diff --git a/builtins.go b/builtins.go
index c37a1d7..bee1893 100644
--- a/builtins.go
+++ b/builtins.go
@@ -18,6 +18,8 @@ package jsonnet
 
 import (
 	"bytes"
+	"crypto/md5"
+	"encoding/hex"
 	"math"
 	"sort"
 
@@ -373,6 +375,15 @@ func builtinType(e *evaluator, xp potentialValue) (value, error) {
 	return makeValueString(x.typename()), nil
 }
 
+func builtinMd5(e *evaluator, xp potentialValue) (value, error) {
+	x, err := e.evaluateString(xp)
+	if err != nil {
+		return nil, err
+	}
+	hash := md5.Sum([]byte(string(x.value)))
+	return makeValueString(hex.EncodeToString(hash[:])), nil
+}
+
 func makeDoubleCheck(e *evaluator, x float64) (value, error) {
 	if math.IsNaN(x) {
 		return nil, e.Error("Not a number")
@@ -616,4 +627,5 @@ var funcBuiltins = map[string]evalCallable{
 	"exponent":        &UnaryBuiltin{name: "exponent", function: builtinExponent, parameters: ast.Identifiers{"x"}},
 	"pow":             &BinaryBuiltin{name: "pow", function: builtinPow, parameters: ast.Identifiers{"base", "exp"}},
 	"modulo":          &BinaryBuiltin{name: "modulo", function: builtinModulo, parameters: ast.Identifiers{"x", "y"}},
+	"md5":             &UnaryBuiltin{name: "md5", function: builtinMd5, parameters: ast.Identifiers{"x"}},
 }
diff --git a/testdata/std.md5.golden b/testdata/std.md5.golden
new file mode 100644
index 0000000..e929965
--- /dev/null
+++ b/testdata/std.md5.golden
@@ -0,0 +1 @@
+"f561aaf6ef0bf14d4208bb46a4ccb3ad"
diff --git a/testdata/std.md5.input b/testdata/std.md5.input
new file mode 100644
index 0000000..51960fc
--- /dev/null
+++ b/testdata/std.md5.input
@@ -0,0 +1 @@
+std.md5("xxx")
diff --git a/testdata/std.md5_2.golden b/testdata/std.md5_2.golden
new file mode 100644
index 0000000..96c8aef
--- /dev/null
+++ b/testdata/std.md5_2.golden
@@ -0,0 +1 @@
+"d41d8cd98f00b204e9800998ecf8427e"
diff --git a/testdata/std.md5_2.input b/testdata/std.md5_2.input
new file mode 100644
index 0000000..9e5f5fe
--- /dev/null
+++ b/testdata/std.md5_2.input
@@ -0,0 +1 @@
+std.md5("")
diff --git a/testdata/std.md5_3.golden b/testdata/std.md5_3.golden
new file mode 100644
index 0000000..85b993a
--- /dev/null
+++ b/testdata/std.md5_3.golden
@@ -0,0 +1 @@
+"0cc175b9c0f1b6a831c399e269772661"
diff --git a/testdata/std.md5_3.input b/testdata/std.md5_3.input
new file mode 100644
index 0000000..57ecc95
--- /dev/null
+++ b/testdata/std.md5_3.input
@@ -0,0 +1 @@
+std.md5("a")
diff --git a/testdata/std.md5_4.golden b/testdata/std.md5_4.golden
new file mode 100644
index 0000000..96a528e
--- /dev/null
+++ b/testdata/std.md5_4.golden
@@ -0,0 +1 @@
+"f96b697d7cb7938d525a2f31aaf161d0"
diff --git a/testdata/std.md5_4.input b/testdata/std.md5_4.input
new file mode 100644
index 0000000..12f0571
--- /dev/null
+++ b/testdata/std.md5_4.input
@@ -0,0 +1 @@
+std.md5("message digest")
diff --git a/testdata/std.md5_5.golden b/testdata/std.md5_5.golden
new file mode 100644
index 0000000..cefd4ec
--- /dev/null
+++ b/testdata/std.md5_5.golden
@@ -0,0 +1 @@
+"5786eab716295401c073064c3ec82a44"
diff --git a/testdata/std.md5_5.input b/testdata/std.md5_5.input
new file mode 100644
index 0000000..2f7bc68
--- /dev/null
+++ b/testdata/std.md5_5.input
@@ -0,0 +1 @@
+std.md5("ą")
diff --git a/testdata/std.md5_6.golden b/testdata/std.md5_6.golden
new file mode 100644
index 0000000..f94e054
--- /dev/null
+++ b/testdata/std.md5_6.golden
@@ -0,0 +1 @@
+RUNTIME ERROR: Unexpected type number, expected string
diff --git a/testdata/std.md5_6.input b/testdata/std.md5_6.input
new file mode 100644
index 0000000..2542a47
--- /dev/null
+++ b/testdata/std.md5_6.input
@@ -0,0 +1 @@
+std.md5(42)