diff --git a/Cargo.lock b/Cargo.lock
index 59505ff7ed7..3c49d6f4d2c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3082,6 +3082,7 @@ dependencies = [
  "rustc_data_structures",
  "rustc_errors",
  "rustc_fs_util",
+ "rustc_index",
  "rustc_macros",
  "rustc_target",
  "scoped-tls",
@@ -3341,6 +3342,7 @@ dependencies = [
 name = "rustc_codegen_llvm"
 version = "0.0.0"
 dependencies = [
+ "rustc_index",
  "rustc_llvm",
 ]
 
@@ -3362,6 +3364,7 @@ dependencies = [
  "rustc_errors",
  "rustc_fs_util",
  "rustc_incremental",
+ "rustc_index",
  "rustc_target",
  "serialize",
  "syntax",
@@ -3561,6 +3564,7 @@ dependencies = [
  "rustc",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_index",
  "rustc_target",
  "serialize",
  "smallvec",
@@ -3583,6 +3587,7 @@ dependencies = [
  "rustc_apfloat",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_index",
  "rustc_lexer",
  "rustc_target",
  "serialize",
@@ -4246,6 +4251,7 @@ dependencies = [
  "log",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_index",
  "rustc_lexer",
  "rustc_target",
  "scoped-tls",
diff --git a/src/librustc/Cargo.toml b/src/librustc/Cargo.toml
index 0834faf1324..a7c94d057dc 100644
--- a/src/librustc/Cargo.toml
+++ b/src/librustc/Cargo.toml
@@ -25,6 +25,7 @@ rustc_apfloat = { path = "../librustc_apfloat" }
 rustc_target = { path = "../librustc_target" }
 rustc_macros = { path = "../librustc_macros" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_index = { path = "../librustc_index" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 syntax = { path = "../libsyntax" }
diff --git a/src/librustc/arena.rs b/src/librustc/arena.rs
index 5d06f62f446..b922910c4d7 100644
--- a/src/librustc/arena.rs
+++ b/src/librustc/arena.rs
@@ -45,7 +45,7 @@ macro_rules! arena_types {
             [decode] specialization_graph: rustc::traits::specialization_graph::Graph,
             [] region_scope_tree: rustc::middle::region::ScopeTree,
             [] item_local_set: rustc::util::nodemap::ItemLocalSet,
-            [decode] mir_const_qualif: rustc_data_structures::bit_set::BitSet<rustc::mir::Local>,
+            [decode] mir_const_qualif: rustc_index::bit_set::BitSet<rustc::mir::Local>,
             [] trait_impls_of: rustc::ty::trait_def::TraitImpls,
             [] dropck_outlives:
                 rustc::infer::canonical::Canonical<'tcx,
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index 5e12c4dfe75..00d7400a651 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -20,7 +20,7 @@ use crate::ty::{
 };
 
 use polonius_engine::Atom;
-use rustc_data_structures::bit_set::BitMatrix;
+use rustc_index::bit_set::BitMatrix;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::graph::dominators::{dominators, Dominators};
 use rustc_data_structures::graph::{self, GraphPredecessors, GraphSuccessors};
diff --git a/src/librustc/mir/traversal.rs b/src/librustc/mir/traversal.rs
index 1416a5f0a6e..f129dd3abef 100644
--- a/src/librustc/mir/traversal.rs
+++ b/src/librustc/mir/traversal.rs
@@ -1,4 +1,4 @@
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 
 use super::*;
 
diff --git a/src/librustc/traits/select.rs b/src/librustc/traits/select.rs
index e1ca9a16d96..ef79417c6f0 100644
--- a/src/librustc/traits/select.rs
+++ b/src/librustc/traits/select.rs
@@ -40,7 +40,7 @@ use crate::ty::subst::{Subst, SubstsRef};
 use crate::ty::{self, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable};
 
