Index: lib/Transforms/Scalar/LoopRotation.cpp
===================================================================
--- lib/Transforms/Scalar/LoopRotation.cpp
+++ lib/Transforms/Scalar/LoopRotation.cpp
@@ -82,6 +82,9 @@
   if (skipOptnoneFunction(L))
     return false;
 
+  // Save the loop metadata.
+  MDNode *LoopMD = L->getLoopID();
+
   LI = &getAnalysis<LoopInfo>();
   TTI = &getAnalysis<TargetTransformInfo>();
 
@@ -96,6 +99,12 @@
     MadeChange = true;
     SimplifiedLatch = false;
   }
+
+  // Restore the loop metadata.
+  // NB! We presume LoopRotation DOESN'T ADD its own metadata.
+  if ((MadeChange || SimplifiedLatch) && LoopMD)
+    L->setLoopID(LoopMD);
+
   return MadeChange;
 }
 
Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1067,7 +1067,8 @@
       return false;
 
     if (DL == NULL) {
-      DEBUG(dbgs() << "LV: Not vectorizing: Missing data layout\n");
+      DEBUG(dbgs() << "\nLV: Not vectorizing " << F.getName()
+                   << ": Missing data layout\n");
       return false;
     }
 
@@ -1090,13 +1091,20 @@
 
   bool processLoop(Loop *L) {
     assert(L->empty() && "Only process inner loops.");
-    DEBUG(dbgs() << "LV: Checking a loop in \""
+    DEBUG(dbgs() << "\nLV: Checking a loop in \""
                  << L->getHeader()->getParent()->getName() << "\" from "
                  << getDebugLocString(L->getHeader()->getFirstNonPHIOrDbg())
                  << "\n");
 
     LoopVectorizeHints Hints(L, DisableUnrolling);
 
+    DEBUG(dbgs() << "LV: Loop hints:"
+                 << " force=" << (Hints.Force == 0
+                                      ? "disabled"
+                                      : (Hints.Force == 1 ? "enabled" : "?"))
+                 << " width=" << Hints.Width << " unroll=" << Hints.Unroll
+                 << "\n");
+
     if (Hints.Force == 0) {
       DEBUG(dbgs() << "LV: Not vectorizing: #pragma vectorize disable.\n");
       return false;
@@ -1150,10 +1158,10 @@
     }
 
     // Select the optimal vectorization factor.
-    LoopVectorizationCostModel::VectorizationFactor VF;
-    VF = CM.selectVectorizationFactor(OptForSize, Hints.Width);
+    const LoopVectorizationCostModel::VectorizationFactor VF =
+                          CM.selectVectorizationFactor(OptForSize, Hints.Width);
     // Select the unroll factor.
-    unsigned UF = CM.selectUnrollFactor(OptForSize, Hints.Unroll, VF.Width,
+    const unsigned UF = CM.selectUnrollFactor(OptForSize, Hints.Unroll, VF.Width,
                                         VF.Cost);
 
     DEBUG(dbgs() << "LV: Found a vectorizable loop ("
@@ -5076,7 +5084,7 @@
     }
   }
 
-  DEBUG(dbgs() << "LV: Selecting VF = : "<< Width << ".\n");
+  DEBUG(dbgs() << "LV: Selecting VF: "<< Width << ".\n");
   Factor.Width = Width;
   Factor.Cost = Width * Cost;
   return Factor;
Index: test/Transforms/LoopVectorize/vect.omp.persistence.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoopVectorize/vect.omp.persistence.ll
@@ -0,0 +1,87 @@
+; RUN: opt < %s -O2 -force-vector-unroll=2 -force-vector-width=4 -debug-only=loop-vectorize -stats -S 2>&1 | FileCheck %s
+
+; Loop from "rotated"
+; CHECK: LV: Loop hints: force=enabled
+; Loop from "nonrotated"
+; CHECK: LV: Loop hints: force=enabled
+; No more loops in the module
+; CHECK-NOT: LV: Loop hints: force=
+; In total only 1 loop should be rotated.
+; CHECK: 1 loop-rotate
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; See http://reviews.llvm.org/D3348 for details.
+
+;
+; Test #1
+;
+; Ensure that "llvm.vectorizer.enable" metadata was not lost prior to LoopVectorize pass.
+; In past LoopRotate was clearing that metadata.
+;
+; The source C code is:
+; void rotated(float *a, int size)
+; {
+;   int t = 0;
+;   #pragma omp simd
+;   for (int i = 0; i < size; ++i) {
+;     a[i] = a[i-5] * a[i+2];
+;     ++t;
+;   }
+;}
+
+define void @rotated(float* nocapture %a, i64 %size) {
+entry:
+  %cmp1 = icmp sgt i64 %size, 0
+  br i1 %cmp1, label %for.header, label %for.end
+
+for.header:
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
+  %cmp2 = icmp sgt i64 %indvars.iv, %size
+  br i1 %cmp2, label %for.end, label %for.body
+
+for.body:
+
+  %0 = add nsw i64 %indvars.iv, -5
+  %arrayidx = getelementptr inbounds float* %a, i64 %0
+  %1 = load float* %arrayidx, align 4, !llvm.mem.parallel_loop_access !1
+  %2 = add nsw i64 %indvars.iv, 2
+  %arrayidx2 = getelementptr inbounds float* %a, i64 %2
+  %3 = load float* %arrayidx2, align 4, !llvm.mem.parallel_loop_access !1
+  %mul = fmul float %1, %3
+  %arrayidx4 = getelementptr inbounds float* %a, i64 %indvars.iv
+  store float %mul, float* %arrayidx4, align 4, !llvm.mem.parallel_loop_access !1
+
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  br label %for.header, !llvm.loop !1
+
+for.end:
+  ret void
+}
+
+!1 = metadata !{metadata !1, metadata !2}
+!2 = metadata !{metadata !"llvm.vectorizer.enable", i1 true}
+
+;
+; Test #2
+;
+; Ensure that "llvm.vectorizer.enable" metadata was not lost even
+; if loop was not rotated (see http://reviews.llvm.org/D3348#comment-4).
+;
+define i32 @nonrotated(i32 %a) {
+entry:
+  br label %loop_cond
+loop_cond:
+  %indx = phi i32 [ 1, %entry ], [ %inc, %loop_inc ]
+  %cmp = icmp ne i32 %indx, %a
+  br i1 %cmp, label %return, label %loop_inc
+loop_inc:
+  %inc = add i32 %indx, 1
+  br label %loop_cond, !llvm.loop !3
+return:
+  ret i32 0
+}
+
+!3 = metadata !{metadata !3, metadata !4}
+!4 = metadata !{metadata !"llvm.vectorizer.enable", i1 true}