diff --git a/unittests/ADT/APFloatTest.cpp b/unittests/ADT/APFloatTest.cpp
index 92f020b..d2a977a 100644
--- a/unittests/ADT/APFloatTest.cpp
+++ b/unittests/ADT/APFloatTest.cpp
@@ -8,10 +8,12 @@
 //===----------------------------------------------------------------------===//
 
 #include <ostream>
+#include <string>
 #include "llvm/Support/raw_ostream.h"
 #include "gtest/gtest.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
 
 using namespace llvm;
 
@@ -21,6 +23,13 @@
   return F.convertToDouble();
 }
 
+static std::string convertToString(double d, unsigned Prec, unsigned Pad) {
+  llvm::SmallVector<char, 100> Buffer;
+  llvm::APFloat F(d);
+  F.toString(Buffer, Prec, Pad);
+  return std::string(Buffer.data(), Buffer.size());
+}
+
 namespace {
 
 TEST(APFloatTest, Zero) {
@@ -313,6 +322,17 @@
   EXPECT_EQ(2.71828, convertToDoubleFromString("2.71828"));
 }
 
+TEST(APFloatTest, toString) {
+  ASSERT_EQ("10", convertToString(10.0, 6, 3));
+  ASSERT_EQ("1.0E+1", convertToString(10.0, 6, 0));
+  ASSERT_EQ("10100", convertToString(1.01E+4, 5, 2));
+  ASSERT_EQ("1.01E+4", convertToString(1.01E+4, 4, 2));
+  ASSERT_EQ("1.01E+4", convertToString(1.01E+4, 5, 1));
+  ASSERT_EQ("0.0101", convertToString(1.01E-2, 5, 2));
+  ASSERT_EQ("1.01E-2", convertToString(1.01E-2, 4, 2));
+  ASSERT_EQ("1.01E-2", convertToString(1.01E-2, 5, 1));
+}
+
 #ifdef GTEST_HAS_DEATH_TEST
 TEST(APFloatTest, SemanticsDeath) {
   EXPECT_DEATH(APFloat(APFloat::IEEEsingle, 0.0f).convertToDouble(), "Float semantics are not IEEEdouble");