diff --git a/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp b/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
index 5bad84ca896..b956ff33f0f 100644
--- a/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
+++ b/lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp
@@ -232,6 +232,14 @@ GenericValue lle_X_pow(MethodType *M, const vector<GenericValue> &Args) {
   return GV;
 }
 
+// double exp(double)
+GenericValue lle_X_exp(MethodType *M, const vector<GenericValue> &Args) {
+  assert(Args.size() == 1);
+  GenericValue GV;
+  GV.DoubleVal = exp(Args[0].DoubleVal);
+  return GV;
+}
+
 // double sqrt(double)
 GenericValue lle_X_sqrt(MethodType *M, const vector<GenericValue> &Args) {
   assert(Args.size() == 1);
@@ -398,6 +406,7 @@ void Interpreter::initializeExternalMethods() {
   FuncNames["lle_X_free"]         = lle_X_free;
   FuncNames["lle_X_atoi"]         = lle_X_atoi;
   FuncNames["lle_X_pow"]          = lle_X_pow;
+  FuncNames["lle_X_exp"]          = lle_X_exp;
   FuncNames["lle_X_log"]          = lle_X_log;
   FuncNames["lle_X_floor"]        = lle_X_floor;
   FuncNames["lle_X_srand"]        = lle_X_srand;