Index: llvm/trunk/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Scalar/GVN.cpp
+++ llvm/trunk/lib/Transforms/Scalar/GVN.cpp
@@ -98,6 +98,7 @@
 static cl::opt<bool> EnablePRE("enable-pre",
                                cl::init(true), cl::Hidden);
 static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
+static cl::opt<bool> EnableMemDep("enable-gvn-memdep", cl::init(true));
 
 // Maximum allowed recursion depth.
 static cl::opt<uint32_t>
@@ -393,18 +394,13 @@
     uint32_t e = assignExpNewValueNum(exp).first;
     valueNumbering[C] = e;
     return e;
-  } else if (AA->onlyReadsMemory(C)) {
+  } else if (MD && AA->onlyReadsMemory(C)) {
     Expression exp = createExpr(C);
     auto ValNum = assignExpNewValueNum(exp);
     if (ValNum.second) {
       valueNumbering[C] = ValNum.first;
       return ValNum.first;
     }
-    if (!MD) {
-      uint32_t e = assignExpNewValueNum(exp).first;
-      valueNumbering[C] = e;
-      return e;
-    }
 
     MemDepResult local_dep = MD->getDependency(C);
 
@@ -2520,8 +2516,8 @@
 public:
   static char ID; // Pass identification, replacement for typeid
 
-  explicit GVNLegacyPass(bool NoLoads = false)
-      : FunctionPass(ID), NoLoads(NoLoads) {
+  explicit GVNLegacyPass(bool NoMemDepAnalysis = !EnableMemDep)
+      : FunctionPass(ID), NoMemDepAnalysis(NoMemDepAnalysis) {
     initializeGVNLegacyPassPass(*PassRegistry::getPassRegistry());
   }
 
@@ -2536,7 +2532,7 @@
         getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
         getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
         getAnalysis<AAResultsWrapperPass>().getAAResults(),
-        NoLoads ? nullptr
+        NoMemDepAnalysis ? nullptr
                 : &getAnalysis<MemoryDependenceWrapperPass>().getMemDep(),
         LIWP ? &LIWP->getLoopInfo() : nullptr,
         &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE());
@@ -2546,7 +2542,7 @@
     AU.addRequired<AssumptionCacheTracker>();
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
-    if (!NoLoads)
+    if (!NoMemDepAnalysis)
       AU.addRequired<MemoryDependenceWrapperPass>();
     AU.addRequired<AAResultsWrapperPass>();
 
@@ -2557,7 +2553,7 @@
   }
 
 private:
-  bool NoLoads;
+  bool NoMemDepAnalysis;
   GVN Impl;
 };
 
@@ -2574,6 +2570,6 @@
 INITIALIZE_PASS_END(GVNLegacyPass, "gvn", "Global Value Numbering", false, false)
 
 // The public interface to this file...
-FunctionPass *llvm::createGVNPass(bool NoLoads) {
-  return new GVNLegacyPass(NoLoads);
+FunctionPass *llvm::createGVNPass(bool NoMemDepAnalysis) {
+  return new GVNLegacyPass(NoMemDepAnalysis);
 }
Index: llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll
===================================================================
--- llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll
+++ llvm/trunk/test/Transforms/GVN/no-mem-dep-info.ll
@@ -0,0 +1,29 @@
+; RUN: opt %s -gvn -S -enable-gvn-memdep=false | FileCheck %s
+; RUN: opt %s -gvn -S -enable-gvn-memdep=true | FileCheck %s
+
+; Check that llvm.x86.avx2.gather.d.ps.256 intrinsic is not eliminated by GVN
+; with and without memory dependence info.
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: nounwind readonly
+declare <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float>, i8*, <8 x i32>, <8 x float>, i8) #0
+
+; Function Attrs: nounwind
+define <8 x float> @foo1(i8* noalias readonly %arr.ptr, <8 x i32>* noalias readonly %vix.ptr, i8* noalias %t2.ptr) #1 {
+allocas:
+  %vix = load <8 x i32>, <8 x i32>* %vix.ptr, align 4
+  %t1.ptr = getelementptr i8, i8* %arr.ptr, i8 4
+
+  %v1 = tail call <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float> undef, i8* %arr.ptr, <8 x i32> %vix, <8 x float> <float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000>, i8 1) #2
+  store i8 1, i8* %t1.ptr, align 4
+
+  %v2 = tail call <8 x float> @llvm.x86.avx2.gather.d.ps.256(<8 x float> undef, i8* %arr.ptr, <8 x i32> %vix, <8 x float> <float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000, float 0xFFFFFFFFE0000000>, i8 1) #2
+  %res = fadd <8 x float> %v1, %v2
+
+  ret <8 x float> %res
+}
+; CHECK: foo1
+; CHECK: llvm.x86.avx2.gather.d.ps.256
+; CHECK: store
+; CHECK: llvm.x86.avx2.gather.d.ps.256