diff --git a/doc/manual/builtins.xml b/doc/manual/builtins.xml
index b6c886199..4c8e3163b 100644
--- a/doc/manual/builtins.xml
+++ b/doc/manual/builtins.xml
@@ -441,6 +441,15 @@ in config.someSetting</programlisting>
   -->
 
   
+  <varlistentry><term><function>builtins.readFile</function>
+  <replaceable>path</replaceable></term>
+
+    <listitem><para>Return the contents of the file
+    <replaceable>path</replaceable> as a string.</para></listitem>
+
+  </varlistentry>
+  
+  
   <varlistentry><term><function>removeAttrs</function>
   <replaceable>attrs</replaceable> <replaceable>list</replaceable></term>
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 2a96e25a8..bb9190579 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -622,6 +622,17 @@ static Expr prim_dirOf(EvalState & state, const ATermVector & args)
 }
 
 
+/* Return the contents of a file as a string. */
+static Expr prim_readFile(EvalState & state, const ATermVector & args)
+{
+    PathSet context;
+    Path path = coerceToPath(state, args[0], context);
+    if (!context.empty())
+        throw EvalError(format("string `%1%' cannot refer to other paths") % path);
+    return makeStr(readFile(path));
+}
+
+
 /*************************************************************
  * Creating files
  *************************************************************/
@@ -968,6 +979,7 @@ void EvalState::addPrimOps()
     addPrimOp("__pathExists", 1, prim_pathExists);
     addPrimOp("baseNameOf", 1, prim_baseNameOf);
     addPrimOp("dirOf", 1, prim_dirOf);
+    addPrimOp("__readFile", 1, prim_readFile);
 
     // Creating files
     addPrimOp("__toXML", 1, prim_toXML);
diff --git a/tests/lang/eval-okay-readfile.exp b/tests/lang/eval-okay-readfile.exp
new file mode 100644
index 000000000..979771c7a
--- /dev/null
+++ b/tests/lang/eval-okay-readfile.exp
@@ -0,0 +1 @@
+Str("builtins.readFile ./eval-okay-readfile.nix\n",[])
diff --git a/tests/lang/eval-okay-readfile.nix b/tests/lang/eval-okay-readfile.nix
new file mode 100644
index 000000000..82f7cb174
--- /dev/null
+++ b/tests/lang/eval-okay-readfile.nix
@@ -0,0 +1 @@
+builtins.readFile ./eval-okay-readfile.nix