Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -11996,7 +11996,7 @@
 
 ::
 
-      declare void @llvm.invariant.end.p0i8({}* <start>, i64 <size>, i8* nocapture <ptr>)
+      declare void @llvm.invariant.end.p0i8({}* readnone <start>, i64 <size>, i8* nocapture <ptr>)
 
 Overview:
 """""""""
Index: include/llvm/IR/Intrinsics.td
===================================================================
--- include/llvm/IR/Intrinsics.td
+++ include/llvm/IR/Intrinsics.td
@@ -576,7 +576,8 @@
 def int_invariant_end   : Intrinsic<[],
                                     [llvm_descriptor_ty, llvm_i64_ty,
                                      llvm_anyptr_ty],
-                                    [IntrArgMemOnly, NoCapture<2>]>;
+                                    [IntrArgMemOnly, NoCapture<2>,
+                                     ReadNone<0>]>;
 
 def int_invariant_group_barrier : Intrinsic<[llvm_ptr_ty], 
                                             [llvm_ptr_ty], 
Index: lib/Analysis/MemoryLocation.cpp
===================================================================
--- lib/Analysis/MemoryLocation.cpp
+++ lib/Analysis/MemoryLocation.cpp
@@ -121,9 +121,16 @@
           Arg, cast<ConstantInt>(II->getArgOperand(0))->getZExtValue(), AATags);
 
     case Intrinsic::invariant_end:
-      assert(ArgIdx == 2 && "Invalid argument index");
-      return MemoryLocation(
-          Arg, cast<ConstantInt>(II->getArgOperand(1))->getZExtValue(), AATags);
+      if (ArgIdx == 0)
+        // Technically, this is a token gotten from a previous invariant_start
+        // and not a true pointer, so return a dummy MemoryLocation.
+        return MemoryLocation(Arg, 0);
+      else if (ArgIdx == 2)
+        return MemoryLocation(
+            Arg, cast<ConstantInt>(II->getArgOperand(1))->getZExtValue(),
+            AATags);
+      // For all other argument indices, this call is invalid.
+      assert(false && "Invalid argument index");
 
     case Intrinsic::arm_neon_vld1:
       assert(ArgIdx == 0 && "Invalid argument index");
Index: test/Analysis/BasicAA/getforargument-crash.ll
===================================================================
--- /dev/null
+++ test/Analysis/BasicAA/getforargument-crash.ll
@@ -0,0 +1,27 @@
+; RUN: opt -disable-output 2>&1 -basicaa -aa-eval -print-all-alias-modref-info \
+; RUN:      %s 2>&1 | FileCheck %s
+
+declare {}* @llvm.invariant.start(i64, i8* nocapture) nounwind readonly
+declare void @llvm.invariant.end({}* readnone, i64, i8* nocapture) nounwind
+declare void @f({}*)
+
+; Previously caused getModRefInfo to retrieve a MemoryLocation for an invalid
+; argument to the intrinsic.
+define void @tests_invariant_start_end() {
+; CHECK-LABEL: tests_invariant_start_end
+  %a = alloca i8
+  %i = call {}* @llvm.invariant.start(i64 1, i8* %a)
+  call void @llvm.invariant.end({}* %i, i64 1, i8* %a)
+  ret void
+}
+
+; Prove that invariant.end's first argument is readnone.
+define void @it_really_is_readnone({}* %g) {
+; CHECK-LABEL: it_really_is_readnone
+  %a = alloca i8
+  %i = call {}* @llvm.invariant.start(i64 1, i8* %a)
+  call void @f({}* %g)
+  call void @llvm.invariant.end({}* %i, i64 1, i8* %a)
+; CHECK: NoModRef:   call void @f({}* %g) <->   call void @llvm.invariant.end.p0i8({}* %1, i64 1, i8* %a)
+  ret void
+}