 use crate::hir;
-use rustc_data_structures::bit_set::GrowableBitSet;
+use rustc_index::bit_set::GrowableBitSet;
 use rustc_data_structures::sync::Lock;
 use rustc_target::spec::abi::Abi;
 use syntax::attr;
diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs
index 6ab4f4c6112..eb2e1de7787 100644
--- a/src/librustc/ty/layout.rs
+++ b/src/librustc/ty/layout.rs
@@ -17,7 +17,7 @@ use crate::ich::StableHashingContext;
 use crate::mir::{GeneratorLayout, GeneratorSavedLocal};
 use crate::ty::GeneratorSubsts;
 use crate::ty::subst::Subst;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{IndexVec, Idx};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 
diff --git a/src/librustc/ty/query/mod.rs b/src/librustc/ty/query/mod.rs
index f559cde4b03..e5c3a8402a7 100644
--- a/src/librustc/ty/query/mod.rs
+++ b/src/librustc/ty/query/mod.rs
@@ -38,11 +38,11 @@ use crate::ty::steal::Steal;
 use crate::ty::util::NeedsDrop;
 use crate::ty::subst::SubstsRef;
 use crate::util::nodemap::{DefIdSet, DefIdMap, ItemLocalSet};
-use crate::util::common::{ErrorReported};
+use crate::util::common::ErrorReported;
 use crate::util::profiling::ProfileCategory::*;
 
 use rustc_data_structures::svh::Svh;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_data_structures::fx::{FxIndexMap, FxHashMap, FxHashSet};
 use rustc_data_structures::stable_hasher::StableVec;
diff --git a/src/librustc_codegen_llvm/Cargo.toml b/src/librustc_codegen_llvm/Cargo.toml
index 98efa6a5804..540ab2a352a 100644
--- a/src/librustc_codegen_llvm/Cargo.toml
+++ b/src/librustc_codegen_llvm/Cargo.toml
@@ -12,6 +12,7 @@ test = false
 
 [dependencies]
 rustc_llvm = { path = "../librustc_llvm" }
+rustc_index = { path = "../librustc_index" }
 
 [features]
 # This is used to convince Cargo to separately cache builds of `rustc_codegen_llvm`
diff --git a/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs b/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
index 8b3ed5b0c62..45af55a7be7 100644
--- a/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
+++ b/src/librustc_codegen_llvm/debuginfo/create_scope_map.rs
@@ -11,7 +11,7 @@ use libc::c_uint;
 
 use syntax_pos::Pos;
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 
 use syntax_pos::BytePos;
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index 2e3666e6096..c7d09a423d5 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -29,4 +29,5 @@ rustc_data_structures = { path = "../librustc_data_structures"}
 rustc_errors = { path = "../librustc_errors" }
 rustc_fs_util = { path = "../librustc_fs_util" }
 rustc_incremental = { path = "../librustc_incremental" }
+rustc_index = { path = "../librustc_index" }
 rustc_target = { path = "../librustc_target" }
diff --git a/src/librustc_codegen_ssa/mir/analyze.rs b/src/librustc_codegen_ssa/mir/analyze.rs
index 05896523863..9dc3d956aaf 100644
--- a/src/librustc_codegen_ssa/mir/analyze.rs
+++ b/src/librustc_codegen_ssa/mir/analyze.rs
@@ -1,7 +1,7 @@
 //! An analysis to determine which locals require allocas and
 //! which do not.
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc::mir::{self, Location, TerminatorKind};
diff --git a/src/librustc_codegen_ssa/mir/mod.rs b/src/librustc_codegen_ssa/mir/mod.rs
index 4f3a8bdb540..7cf8a69cee3 100644
--- a/src/librustc_codegen_ssa/mir/mod.rs
+++ b/src/librustc_codegen_ssa/mir/mod.rs
@@ -13,7 +13,7 @@ use syntax::symbol::kw;
 
 use std::iter;
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::IndexVec;
 
 use self::analyze::CleanupKind;
diff --git a/src/librustc_data_structures/graph/implementation/mod.rs b/src/librustc_data_structures/graph/implementation/mod.rs
index d2699004c81..052a09c0774 100644
--- a/src/librustc_data_structures/graph/implementation/mod.rs
+++ b/src/librustc_data_structures/graph/implementation/mod.rs
@@ -20,7 +20,7 @@
 //! the field `next_edge`). Each of those fields is an array that should
 //! be indexed by the direction (see the type `Direction`).
 
