Index: lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- lib/Transforms/InstCombine/InstructionCombining.cpp
+++ lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1670,6 +1670,23 @@
     if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))
       return nullptr;
 
+    // Try to reassociate loop invariant GEP chains to enable LICM.
+    if (LI && Src->getNumOperands() == 2 && GEP.getNumOperands() == 2 &&
+        Src->hasOneUse()) {
+      if (Loop *L = LI->getLoopFor(GEP.getParent())) {
+        Value *GO1 = GEP.getOperand(1);
+        Value *SO1 = Src->getOperand(1);
+        // Reassociate the two GEPs if SO1 is variant in the loop and GO1 is
+        // invariant: this breaks the dependence between GEPs and allows LICM
+        // to hoist the invariant part out of the loop.
+        if (L->isLoopInvariant(GO1) && !L->isLoopInvariant(SO1)) {
+          Src->setOperand(1, GO1);
+          GEP.setOperand(1, SO1);
+          return &GEP;
+        }
+      }
+    }
+
     // Note that if our source is a gep chain itself then we wait for that
     // chain to be resolved before we perform this transformation.  This
     // avoids us creating a TON of code in some cases.
Index: test/Transforms/InstCombine/gep-combine-loop-invariant.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/gep-combine-loop-invariant.ll
@@ -0,0 +1,91 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -instcombine -S | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; Function Attrs: norecurse nounwind readonly uwtable
+define i32 @foo(i8* nocapture readnone %match, i32 %cur_match, i32 %best_len, i32 %scan_end, i32* nocapture readonly %prev, i32 %limit, i32 %chain_length, i8* nocapture readonly %win, i32 %wmask) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[IDX_EXT2:%.*]] = zext i32 [[CUR_MATCH:%.*]] to i64
+; CHECK-NEXT:    [[ADD_PTR4:%.*]] = getelementptr inbounds i8, i8* [[WIN:%.*]], i64 [[IDX_EXT2]]
+; CHECK-NEXT:    [[IDX_EXT1:%.*]] = zext i32 [[BEST_LEN:%.*]] to i64
+; CHECK-NEXT:    [[ADD_PTR25:%.*]] = getelementptr inbounds i8, i8* [[ADD_PTR4]], i64 [[IDX_EXT1]]
+; CHECK-NEXT:    [[ADD_PTR36:%.*]] = getelementptr inbounds i8, i8* [[ADD_PTR25]], i64 -1
+; CHECK-NEXT:    [[TMP0:%.*]] = bitcast i8* [[ADD_PTR36]] to i32*
+; CHECK-NEXT:    [[TMP1:%.*]] = load i32, i32* [[TMP0]], align 4
+; CHECK-NEXT:    [[CMP7:%.*]] = icmp eq i32 [[TMP1]], [[SCAN_END:%.*]]
+; CHECK-NEXT:    br i1 [[CMP7]], label [[DO_END:%.*]], label [[IF_THEN_LR_PH:%.*]]
+; CHECK:       if.then.lr.ph:
+; CHECK-NEXT:    br label [[IF_THEN:%.*]]
+; CHECK:       do.body:
+; CHECK-NEXT:    [[IDX_EXT:%.*]] = zext i32 [[TMP4:%.*]] to i64
+; CHECK-NEXT:    [[ADD_PTR:%.*]] = getelementptr inbounds i8, i8* [[WIN]], i64 [[IDX_EXT1]]
+; CHECK-NEXT:    [[ADD_PTR2:%.*]] = getelementptr inbounds i8, i8* [[ADD_PTR]], i64 -1
+; CHECK-NEXT:    [[ADD_PTR3:%.*]] = getelementptr inbounds i8, i8* [[ADD_PTR2]], i64 [[IDX_EXT]]
+; CHECK-NEXT:    [[TMP2:%.*]] = bitcast i8* [[ADD_PTR3]] to i32*
+; CHECK-NEXT:    [[TMP3:%.*]] = load i32, i32* [[TMP2]], align 4
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP3]], [[SCAN_END]]
+; CHECK-NEXT:    br i1 [[CMP]], label [[DO_END]], label [[IF_THEN]]
+; CHECK:       if.then:
+; CHECK-NEXT:    [[CUR_MATCH_ADDR_09:%.*]] = phi i32 [ [[CUR_MATCH]], [[IF_THEN_LR_PH]] ], [ [[TMP4]], [[DO_BODY:%.*]] ]
+; CHECK-NEXT:    [[CHAIN_LENGTH_ADDR_08:%.*]] = phi i32 [ [[CHAIN_LENGTH:%.*]], [[IF_THEN_LR_PH]] ], [ [[DEC:%.*]], [[DO_BODY]] ]
+; CHECK-NEXT:    [[AND:%.*]] = and i32 [[CUR_MATCH_ADDR_09]], [[WMASK:%.*]]
+; CHECK-NEXT:    [[IDXPROM:%.*]] = zext i32 [[AND]] to i64
