @@ import (
 
 // Library is a container for information about a single C library, such as a
 // compiler runtime or libc.
+//
+// Note: whenever a library gets changed, the version in compileopts/config.go
+// probably also needs to be incremented.
 type Library struct {
 	// The library name, such as compiler-rt or picolibc.
 	name string
@@ -50,7 +53,7 @@ type Library struct {
 // As a side effect, this call creates the library header files if they didn't
 // exist yet.
 func (l *Library) load(config *compileopts.Config, tmpdir string) (job *compileJob, abortLock func(), err error) {
-	outdir := config.LibcPath(l.name)
+	outdir := config.LibraryPath(l.name)
 	archiveFilePath := filepath.Join(outdir, "lib.a")
 
 	// Create a lock on the output (if supported).
diff --git a/compileopts/config.go b/compileopts/config.go
index 9fa482952..6cc87aabd 100644
--- a/compileopts/config.go
+++ b/compileopts/config.go
@@ -8,12 +8,23 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 
 	"github.com/google/shlex"
 	"github.com/tinygo-org/tinygo/goenv"
 )
 
+// Library versions. Whenever an existing library is changed, this number should
+// be added/increased so that existing caches are invalidated.
+//
+// (This is a bit of a layering violation, this should really be part of the
+// builder.Library struct but that's hard to do since we want to know the
+// library path in advance in several places).
+var libVersions = map[string]int{
+	"musl": 2,
+}
+
 // Config keeps all configuration affecting the build in a single struct.
 type Config struct {
 	Options        *Options
@@ -247,9 +258,9 @@ func MuslArchitecture(triple string) string {
 	return CanonicalArchName(triple)
 }
 
-// LibcPath returns the path to the libc directory. The libc path will be a libc
-// path in the cache directory (which might not yet be built).
-func (c *Config) LibcPath(name string) string {
+// LibraryPath returns the path to the library build directory. The path will be
+// a library path in the cache directory (which might not yet be built).
+func (c *Config) LibraryPath(name string) string {
 	archname := c.Triple()
 	if c.CPU() != "" {
 		archname += "-" + c.CPU()
@@ -265,6 +276,11 @@ func (c *Config) LibcPath(name string) string {
 		archname += "-" + c.Target.Libc
 	}
 
+	// Append a version string, if this library has a version.
+	if v, ok := libVersions[name]; ok {
+		archname += "-v" + strconv.Itoa(v)
+	}
+
 	// No precompiled library found. Determine the path name that will be used
 	// in the build cache.
 	return filepath.Join(goenv.Get("GOCACHE"), name+"-"+archname)
@@ -351,7 +367,7 @@ func (c *Config) LibcCFlags() []string {
 	case "picolibc":
 		root := goenv.Get("TINYGOROOT")
 		picolibcDir := filepath.Join(root, "lib", "picolibc", "newlib", "libc")
-		path := c.LibcPath("picolibc")
+		path := c.LibraryPath("picolibc")
 		return []string{
 			"-nostdlibinc",
 			"-isystem", filepath.Join(path, "include"),
@@ -361,7 +377,7 @@ func (c *Config) LibcCFlags() []string {
 		}
 	case "musl":
 		root := goenv.Get("TINYGOROOT")
-		path := c.LibcPath("musl")
+		path := c.LibraryPath("musl")
 		arch := MuslArchitecture(c.Triple())
 		return []string{
 			"-nostdlibinc",
@@ -371,7 +387,7 @@ func (c *Config) LibcCFlags() []string {
 			"-isystem", filepath.Join(root, "lib", "musl", "include"),
 		}
 	case "wasi-libc":
-		path := c.LibcPath("wasi-libc")
+		path := c.LibraryPath("wasi-libc")
 		return []string{
 			"-nostdlibinc",
 			"-isystem", filepath.Join(path, "include"),
@@ -381,7 +397,7 @@ func (c *Config) LibcCFlags() []string {
 		return nil
 	case "mingw-w64":
 		root := goenv.Get("TINYGOROOT")
-		path := c.LibcPath("mingw-w64")
+		path := c.LibraryPath("mingw-w64")
 		return []string{
 			"-nostdlibinc",
 			"-isystem", filepath.Join(path, "include"),