diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -685,6 +685,16 @@
       return true;
     }
 
+    /// Returns true if this StringRef has the given prefix, ignoring case,
+    /// and removes that prefix.
+    bool consume_front_lower(StringRef Prefix) {
+      if (!startswith_lower(Prefix))
+        return false;
+
+      *this = drop_front(Prefix.size());
+      return true;
+    }
+
     /// Returns true if this StringRef has the given suffix and removes that
     /// suffix.
     bool consume_back(StringRef Suffix) {
@@ -695,6 +705,16 @@
       return true;
     }
 
+    /// Returns true if this StringRef has the given suffix, ignoring case,
+    /// and removes that suffix.
+    bool consume_back_lower(StringRef Suffix) {
+      if (!endswith_lower(Suffix))
+        return false;
+
+      *this = drop_back(Suffix.size());
+      return true;
+    }
+
     /// Return a reference to the substring from [Start, End).
     ///
     /// \param Start The index of the starting character in the substring; if
diff --git a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
--- a/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
+++ b/llvm/lib/ToolDrivers/llvm-dlltool/DlltoolDriver.cpp
@@ -93,23 +93,16 @@
   return getMachine(Triple(sys::getDefaultTargetTriple()));
 }
 
-static bool consume_back_lower(StringRef &S, const char *Str) {
-  if (!S.endswith_lower(Str))
-    return false;
-  S = S.drop_back(strlen(Str));
-  return true;
-}
-
 Optional<std::string> getPrefix(StringRef Argv0) {
   StringRef ProgName = llvm::sys::path::stem(Argv0);
   // x86_64-w64-mingw32-dlltool -> x86_64-w64-mingw32
   // llvm-dlltool -> None
   // aarch64-w64-mingw32-llvm-dlltool-10.exe -> aarch64-w64-mingw32
   ProgName = ProgName.rtrim("0123456789.-");
-  if (!consume_back_lower(ProgName, "dlltool"))
+  if (!ProgName.consume_back_lower("dlltool"))
     return None;
-  consume_back_lower(ProgName, "llvm-");
-  consume_back_lower(ProgName, "-");
+  ProgName.consume_back_lower("llvm-");
+  ProgName.consume_back_lower("-");
   return ProgName.str();
 }
 
diff --git a/llvm/tools/llvm-rc/llvm-rc.cpp b/llvm/tools/llvm-rc/llvm-rc.cpp
--- a/llvm/tools/llvm-rc/llvm-rc.cpp
+++ b/llvm/tools/llvm-rc/llvm-rc.cpp
@@ -256,23 +256,16 @@
   return true;
 }
 
-static bool consume_back_lower(StringRef &S, const char *Str) {
-  if (!S.endswith_lower(Str))
-    return false;
-  S = S.drop_back(strlen(Str));
-  return true;
-}
-
 static std::pair<bool, std::string> isWindres(llvm::StringRef Argv0) {
   StringRef ProgName = llvm::sys::path::stem(Argv0);
   // x86_64-w64-mingw32-windres -> x86_64-w64-mingw32, windres
   // llvm-rc -> "", llvm-rc
   // aarch64-w64-mingw32-llvm-windres-10.exe -> aarch64-w64-mingw32, llvm-windres
   ProgName = ProgName.rtrim("0123456789.-");
-  if (!consume_back_lower(ProgName, "windres"))
+  if (!ProgName.consume_back_lower("windres"))
     return std::make_pair<bool, std::string>(false, "");
-  consume_back_lower(ProgName, "llvm-");
-  consume_back_lower(ProgName, "-");
+  ProgName.consume_back_lower("llvm-");
+  ProgName.consume_back_lower("-");
   return std::make_pair<bool, std::string>(true, ProgName.str());
 }
 
diff --git a/llvm/unittests/ADT/StringRefTest.cpp b/llvm/unittests/ADT/StringRefTest.cpp
--- a/llvm/unittests/ADT/StringRefTest.cpp
+++ b/llvm/unittests/ADT/StringRefTest.cpp
@@ -392,6 +392,24 @@
   EXPECT_TRUE(Str.consume_front(""));
 }
 
+TEST(StringRefTest, ConsumeFrontLower) {
+  StringRef Str("heLLo");
+  EXPECT_TRUE(Str.consume_front_lower(""));
+  EXPECT_EQ("heLLo", Str);
+  EXPECT_FALSE(Str.consume_front("HEl"));
+  EXPECT_EQ("heLLo", Str);
+  EXPECT_TRUE(Str.consume_front_lower("HEl"));
+  EXPECT_EQ("Lo", Str);
+  EXPECT_FALSE(Str.consume_front_lower("loworld"));
+  EXPECT_EQ("Lo", Str);
+  EXPECT_FALSE(Str.consume_front_lower("ol"));
+  EXPECT_EQ("Lo", Str);
+  EXPECT_TRUE(Str.consume_front_lower("lo"));
+  EXPECT_EQ("", Str);
+  EXPECT_FALSE(Str.consume_front_lower("o"));
+  EXPECT_TRUE(Str.consume_front_lower(""));
+}
+
 TEST(StringRefTest, EndsWith) {
   StringRef Str("hello");
   EXPECT_TRUE(Str.endswith(""));
@@ -427,6 +445,24 @@
   EXPECT_TRUE(Str.consume_back(""));
 }
 
+TEST(StringRefTest, ConsumeBackLower) {
+  StringRef Str("heLLo");
+  EXPECT_TRUE(Str.consume_back_lower(""));
+  EXPECT_EQ("heLLo", Str);
+  EXPECT_FALSE(Str.consume_back("lO"));
+  EXPECT_EQ("heLLo", Str);
+  EXPECT_TRUE(Str.consume_back_lower("lO"));
+  EXPECT_EQ("heL", Str);
+  EXPECT_FALSE(Str.consume_back_lower("helhel"));
+  EXPECT_EQ("heL", Str);
+  EXPECT_FALSE(Str.consume_back_lower("hle"));
+  EXPECT_EQ("heL", Str);
+  EXPECT_TRUE(Str.consume_back_lower("hEl"));
+  EXPECT_EQ("", Str);
+  EXPECT_FALSE(Str.consume_back_lower("h"));
+  EXPECT_TRUE(Str.consume_back_lower(""));
+}
+
 TEST(StringRefTest, Find) {
   StringRef Str("helloHELLO");
   StringRef LongStr("hellx xello hell ello world foo bar hello HELLO");