Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1219,7 +1219,7 @@
 /// for example 'force', means a decision has been made. So, we need to be
 /// careful NOT to add them if the user hasn't specifically asked so.
 class LoopVectorizeHints {
-  enum HintKind { HK_WIDTH, HK_UNROLL, HK_FORCE };
+  enum HintKind { HK_WIDTH, HK_UNROLL, HK_FORCE, HK_ISVECTORIZED };
 
   /// Hint - associates name and validation with the hint value.
   struct Hint {
@@ -1238,6 +1238,8 @@
         return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
       case HK_FORCE:
         return (Val <= 1);
+      case HK_ISVECTORIZED:
+        return (Val==0 || Val==1);
       }
       return false;
     }
@@ -1250,6 +1252,8 @@
   /// Vectorization forced
   Hint Force;
 
+  /// Already Vectorized
+  Hint IsVectorized;
   /// Return the loop metadata prefix.
   static StringRef Prefix() { return "llvm.loop."; }
 
@@ -1269,6 +1273,7 @@
               HK_WIDTH),
         Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
         Force("vectorize.enable", FK_Undefined, HK_FORCE),
+        IsVectorized("isvectorized", 0, HK_ISVECTORIZED),
         PotentiallyUnsafe(false), TheLoop(L), ORE(ORE) {
     // Populate values with existing loop metadata.
     getHintsFromMetadata();
@@ -1277,14 +1282,19 @@
     if (VectorizerParams::isInterleaveForced())
       Interleave.Value = VectorizerParams::VectorizationInterleave;
 
+    if (IsVectorized.Value != 1)
+      // If the vectorization width and interleaving count are both 1 then consider
+      // the loop to have been already vectorized because there's nothing more that we
+      // can do.
+      IsVectorized.Value = Width.Value == 1 && Interleave.Value == 1;
     DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()
           << "LV: Interleaving disabled by the pass manager\n");
   }
 
   /// Mark the loop L as already vectorized by setting the width to 1.
   void setAlreadyVectorized() {
-    Width.Value = Interleave.Value = 1;
-    Hint Hints[] = {Width, Interleave};
+    IsVectorized.Value = 1;
+    Hint Hints[] = {IsVectorized};
     writeHintsToMetadata(Hints);
   }
 
@@ -1301,9 +1311,7 @@
       return false;
     }
 
-    if (getWidth() == 1 && getInterleave() == 1) {
-      // FIXME: Add a separate metadata to indicate when the loop has already
-      // been vectorized instead of setting width and count to 1.
+    if (getIsVectorized() == 1) {
       DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n");
       // FIXME: Add interleave.disable metadata. This will allow
       // vectorize.disable to be used without disabling the pass and errors
@@ -1312,8 +1320,8 @@
                                           "AllDisabled", L->getStartLoc(),
                                           L->getHeader())
                << "loop not vectorized: vectorization and interleaving are "
-                  "explicitly disabled, or vectorize width and interleave "
-                  "count are both set to 1");
+                  "explicitly disabled, or the loop has already been "
+                  "vectorized");
       return false;
     }
 
@@ -1346,6 +1354,7 @@
 
   unsigned getWidth() const { return Width.Value; }
   unsigned getInterleave() const { return Interleave.Value; }
+  unsigned getIsVectorized() const { return IsVectorized.Value; }
   enum ForceKind getForce() const { return (ForceKind)Force.Value; }
 
   /// \brief If hints are provided that force vectorization, use the AlwaysPrint
@@ -1429,7 +1438,7 @@
       return;
     unsigned Val = C->getZExtValue();
 
-    Hint *Hints[] = {&Width, &Interleave, &Force};
+    Hint *Hints[] = {&Width, &Interleave, &Force, &IsVectorized};
     for (auto H : Hints) {
       if (Name == H->Name) {
         if (H->validate(Val))
Index: test/Transforms/LoopVectorize/X86/already-vectorized.ll
===================================================================
--- test/Transforms/LoopVectorize/X86/already-vectorized.ll
+++ test/Transforms/LoopVectorize/X86/already-vectorized.ll
@@ -39,9 +39,8 @@
 }
 
 ; Now, we check for the Hint metadata
-; CHECK: [[vect]] = distinct !{[[vect]], [[width:![0-9]+]], [[unroll:![0-9]+]]}
-; CHECK: [[width]] = !{!"llvm.loop.vectorize.width", i32 1}
-; CHECK: [[unroll]] = !{!"llvm.loop.interleave.count", i32 1}
-; CHECK: [[scalar]] = distinct !{[[scalar]], [[runtime_unroll:![0-9]+]], [[width]], [[unroll]]}
+; CHECK: [[vect]] = distinct !{[[vect]], [[width:![0-9]+]]}
+; CHECK: [[width]] = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK: [[scalar]] = distinct !{[[scalar]], [[runtime_unroll:![0-9]+]], [[width]]}
 ; CHECK: [[runtime_unroll]] = !{!"llvm.loop.unroll.runtime.disable"}
 
Index: test/Transforms/LoopVectorize/X86/vectorization-remarks-loopid-dbg.ll
===================================================================
--- test/Transforms/LoopVectorize/X86/vectorization-remarks-loopid-dbg.ll
+++ test/Transforms/LoopVectorize/X86/vectorization-remarks-loopid-dbg.ll
@@ -8,7 +8,7 @@
 
