Index: llvm/trunk/lib/Transforms/InstCombine/InstCombinePHI.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombinePHI.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombinePHI.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Transforms/Utils/Local.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "instcombine"
@@ -349,24 +350,37 @@
 
   Value *InVal = FirstLI->getOperand(0);
   NewPN->addIncoming(InVal, PN.getIncomingBlock(0));
+  LoadInst *NewLI = new LoadInst(NewPN, "", isVolatile, LoadAlignment);
 
-  // Add all operands to the new PHI.
+  unsigned KnownIDs[] = {
+    LLVMContext::MD_tbaa,
+    LLVMContext::MD_range,
+    LLVMContext::MD_invariant_load,
+    LLVMContext::MD_alias_scope,
+    LLVMContext::MD_noalias,
+    LLVMContext::MD_nonnull
+  };
+
+  for (unsigned ID : KnownIDs)
+    NewLI->setMetadata(ID, FirstLI->getMetadata(ID));
+
+  // Add all operands to the new PHI and combine TBAA metadata.
   for (unsigned i = 1, e = PN.getNumIncomingValues(); i != e; ++i) {
-    Value *NewInVal = cast<LoadInst>(PN.getIncomingValue(i))->getOperand(0);
+    LoadInst *LI = cast<LoadInst>(PN.getIncomingValue(i));
+    combineMetadata(NewLI, LI, KnownIDs);
+    Value *NewInVal = LI->getOperand(0);
     if (NewInVal != InVal)
       InVal = nullptr;
     NewPN->addIncoming(NewInVal, PN.getIncomingBlock(i));
   }
 
-  Value *PhiVal;
   if (InVal) {
     // The new PHI unions all of the same values together.  This is really
     // common, so we handle it intelligently here for compile-time speed.
-    PhiVal = InVal;
+    NewLI->setOperand(0, InVal);
     delete NewPN;
   } else {
     InsertNewInstBefore(NewPN, PN);
-    PhiVal = NewPN;
   }
 
   // If this was a volatile load that we are merging, make sure to loop through
@@ -376,7 +390,6 @@
     for (Value *IncValue : PN.incoming_values())
       cast<LoadInst>(IncValue)->setVolatile(false);
 
-  LoadInst *NewLI = new LoadInst(PhiVal, "", isVolatile, LoadAlignment);
   NewLI->setDebugLoc(FirstLI->getDebugLoc());
   return NewLI;
 }
Index: llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll
+++ llvm/trunk/test/Transforms/InstCombine/fold-phi-load-metadata.ll
@@ -0,0 +1,69 @@
+; RUN: opt -instcombine -S < %s | FileCheck %s
+
+@g1 = common global i32* null, align 8
+
+%struct.S1 = type { i32, float }
+%struct.S2 = type { float, i32 }
+
+; Check that instcombine preserves metadata when it merges two loads.
+;
+; CHECK: return:
+; CHECK: load i32*, i32** %{{[a-z0-9.]+}}, align 8, !nonnull ![[EMPTYNODE:[0-9]+]]
+; CHECK: load i32, i32* %{{[a-z0-9.]+}}, align 4, !tbaa ![[TBAA:[0-9]+]], !range ![[RANGE:[0-9]+]], !invariant.load ![[EMPTYNODE:[0-9]+]], !alias.scope ![[ALIAS_SCOPE:[0-9]+]], !noalias ![[NOALIAS:[0-9]+]]
+
+; Function Attrs: nounwind ssp uwtable
+define i32 @phi_load_metadata(%struct.S1* %s1, %struct.S2* %s2, i32 %c, i32** %x0, i32 **%x1) #0 {
+entry:
+  %tobool = icmp eq i32 %c, 0
+  br i1 %tobool, label %if.end, label %if.then
+
+if.then:                                          ; preds = %entry
+  %i = getelementptr inbounds %struct.S2, %struct.S2* %s2, i64 0, i32 1
+  %val = load i32, i32* %i, align 4, !tbaa !0, !alias.scope !13, !noalias !14, !invariant.load !17, !range !18
+  %p0 = load i32*, i32** %x0, align 8, !nonnull !17
+  br label %return
+
+if.end:                                           ; preds = %entry
+  %i2 = getelementptr inbounds %struct.S1, %struct.S1* %s1, i64 0, i32 0
+  %val2 = load i32, i32* %i2, align 4, !tbaa !2, !alias.scope !15, !noalias !16, !invariant.load !17, !range !19
+  %p1 = load i32*, i32** %x1, align 8, !nonnull !17
+  br label %return
+
+return:                                           ; preds = %if.end, %if.then
+  %retval = phi i32 [ %val, %if.then ], [ %val2, %if.end ]
+  %pval = phi i32* [ %p0, %if.then ], [ %p1, %if.end ]
+  store i32* %pval, i32** @g1, align 8
+  ret i32 %retval
+}
+
+; CHECK: ![[EMPTYNODE]] = !{}
+; CHECK: ![[TBAA]] = !{![[TAG1:[0-9]+]], ![[TAG1]], i64 0}
+; CHECK: ![[TAG1]] = !{!"int", !{{[0-9]+}}, i64 0}
+; CHECK: ![[RANGE]] = !{i32 10, i32 25}
+; CHECK: ![[ALIAS_SCOPE]] = !{![[SCOPE0:[0-9]+]], ![[SCOPE1:[0-9]+]], ![[SCOPE2:[0-9]+]]}
+; CHECK: ![[SCOPE0]] = distinct !{![[SCOPE0]], !{{[0-9]+}}, !"scope0"}
+; CHECK: ![[SCOPE1]] = distinct !{![[SCOPE1]], !{{[0-9]+}}, !"scope1"}
+; CHECK: ![[SCOPE2]] = distinct !{![[SCOPE2]], !{{[0-9]+}}, !"scope2"}
+; CHECK: ![[NOALIAS]] = !{![[SCOPE3:[0-9]+]]}
+; CHECK: ![[SCOPE3]] = distinct !{![[SCOPE3]], !{{[0-9]+}}, !"scope3"}
+
+!0 = !{!1, !4, i64 4}
+!1 = !{!"", !7, i64 0, !4, i64 4}
+!2 = !{!3, !4, i64 0}
+!3 = !{!"", !4, i64 0, !7, i64 4}
+!4 = !{!"int", !5, i64 0}
+!5 = !{!"omnipotent char", !6, i64 0}
+!6 = !{!"Simple C/C++ TBAA"}
+!7 = !{!"float", !5, i64 0}
+!8 = !{!8, !"some domain"}
+!9 = !{!9, !8, !"scope0"}
+!10 = !{!10, !8, !"scope1"}
+!11 = !{!11, !8, !"scope2"}
+!12 = !{!12, !8, !"scope3"}
+!13 = !{!9, !10}
+!14 = !{!11, !12}
+!15 = !{!9, !11}
+!16 = !{!10, !12}
+!17 = !{}
+!18 = !{i32 10, i32 20}
+!19 = !{i32 15, i32 25}