diff --git a/include/llvm/ADT/StringRef.h b/include/llvm/ADT/StringRef.h
index 4e81b842526..a5c43fa631c 100644
--- a/include/llvm/ADT/StringRef.h
+++ b/include/llvm/ADT/StringRef.h
@@ -152,8 +152,8 @@ namespace llvm {
     ///
     /// \return - The index of the first occurence of \arg C, or npos if not
     /// found.
-    size_t find(char C) const {
-      for (size_t i = 0, e = Length; i != e; ++i)
+    size_t find(char C, size_t From = 0) const {
+      for (size_t i = std::min(From, Length), e = Length; i != e; ++i)
         if (Data[i] == C)
           return i;
       return npos;
@@ -163,7 +163,7 @@ namespace llvm {
     ///
     /// \return - The index of the first occurence of \arg Str, or npos if not
     /// found.
-    size_t find(StringRef Str) const;
+    size_t find(StringRef Str, size_t From = 0) const;
 
     /// rfind - Search for the last character \arg C in the string.
     ///
@@ -186,17 +186,25 @@ namespace llvm {
     /// found.
     size_t rfind(StringRef Str) const;
 
-    /// find_first_of - Find the first instance of the specified character or
-    /// return npos if not in string.  Same as find.
-    size_type find_first_of(char C) const { return find(C); }
+    /// find_first_of - Find the first character in the string that is \arg C,
+    /// or npos if not found. Same as find.
+    size_type find_first_of(char C, size_t From = 0) const { return find(C); }
 
-    /// find_first_of - Find the first character from the string 'Chars' in the
-    /// current string or return npos if not in string.
-    size_type find_first_of(StringRef Chars) const;
+    /// find_first_of - Find the first character in the string that is in \arg
+    /// Chars, or npos if not found.
+    ///
+    /// Note: O(size() * Chars.size())
+    size_type find_first_of(StringRef Chars, size_t From = 0) const;
 
     /// find_first_not_of - Find the first character in the string that is not
-    /// in the string 'Chars' or return npos if all are in string. Same as find.
-    size_type find_first_not_of(StringRef Chars) const;
+    /// \arg C or npos if not found.
+    size_type find_first_not_of(char C, size_t From = 0) const;
+
+    /// find_first_not_of - Find the first character in the string that is not
+    /// in the string \arg Chars, or npos if not found.
+    ///
+    /// Note: O(size() * Chars.size())
+    size_type find_first_not_of(StringRef Chars, size_t From = 0) const;
 
     /// @}
     /// @name Helpful Algorithms
diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 3f3ee5b3ead..6905edf19e1 100644
--- a/lib/Support/StringRef.cpp
+++ b/lib/Support/StringRef.cpp
@@ -24,11 +24,11 @@ const size_t StringRef::npos;
 ///
 /// \return - The index of the first occurence of \arg Str, or npos if not
 /// found.
-size_t StringRef::find(StringRef Str) const {
+size_t StringRef::find(StringRef Str, size_t From) const {
   size_t N = Str.size();
   if (N > Length)
     return npos;
-  for (size_t i = 0, e = Length - N + 1; i != e; ++i)
+  for (size_t e = Length - N + 1, i = std::min(From, e); i != e; ++i)
     if (substr(i, N).equals(Str))
       return i;
   return npos;
@@ -50,19 +50,34 @@ size_t StringRef::rfind(StringRef Str) const {
   return npos;
 }
 
-/// find_first_of - Find the first character from the string 'Chars' in the
-/// current string or return npos if not in string.
-StringRef::size_type StringRef::find_first_of(StringRef Chars) const {
-  for (size_type i = 0, e = Length; i != e; ++i)
+/// find_first_of - Find the first character in the string that is in \arg
+/// Chars, or npos if not found.
+///
+/// Note: O(size() * Chars.size())
+StringRef::size_type StringRef::find_first_of(StringRef Chars,
+                                              size_t From) const {
+  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
     if (Chars.find(Data[i]) != npos)
       return i;
   return npos;
 }
 
 /// find_first_not_of - Find the first character in the string that is not
-/// in the string 'Chars' or return npos if all are in string. Same as find.
-StringRef::size_type StringRef::find_first_not_of(StringRef Chars) const {
-  for (size_type i = 0, e = Length; i != e; ++i)
+/// \arg C or npos if not found.
+StringRef::size_type StringRef::find_first_not_of(char C, size_t From) const {
+  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
+    if (Data[i] != C)
+      return i;
+  return npos;
+}
+
+/// find_first_not_of - Find the first character in the string that is not
+/// in the string \arg Chars, or npos if not found.
+///
+/// Note: O(size() * Chars.size())
+StringRef::size_type StringRef::find_first_not_of(StringRef Chars,
+                                                  size_t From) const {
+  for (size_type i = std::min(From, Length), e = Length; i != e; ++i)
     if (Chars.find(Data[i]) == npos)
       return i;
   return npos;
diff --git a/unittests/ADT/StringRefTest.cpp b/unittests/ADT/StringRefTest.cpp
index cdc476e592b..7828b5fadf2 100644
--- a/unittests/ADT/StringRefTest.cpp
+++ b/unittests/ADT/StringRefTest.cpp
@@ -125,6 +125,8 @@ TEST(StringRefTest, Find) {
   EXPECT_EQ(0U, Str.find("hello"));
   EXPECT_EQ(1U, Str.find("ello"));
   EXPECT_EQ(StringRef::npos, Str.find("zz"));
+  EXPECT_EQ(2U, Str.find("ll", 2));
+  EXPECT_EQ(StringRef::npos, Str.find("ll", 3));
 
   EXPECT_EQ(3U, Str.rfind('l'));
   EXPECT_EQ(StringRef::npos, Str.rfind('z'));
@@ -132,6 +134,14 @@ TEST(StringRefTest, Find) {
   EXPECT_EQ(0U, Str.rfind("hello"));
   EXPECT_EQ(1U, Str.rfind("ello"));
   EXPECT_EQ(StringRef::npos, Str.rfind("zz"));
+
+  EXPECT_EQ(2U, Str.find_first_of('l'));
+  EXPECT_EQ(1U, Str.find_first_of("el"));
+  EXPECT_EQ(StringRef::npos, Str.find_first_of("xyz"));
+
+  EXPECT_EQ(1U, Str.find_first_not_of('h'));
+  EXPECT_EQ(4U, Str.find_first_not_of("hel"));
+  EXPECT_EQ(StringRef::npos, Str.find_first_not_of("hello"));
 }
 
 TEST(StringRefTest, Count) {