Index: llvm/lib/Analysis/MemoryLocation.cpp
===================================================================
--- llvm/lib/Analysis/MemoryLocation.cpp
+++ llvm/lib/Analysis/MemoryLocation.cpp
@@ -222,9 +222,10 @@
         return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
                               AATags);
       break;
+    case LibFunc_bcmp:
     case LibFunc_memcmp:
       assert((ArgIdx == 0 || ArgIdx == 1) &&
-             "Invalid argument index for memcmp");
+             "Invalid argument index for memcmp/bcmp");
       if (const ConstantInt *LenCI =
               dyn_cast<ConstantInt>(Call->getArgOperand(2)))
         return MemoryLocation(Arg, LocationSize::precise(LenCI->getZExtValue()),
Index: llvm/test/Transforms/DeadStoreElimination/MSSA/libcalls.ll
===================================================================
--- llvm/test/Transforms/DeadStoreElimination/MSSA/libcalls.ll
+++ llvm/test/Transforms/DeadStoreElimination/MSSA/libcalls.ll
@@ -130,3 +130,64 @@
   %res = call i32 @memcmp(i8* nonnull %foo, i8* nonnull %stack.ptr, i64 %n)
   ret i32 %res
 }
+
+
+declare i32 @bcmp(i8*, i8*, i64)
+
+define i1 @test_bcmp_const_size(i8* noalias %foo) {
+; CHECK-LABEL: @test_bcmp_const_size(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[STACK:%.*]] = alloca [10 x i8], align 1
+; CHECK-NEXT:    [[STACK_PTR:%.*]] = bitcast [10 x i8]* [[STACK]] to i8*
+; CHECK-NEXT:    store i8 49, i8* [[STACK_PTR]], align 1
+; CHECK-NEXT:    [[GEP_1:%.*]] = getelementptr i8, i8* [[STACK_PTR]], i64 1
+; CHECK-NEXT:    store i8 50, i8* [[GEP_1]], align 1
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @bcmp(i8* nonnull dereferenceable(2) [[FOO:%.*]], i8* nonnull dereferenceable(2) [[STACK_PTR]], i64 2)
+; CHECK-NEXT:    [[RES:%.*]] = icmp eq i32 [[CALL]], 0
+; CHECK-NEXT:    ret i1 [[RES]]
+;
+entry:
+  %stack = alloca [10 x i8]
+  %stack.ptr = bitcast [10 x i8]* %stack to i8*
+  store i8 49, i8* %stack.ptr, align 1
+  %gep.1 = getelementptr i8, i8* %stack.ptr, i64 1
+  store i8 50, i8* %gep.1, align 1
+  %gep.2 = getelementptr i8, i8* %stack.ptr, i64 2
+  store i8 51, i8* %gep.2, align 1
+  %gep.3 = getelementptr i8, i8* %stack.ptr, i64 3
+  store i8 52, i8* %gep.3, align 1
+  %call = call i32 @bcmp(i8* nonnull dereferenceable(2) %foo, i8* nonnull dereferenceable(2) %stack.ptr, i64 2)
+  %res = icmp eq i32 %call, 0
+  ret i1 %res
+}
+
+define i1 @test_bcmp_variable_size(i8* noalias %foo, i64 %n) {
+; CHECK-LABEL: @test_bcmp_variable_size(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[STACK:%.*]] = alloca [10 x i8], align 1
+; CHECK-NEXT:    [[STACK_PTR:%.*]] = bitcast [10 x i8]* [[STACK]] to i8*
+; CHECK-NEXT:    store i8 49, i8* [[STACK_PTR]], align 1
+; CHECK-NEXT:    [[GEP_1:%.*]] = getelementptr i8, i8* [[STACK_PTR]], i64 1
+; CHECK-NEXT:    store i8 50, i8* [[GEP_1]], align 1
+; CHECK-NEXT:    [[GEP_2:%.*]] = getelementptr i8, i8* [[STACK_PTR]], i64 2
+; CHECK-NEXT:    store i8 51, i8* [[GEP_2]], align 1
+; CHECK-NEXT:    [[GEP_3:%.*]] = getelementptr i8, i8* [[STACK_PTR]], i64 3
+; CHECK-NEXT:    store i8 52, i8* [[GEP_3]], align 1
+; CHECK-NEXT:    [[CALL:%.*]] = call i32 @bcmp(i8* nonnull [[FOO:%.*]], i8* nonnull [[STACK_PTR]], i64 [[N:%.*]])
+; CHECK-NEXT:    [[RES:%.*]] = icmp eq i32 [[CALL]], 0
+; CHECK-NEXT:    ret i1 [[RES]]
+;
+entry:
+  %stack = alloca [10 x i8]
+  %stack.ptr = bitcast [10 x i8]* %stack to i8*
+  store i8 49, i8* %stack.ptr, align 1
+  %gep.1 = getelementptr i8, i8* %stack.ptr, i64 1
+  store i8 50, i8* %gep.1, align 1
+  %gep.2 = getelementptr i8, i8* %stack.ptr, i64 2
+  store i8 51, i8* %gep.2, align 1
+  %gep.3 = getelementptr i8, i8* %stack.ptr, i64 3
+  store i8 52, i8* %gep.3, align 1
+  %call = call i32 @bcmp(i8* nonnull %foo, i8* nonnull %stack.ptr, i64 %n)
+  %res = icmp eq i32 %call, 0
+  ret i1 %res
+}