-use crate::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use crate::snapshot_vec::{SnapshotVec, SnapshotVecDelegate};
 use std::fmt::Debug;
 use std::usize;
diff --git a/src/librustc_data_structures/graph/iterate/mod.rs b/src/librustc_data_structures/graph/iterate/mod.rs
index cbf6a0a3c03..999c5df7b86 100644
--- a/src/librustc_data_structures/graph/iterate/mod.rs
+++ b/src/librustc_data_structures/graph/iterate/mod.rs
@@ -1,6 +1,6 @@
 use super::super::indexed_vec::IndexVec;
 use super::{DirectedGraph, WithNumNodes, WithSuccessors, WithStartNode};
-use crate::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 
 #[cfg(test)]
 mod tests;
diff --git a/src/librustc_data_structures/lib.rs b/src/librustc_data_structures/lib.rs
index e28ee48201c..6a4602da36d 100644
--- a/src/librustc_data_structures/lib.rs
+++ b/src/librustc_data_structures/lib.rs
@@ -37,7 +37,7 @@ extern crate libc;
 extern crate cfg_if;
 
 pub use rustc_serialize::hex::ToHex;
-pub use rustc_index::{bit_set, indexed_vec, newtype_index};
+pub use rustc_index::{indexed_vec, newtype_index};
 
 #[inline(never)]
 #[cold]
diff --git a/src/librustc_data_structures/stable_hasher.rs b/src/librustc_data_structures/stable_hasher.rs
index 53dff794ff0..7f17a1aed62 100644
--- a/src/librustc_data_structures/stable_hasher.rs
+++ b/src/librustc_data_structures/stable_hasher.rs
@@ -3,7 +3,7 @@ use std::mem;
 use smallvec::SmallVec;
 use crate::sip128::SipHasher128;
 use crate::indexed_vec;
-use crate::bit_set;
+use rustc_index::bit_set;
 
 /// When hashing something that ends up affecting properties like symbol names,
 /// we want these symbol names to be calculated independently of other factors
diff --git a/src/librustc_data_structures/transitive_relation.rs b/src/librustc_data_structures/transitive_relation.rs
index 9c5447f3f5a..f0a9c3afc68 100644
--- a/src/librustc_data_structures/transitive_relation.rs
+++ b/src/librustc_data_structures/transitive_relation.rs
@@ -1,4 +1,4 @@
-use crate::bit_set::BitMatrix;
+use rustc_index::bit_set::BitMatrix;
 use crate::fx::FxHashMap;
 use crate::stable_hasher::{HashStable, StableHasher};
 use crate::sync::Lock;
diff --git a/src/librustc_data_structures/work_queue.rs b/src/librustc_data_structures/work_queue.rs
index 193025aafad..2c0e2261fee 100644
--- a/src/librustc_data_structures/work_queue.rs
+++ b/src/librustc_data_structures/work_queue.rs
@@ -1,4 +1,4 @@
-use crate::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use crate::indexed_vec::Idx;
 use std::collections::VecDeque;
 
diff --git a/src/librustc_index/lib.rs b/src/librustc_index/lib.rs
index d70f51aec01..5d7e0d82e78 100644
--- a/src/librustc_index/lib.rs
+++ b/src/librustc_index/lib.rs
@@ -1,5 +1,6 @@
 #![feature(allow_internal_unstable)]
 #![feature(unboxed_closures)]
+#![feature(test)]
 #![feature(fn_traits)]
 