 ; VECTORIZED: remark: vectorization-remarks.c:17:8: vectorized loop (vectorization width: 4, interleaved count: 1)
 ; UNROLLED: remark: vectorization-remarks.c:17:8: interleaved loop (interleaved count: 4)
-; NONE: remark: vectorization-remarks.c:17:8: loop not vectorized: vectorization and interleaving are explicitly disabled, or vectorize width and interleave count are both set to 1
+; NONE: remark: vectorization-remarks.c:17:8: loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
Index: test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
===================================================================
--- test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
+++ test/Transforms/LoopVectorize/X86/vectorization-remarks-missed.ll
@@ -20,7 +20,7 @@
 ;   for (int i = 0; i < Length; i++)
 ;     A[i] = i;
 ; }
-; CHECK: remark: source.cpp:13:5: loop not vectorized: vectorization and interleaving are explicitly disabled, or vectorize width and interleave count are both set to 1
+; CHECK: remark: source.cpp:13:5: loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
 
 ; void test_array_bounds(int *A, int *B, int Length) {
 ; #pragma clang loop vectorize(enable)
@@ -67,7 +67,7 @@
 ; YAML-NEXT: DebugLoc:        { File: source.cpp, Line: 13, Column: 5 }
 ; YAML-NEXT: Function:        _Z13test_disabledPii
 ; YAML-NEXT: Args:
-; YAML-NEXT:   - String:          'loop not vectorized: vectorization and interleaving are explicitly disabled, or vectorize width and interleave count are both set to 1'
+; YAML-NEXT:   - String:          'loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
 ; YAML-NEXT: ...
 ; YAML-NEXT: --- !Analysis
 ; YAML-NEXT: Pass:            ''
Index: test/Transforms/LoopVectorize/X86/vectorization-remarks.ll
===================================================================
--- test/Transforms/LoopVectorize/X86/vectorization-remarks.ll
+++ test/Transforms/LoopVectorize/X86/vectorization-remarks.ll
@@ -8,7 +8,7 @@
 
 ; VECTORIZED: remark: vectorization-remarks.c:17:8: vectorized loop (vectorization width: 4, interleaved count: 1)
 ; UNROLLED: remark: vectorization-remarks.c:17:8: interleaved loop (interleaved count: 4)
-; NONE: remark: vectorization-remarks.c:17:8: loop not vectorized: vectorization and interleaving are explicitly disabled, or vectorize width and interleave count are both set to 1
+; NONE: remark: vectorization-remarks.c:17:8: loop not vectorized: vectorization and interleaving are explicitly disabled, or the loop has already been vectorized
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
Index: test/Transforms/LoopVectorize/duplicated-metadata.ll
===================================================================
--- test/Transforms/LoopVectorize/duplicated-metadata.ll
+++ test/Transforms/LoopVectorize/duplicated-metadata.ll
@@ -26,4 +26,4 @@
 !0 = !{!0, !1}
 !1 = !{!"llvm.loop.vectorize.width", i32 4}
 ; CHECK-NOT: !{metadata !"llvm.loop.vectorize.width", i32 4}
-; CHECK: !{!"llvm.loop.interleave.count", i32 1}
+; CHECK: !{!"llvm.loop.isvectorized", i32 1}
Index: test/Transforms/LoopVectorize/multiple-strides-vectorization.ll
===================================================================
--- test/Transforms/LoopVectorize/multiple-strides-vectorization.ll
+++ test/Transforms/LoopVectorize/multiple-strides-vectorization.ll
@@ -25,7 +25,7 @@
 ; CHECK-LABEL: Test
 ; CHECK: <4 x i64>
 ; CHECK: <4 x i32>, <4 x i32>
-; CHECK: llvm.loop.vectorize.width
+; CHECK: !{!"llvm.loop.isvectorized", i32 1}
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 
Index: test/Transforms/LoopVectorize/vectorize-once.ll
===================================================================
--- test/Transforms/LoopVectorize/vectorize-once.ll
+++ test/Transforms/LoopVectorize/vectorize-once.ll
@@ -67,11 +67,10 @@
 
 attributes #0 = { nounwind readonly ssp uwtable "fp-contract-model"="standard" "no-frame-pointer-elim" "no-frame-pointer-elim-non-leaf" "realign-stack" "relocation-model"="pic" "ssp-buffers-size"="8" }
 
-; CHECK: !0 = distinct !{!0, !1, !2}
-; CHECK: !1 = !{!"llvm.loop.vectorize.width", i32 1}
-; CHECK: !2 = !{!"llvm.loop.interleave.count", i32 1}
-; CHECK: !3 = distinct !{!3, !4, !1, !2}
-; CHECK: !4 = !{!"llvm.loop.unroll.runtime.disable"}
+; CHECK: !0 = distinct !{!0, !1}
+; CHECK: !1 = !{!"llvm.loop.isvectorized", i32 1}
+; CHECK: !2 = distinct !{!2, !3, !1}
+; CHECK: !3 = !{!"llvm.loop.unroll.runtime.disable"}
 
 !0 = !{!0, !1}
 !1 = !{!"llvm.loop.vectorize.width", i32 1}