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, i32* [[PREV:%.*]], i64 [[IDXPROM]]
+; CHECK-NEXT:    [[TMP4]] = load i32, i32* [[ARRAYIDX]], align 4
+; CHECK-NEXT:    [[CMP4:%.*]] = icmp ugt i32 [[TMP4]], [[LIMIT:%.*]]
+; CHECK-NEXT:    br i1 [[CMP4]], label [[LAND_LHS_TRUE:%.*]], label [[DO_END]]
+; CHECK:       land.lhs.true:
+; CHECK-NEXT:    [[DEC]] = add i32 [[CHAIN_LENGTH_ADDR_08]], -1
+; CHECK-NEXT:    [[CMP5:%.*]] = icmp eq i32 [[DEC]], 0
+; CHECK-NEXT:    br i1 [[CMP5]], label [[DO_END]], label [[DO_BODY]]
+; CHECK:       do.end:
+; CHECK-NEXT:    [[CONT_0:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ 0, [[IF_THEN]] ], [ 0, [[LAND_LHS_TRUE]] ], [ 1, [[DO_BODY]] ]
+; CHECK-NEXT:    ret i32 [[CONT_0]]
+;
+entry:
+  %idx.ext2 = zext i32 %cur_match to i64
+  %add.ptr4 = getelementptr inbounds i8, i8* %win, i64 %idx.ext2
+  %idx.ext1 = zext i32 %best_len to i64
+  %add.ptr25 = getelementptr inbounds i8, i8* %add.ptr4, i64 %idx.ext1
+  %add.ptr36 = getelementptr inbounds i8, i8* %add.ptr25, i64 -1
+  %0 = bitcast i8* %add.ptr36 to i32*
+  %1 = load i32, i32* %0, align 4
+  %cmp7 = icmp eq i32 %1, %scan_end
+  br i1 %cmp7, label %do.end, label %if.then.lr.ph
+
+if.then.lr.ph:                                    ; preds = %entry
+  br label %if.then
+
+do.body:                                          ; preds = %land.lhs.true
+  %chain_length.addr.0 = phi i32 [ %dec, %land.lhs.true ]
+  %cur_match.addr.0 = phi i32 [ %4, %land.lhs.true ]
+  %idx.ext = zext i32 %cur_match.addr.0 to i64
+  %add.ptr = getelementptr inbounds i8, i8* %win, i64 %idx.ext
+  %add.ptr2 = getelementptr inbounds i8, i8* %add.ptr, i64 %idx.ext1
+  %add.ptr3 = getelementptr inbounds i8, i8* %add.ptr2, i64 -1
+  %2 = bitcast i8* %add.ptr3 to i32*
+  %3 = load i32, i32* %2, align 4
+  %cmp = icmp eq i32 %3, %scan_end
+  br i1 %cmp, label %do.end, label %if.then
+
+if.then:                                          ; preds = %if.then.lr.ph, %do.body
+  %cur_match.addr.09 = phi i32 [ %cur_match, %if.then.lr.ph ], [ %cur_match.addr.0, %do.body ]
+  %chain_length.addr.08 = phi i32 [ %chain_length, %if.then.lr.ph ], [ %chain_length.addr.0, %do.body ]
+  %and = and i32 %cur_match.addr.09, %wmask
+  %idxprom = zext i32 %and to i64
+  %arrayidx = getelementptr inbounds i32, i32* %prev, i64 %idxprom
+  %4 = load i32, i32* %arrayidx, align 4
+  %cmp4 = icmp ugt i32 %4, %limit
+  br i1 %cmp4, label %land.lhs.true, label %do.end
+
+land.lhs.true:                                    ; preds = %if.then
+  %dec = add i32 %chain_length.addr.08, -1
+  %cmp5 = icmp eq i32 %dec, 0
+  br i1 %cmp5, label %do.end, label %do.body
+
+do.end:                                           ; preds = %do.body, %land.lhs.true, %if.then, %entry
+  %cont.0 = phi i32 [ 1, %entry ], [ 0, %if.then ], [ 0, %land.lhs.true ], [ 1, %do.body ]
+  ret i32 %cont.0
+}
Index: test/Transforms/LoopVectorize/consecutive-ptr-uniforms.ll
===================================================================
--- test/Transforms/LoopVectorize/consecutive-ptr-uniforms.ll
+++ test/Transforms/LoopVectorize/consecutive-ptr-uniforms.ll
@@ -48,8 +48,8 @@
 ; CHECK:       %index = phi i64 [ 0, %vector.ph ], [ %index.next, %vector.body ]
 ; CHECK:       %offset.idx = sub i64 %n, %index
 ; CHECK-NOT:   getelementptr
-; CHECK:       %[[G0:.+]] = getelementptr inbounds i32, i32* %a, i64 %offset.idx
-; CHECK:       getelementptr i32, i32* %[[G0]], i64 -3
+; CHECK:       %[[G0:.+]] = getelementptr inbounds i32, i32* %a, i64 -3
+; CHECK:       getelementptr i32, i32* %[[G0]], i64 %offset.idx
 ; CHECK-NOT:   getelementptr
 ; CHECK:       br i1 {{.*}}, label %middle.block, label %vector.body
 ;