 pub mod indexed_vec;
diff --git a/src/librustc_metadata/Cargo.toml b/src/librustc_metadata/Cargo.toml
index 5ff60a9267b..032470e1400 100644
--- a/src/librustc_metadata/Cargo.toml
+++ b/src/librustc_metadata/Cargo.toml
@@ -18,6 +18,7 @@ rustc = { path = "../librustc" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_target = { path = "../librustc_target" }
+rustc_index = { path = "../librustc_index" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
 stable_deref_trait = "1.0.0"
 syntax = { path = "../libsyntax" }
diff --git a/src/librustc_metadata/cstore_impl.rs b/src/librustc_metadata/cstore_impl.rs
index 83182df31cf..edb6f594fdd 100644
--- a/src/librustc_metadata/cstore_impl.rs
+++ b/src/librustc_metadata/cstore_impl.rs
@@ -35,7 +35,7 @@ use syntax::parse::source_file_to_stream;
 use syntax::parse::parser::emit_unclosed_delims;
 use syntax::symbol::Symbol;
 use syntax_pos::{Span, FileName};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 
 macro_rules! provide {
     (<$lt:tt> $tcx:ident, $def_id:ident, $other:ident, $cdata:ident,
diff --git a/src/librustc_mir/Cargo.toml b/src/librustc_mir/Cargo.toml
index f296753a030..f0cdcf2136b 100644
--- a/src/librustc_mir/Cargo.toml
+++ b/src/librustc_mir/Cargo.toml
@@ -19,6 +19,7 @@ polonius-engine  = "0.10.0"
 rustc = { path = "../librustc" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_index = { path = "../librustc_index" }
 rustc_errors = { path = "../librustc_errors" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_serialize = { path = "../libserialize", package = "serialize" }
diff --git a/src/librustc_mir/borrow_check/borrow_set.rs b/src/librustc_mir/borrow_check/borrow_set.rs
index db19cbc3175..3dcd1f56209 100644
--- a/src/librustc_mir/borrow_check/borrow_set.rs
+++ b/src/librustc_mir/borrow_check/borrow_set.rs
@@ -9,7 +9,7 @@ use rustc::mir::{self, Location, Body, Local};
 use rustc::ty::{RegionVid, TyCtxt};
 use rustc::util::nodemap::{FxHashMap, FxHashSet};
 use rustc_data_structures::indexed_vec::IndexVec;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use std::fmt;
 use std::ops::Index;
 
diff --git a/src/librustc_mir/borrow_check/flows.rs b/src/librustc_mir/borrow_check/flows.rs
index 1f17ab69f66..ce5d2a14bd1 100644
--- a/src/librustc_mir/borrow_check/flows.rs
+++ b/src/librustc_mir/borrow_check/flows.rs
@@ -5,7 +5,7 @@
 
 use rustc::mir::{BasicBlock, Local, Location};
 use rustc::ty::RegionVid;
-use rustc_data_structures::bit_set::BitIter;
+use rustc_index::bit_set::BitIter;
 
 use crate::borrow_check::location::LocationIndex;
 
diff --git a/src/librustc_mir/borrow_check/mod.rs b/src/librustc_mir/borrow_check/mod.rs
index cf80a1bc643..b9009ac5a51 100644
--- a/src/librustc_mir/borrow_check/mod.rs
+++ b/src/librustc_mir/borrow_check/mod.rs
@@ -18,7 +18,7 @@ use rustc::ty::query::Providers;
 use rustc::ty::{self, TyCtxt};
 
