Index: lib/Transforms/InstCombine/InstructionCombining.cpp
===================================================================
--- lib/Transforms/InstCombine/InstructionCombining.cpp
+++ lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1453,8 +1453,13 @@
       }
     }
 
-    GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(Op1->clone());
+    // If not all GEPs are identical we'll have to create a new PHI node.
+    // Check that the old PHI node has only one use so that it will get
+    // removed.
+    if (DI != -1 && !PN->hasOneUse())
+      return nullptr;
 
+    GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(Op1->clone());
     if (DI == -1) {
       // All the GEPs feeding the PHI are identical. Clone one down into our
       // BB so that it can be merged with the current GEP.
Index: test/Transforms/InstCombine/gepphigep.ll
===================================================================
--- test/Transforms/InstCombine/gepphigep.ll
+++ test/Transforms/InstCombine/gepphigep.ll
@@ -134,3 +134,53 @@
 ; CHECK: getelementptr{{.*}}i64 1
 ; CHECK: exit:
 }
+
+@.str.4 = external unnamed_addr constant [100 x i8], align 1
+
+; Instcombine shouldn't add new PHI nodes while folding GEPs if that will leave
+; old PHI nodes behind as this is not clearly beneficial.
+; CHECK-LABEL: @test5(
+define void @test5(i16 *%idx, i8 **%in) #0 {
+entry:
+  %0 = load i8*, i8** %in
+  %incdec.ptr = getelementptr inbounds i8, i8* %0, i32 1
+  %1 = load i8, i8* %incdec.ptr, align 1
+  %cmp23 = icmp eq i8 %1, 54
+  br i1 %cmp23, label %while.cond, label %if.then.25
+
+if.then.25:
+  call void @g(i8* getelementptr inbounds ([100 x i8], [100 x i8]* @.str.4, i32 0, i32 0))
+  br label %while.cond
+
+while.cond:
+; CHECK-LABEL: while.cond
+; CHECK-NOT: phi i8* [ %0, %entry ], [ %Ptr, %while.body ], [ %0, %if.then.25 ]
+  %Ptr = phi i8* [ %incdec.ptr, %entry ], [ %incdec.ptr32, %while.body], [%incdec.ptr, %if.then.25 ]
+  %2 = load i8, i8* %Ptr
+  %and = and i8 %2, 64
+  %lnot = icmp eq i8 %and, 0
+  br i1 %lnot, label %while.body, label %while.cond.33
+
+while.body:
+  %incdec.ptr32 = getelementptr inbounds i8, i8* %Ptr, i32 1
+  br label %while.cond
+
+while.cond.33:
+  %incdec.ptr34 = getelementptr inbounds i8, i8* %Ptr, i32 1
+  br label %while.cond.57
+
+while.cond.57:
+  %3 = load i8, i8* %incdec.ptr34, align 1
+  %conv59 = zext i8 %3 to i32
+  %arrayidx61 = getelementptr inbounds i16, i16* %idx, i32 %conv59
+  %4 = load i16, i16* %arrayidx61, align 2
+  %and63 = and i16 %4, 2048
+  %tobool64 = icmp eq i16 %and63, 0
+  br i1 %tobool64, label %while.cond.73, label %while.cond.57
+
+while.cond.73:
+  br label %while.cond.73
+
+}
+
+declare void @g(i8*)