Index: lib/Transforms/IPO/MergeFunctions.cpp
===================================================================
--- lib/Transforms/IPO/MergeFunctions.cpp
+++ lib/Transforms/IPO/MergeFunctions.cpp
@@ -1119,6 +1119,9 @@
   /// again.
   void mergeTwoFunctions(Function *F, Function *G);
 
+  /// Update the range metadata used by loads in F so that F can replace G.
+  void mergeRangeMetadata(Function *F, const Function *G);
+
   /// Replace G with a thunk or an alias to F. Deletes G.
   void writeThunkOrAlias(Function *F, Function *G);
 
@@ -1343,6 +1346,8 @@
 
 // Merge two equivalent functions. Upon completion, Function G is deleted.
 void MergeFunctions::mergeTwoFunctions(Function *F, Function *G) {
+  mergeRangeMetadata(F, G);
+
   if (F->mayBeOverridden()) {
     assert(G->mayBeOverridden());
 
@@ -1376,6 +1381,51 @@
   ++NumFunctionsMerged;
 }
 
+// Update the range metadata used by loads in F so that F can replace G.
+void MergeFunctions::mergeRangeMetadata(Function *F, const Function *G) {
+  // Find all loads in F and their counterparts in G, then update the range
+  // metadata in F to be the union of the ranges in F and G. Iterate over the
+  // functions in CFG-order, the same way that compare does.
+  SmallVector<BasicBlock *, 8> FBBs;
+  SmallVector<const BasicBlock *, 8> GBBs;
+  SmallSet<const BasicBlock *, 128> VisitedBBs; // in terms of F.
+
+  FBBs.push_back(&F->getEntryBlock());
+  GBBs.push_back(&G->getEntryBlock());
+
+  VisitedBBs.insert(FBBs[0]);
+  while (!FBBs.empty()) {
+    BasicBlock *FBB = FBBs.pop_back_val();
+    const BasicBlock *GBB = GBBs.pop_back_val();
+
+    BasicBlock::iterator FI = FBB->begin(), FE = FBB->end();
+    BasicBlock::const_iterator GI = GBB->begin(), GE = GBB->end();
+    do {
+      if (LoadInst *FLI = dyn_cast<LoadInst>(FI)) {
+        const LoadInst *GLI = dyn_cast<LoadInst>(GI);
+        assert(GLI);
+        FLI->setMetadata(LLVMContext::MD_range,
+                         MDNode::getMostGenericRange(
+                           FLI->getMetadata(LLVMContext::MD_range),
+                           GLI->getMetadata(LLVMContext::MD_range)));
+      }
+      ++FI; ++GI;
+    } while (FI != FE && GI != GE);
+
+    const TerminatorInst *FTI = FBB->getTerminator();
+    const TerminatorInst *GTI = GBB->getTerminator();
+
+    assert(FTI->getNumSuccessors() == GTI->getNumSuccessors());
+    for (unsigned i = 0, e = FTI->getNumSuccessors(); i != e; ++i) {
+      if (!VisitedBBs.insert(FTI->getSuccessor(i)))
+        continue;
+
+      FBBs.push_back(FTI->getSuccessor(i));
+      GBBs.push_back(GTI->getSuccessor(i));
+    }
+  }
+}
+
 // Insert a ComparableFunction into the FnSet, or merge it away if equal to one
 // that was already inserted.
 bool MergeFunctions::insert(ComparableFunction &NewF) {
Index: test/Transforms/MergeFunc/ranges.ll
===================================================================
--- /dev/null
+++ test/Transforms/MergeFunc/ranges.ll
@@ -0,0 +1,52 @@
+; RUN: opt -mergefunc -S < %s | FileCheck %s
+define i1 @ne_with_range(i8*, i8*) {
+; The range must be eliminated here, when this is merged with ne_without_range
+; CHECK-LABEL: @ne_with_range
+; CHECK-NEXT: %v1 = load i8* %0{{$}}
+; CHECK-NEXT: %v2 = load i8* %1{{$}}
+; CHECK-NEXT: %out = icmp ne i8 %v1, %v2
+; CHECK-NEXT: ret i1 %out
+  %v1 = load i8* %0, !range !0
+  %v2 = load i8* %1, !range !0
+  %out = icmp ne i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @eq_with_range(i8*, i8*) {
+; The range must be a merge of the ranges used in the two functions, the check
+; for the range being correct is at the end of the file
+; CHECK-LABEL: @eq_with_range
+; CHECK: %v1 = load i8* %0, !range !0
+; CHECK: %v2 = load i8* %1, !range !0
+; CHECK: %out = icmp eq i8 %v1, %v2
+; CHECK: ret i1 %out
+  %v1 = load i8* %0, !range !0
+  %v2 = load i8* %1, !range !0
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @ne_without_range(i8*, i8*) {
+; CHECK-LABEL: @ne_without_range
+; CHECK-NEXT: tail call i1 @ne_with_range
+; CHECK-NEXT: ret i1
+  %v1 = load i8* %0
+  %v2 = load i8* %1
+  %out = icmp ne i8 %v1, %v2
+  ret i1 %out
+}
+
+define i1 @eq_with_different_range(i8*, i8*) {
+; CHECK-LABEL: @eq_with_different_range
+; CHECK-NEXT: tail call i1 @eq_with_range
+; CHECK-NEXT: ret i1
+  %v1 = load i8* %0, !range !1
+  %v2 = load i8* %1, !range !1
+  %out = icmp eq i8 %v1, %v2
+  ret i1 %out
+}
+
+; The merged range for the @eq_* functions
+; CHECK: !0 = metadata !{i8 0, i8 2, i8 5, i8 7}
+!0 = metadata !{i8 0, i8 2}
+!1 = metadata !{i8 5, i8 7}