Index: include/llvm/Option/ArgList.h
===================================================================
--- include/llvm/Option/ArgList.h
+++ include/llvm/Option/ArgList.h
@@ -45,7 +45,7 @@
   // efficiently compared and returns them in order.
   OptSpecifier Id0, Id1, Id2;
 
-  void SkipToNextArg();
+  void skipToArg(bool Forward);
 
 public:
   typedef Arg * const *                 value_type;
@@ -58,7 +58,7 @@
                OptSpecifier Id0 = 0U, OptSpecifier Id1 = 0U,
                OptSpecifier Id2 = 0U)
       : Current(it), Args(Args), Id0(Id0), Id1(Id1), Id2(Id2) {
-    SkipToNextArg();
+    skipToArg(true /*Forward*/);
   }
 
   operator const Arg*() { return *Current; }
@@ -67,14 +67,26 @@
 
   arg_iterator &operator++() {
     ++Current;
-    SkipToNextArg();
+    skipToArg(true /*Forward*/);
     return *this;
   }
 
   arg_iterator operator++(int) {
-    arg_iterator tmp(*this);
+    arg_iterator Ret(*this);
     ++(*this);
-    return tmp;
+    return Ret;
+  }
+
+  arg_iterator &operator--() {
+    --Current;
+    skipToArg(false /*Forward*/);
+    return *this;
+  }
+
+  arg_iterator operator--(int) {
+    arg_iterator Ret(*this);
+    --(*this);
+    return Ret;
   }
 
   friend bool operator==(arg_iterator LHS, arg_iterator RHS) {
@@ -155,14 +167,16 @@
                               OptSpecifier Id2 = 0U) const {
     return arg_iterator(Args.begin(), *this, Id0, Id1, Id2);
   }
-  arg_iterator filtered_end() const {
-    return arg_iterator(Args.end(), *this);
+  arg_iterator filtered_end(OptSpecifier Id0 = 0U, OptSpecifier Id1 = 0U,
+                            OptSpecifier Id2 = 0U) const {
+    return arg_iterator(Args.end(), *this, Id0, Id1, Id2);
   }
 
   iterator_range<arg_iterator> filtered(OptSpecifier Id0 = 0U,
                                         OptSpecifier Id1 = 0U,
                                         OptSpecifier Id2 = 0U) const {
-    return make_range(filtered_begin(Id0, Id1, Id2), filtered_end());
+    return make_range(filtered_begin(Id0, Id1, Id2),
+                      filtered_end(Id0, Id1, Id2));
   }
 
   /// @}
Index: lib/Option/ArgList.cpp
===================================================================
--- lib/Option/ArgList.cpp
+++ lib/Option/ArgList.cpp
@@ -19,18 +19,21 @@
 using namespace llvm;
 using namespace llvm::opt;
 
-void arg_iterator::SkipToNextArg() {
-  for (; Current != Args.end(); ++Current) {
+void arg_iterator::skipToArg(bool Forward) {
+  auto End = Forward ? Args.end() : Args.begin();
+
+  while (Current != End) {
     // Done if there are no filters.
     if (!Id0.isValid())
       break;
 
     // Otherwise require a match.
     const Option &O = (*Current)->getOption();
-    if (O.matches(Id0) ||
-        (Id1.isValid() && O.matches(Id1)) ||
+    if (O.matches(Id0) || (Id1.isValid() && O.matches(Id1)) ||
         (Id2.isValid() && O.matches(Id2)))
       break;
+
+    Current += Forward ? 1 : -1;
   }
 }
 
Index: unittests/Option/OptionParsingTest.cpp
===================================================================
--- unittests/Option/OptionParsingTest.cpp
+++ unittests/Option/OptionParsingTest.cpp
@@ -105,6 +105,23 @@
   ASSERT_EQ(2u, ASL.size());
   EXPECT_EQ("-C", StringRef(ASL[0]));
   EXPECT_EQ("desu", StringRef(ASL[1]));
+
+  // Test iterator operators.
+  arg_iterator CsIt = AL.filtered_begin(OPT_C);
+  arg_iterator CsOp1 = CsIt++;
+  EXPECT_EQ("desu", StringRef((*CsOp1)->getValue()));
+  EXPECT_EQ("bye", StringRef((*CsIt)->getValue()));
+  arg_iterator CsOp2 = CsIt--;
+  EXPECT_EQ("bye", StringRef((*CsOp2)->getValue()));
+  EXPECT_EQ("desu", StringRef((*CsIt)->getValue()));
+  arg_iterator CsOp3 = ++CsIt;
+  EXPECT_EQ("bye", StringRef((*CsOp3)->getValue()));
+  EXPECT_EQ("bye", StringRef((*CsIt)->getValue()));
+  arg_iterator CsOp4 = --CsIt;
+  EXPECT_EQ("desu", StringRef((*CsOp4)->getValue()));
+  EXPECT_EQ("desu", StringRef((*CsIt)->getValue()));
+  arg_iterator CsItEnd = AL.filtered_end(OPT_C);
+  EXPECT_EQ("bye", StringRef((*--CsItEnd)->getValue()));
 }
 
 TEST(Option, ParseWithFlagExclusions) {