 use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::dominators::Dominators;
 use rustc_data_structures::indexed_vec::IndexVec;
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
index 78e7943598d..030839cdb7e 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/mod.rs
@@ -27,7 +27,7 @@ use rustc::mir::{
 use rustc::ty::{self, subst::SubstsRef, RegionVid, Ty, TyCtxt, TypeFoldable};
 use rustc::util::common::ErrorReported;
 use rustc_data_structures::binary_search_util;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_data_structures::graph::WithSuccessors;
 use rustc_data_structures::graph::scc::Sccs;
diff --git a/src/librustc_mir/borrow_check/nll/region_infer/values.rs b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
index 6f9f5707935..4a56af09d88 100644
--- a/src/librustc_mir/borrow_check/nll/region_infer/values.rs
+++ b/src/librustc_mir/borrow_check/nll/region_infer/values.rs
@@ -1,6 +1,6 @@
 use rustc::mir::{BasicBlock, Location, Body};
 use rustc::ty::{self, RegionVid};
-use rustc_data_structures::bit_set::{HybridBitSet, SparseBitMatrix};
+use rustc_index::bit_set::{HybridBitSet, SparseBitMatrix};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::indexed_vec::Idx;
 use rustc_data_structures::indexed_vec::IndexVec;
diff --git a/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs b/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
index 9b55881cb1b..36482a7b135 100644
--- a/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
+++ b/src/librustc_mir/borrow_check/nll/type_check/liveness/trace.rs
@@ -12,7 +12,7 @@ use rustc::traits::query::dropck_outlives::DropckOutlivesResult;
 use rustc::traits::query::type_op::outlives::DropckOutlives;
 use rustc::traits::query::type_op::TypeOp;
 use rustc::ty::{Ty, TypeFoldable};
-use rustc_data_structures::bit_set::HybridBitSet;
+use rustc_index::bit_set::HybridBitSet;
 use rustc_data_structures::fx::FxHashMap;
 use std::rc::Rc;
 
diff --git a/src/librustc_mir/build/matches/mod.rs b/src/librustc_mir/build/matches/mod.rs
index 8db06aa375e..861de07c612 100644
--- a/src/librustc_mir/build/matches/mod.rs
+++ b/src/librustc_mir/build/matches/mod.rs
@@ -15,7 +15,7 @@ use rustc::mir::*;
 use rustc::middle::region;
 use rustc::ty::{self, CanonicalUserTypeAnnotation, Ty};
 use rustc::ty::layout::VariantIdx;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use syntax::ast::Name;
 use syntax_pos::Span;
diff --git a/src/librustc_mir/build/matches/test.rs b/src/librustc_mir/build/matches/test.rs
index d8bb0b4f6cc..a04c989e6e0 100644
--- a/src/librustc_mir/build/matches/test.rs
+++ b/src/librustc_mir/build/matches/test.rs
@@ -9,9 +9,9 @@ use crate::build::Builder;
 use crate::build::matches::{Candidate, MatchPair, Test, TestKind};
 use crate::hair::*;
 use crate::hair::pattern::compare_const_vals;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::fx::FxHashMap;
-use rustc::ty::{self, Ty, adjustment::{PointerCast}};
+use rustc::ty::{self, Ty, adjustment::PointerCast};
 use rustc::ty::util::IntTypeExt;
 use rustc::ty::layout::VariantIdx;
 use rustc::mir::*;
diff --git a/src/librustc_mir/dataflow/at_location.rs b/src/librustc_mir/dataflow/at_location.rs
index f0014602e2d..e0ca1053523 100644
--- a/src/librustc_mir/dataflow/at_location.rs
+++ b/src/librustc_mir/dataflow/at_location.rs
@@ -2,7 +2,7 @@
 //! locations.
 
 use rustc::mir::{BasicBlock, Location};
-use rustc_data_structures::bit_set::{BitIter, BitSet, HybridBitSet};
+use rustc_index::bit_set::{BitIter, BitSet, HybridBitSet};
 
 use crate::dataflow::{BitDenotation, DataflowResults, GenKillSet};
 use crate::dataflow::move_paths::{HasMoveData, MovePathIndex};
diff --git a/src/librustc_mir/dataflow/generic.rs b/src/librustc_mir/dataflow/generic.rs
index 886044c0692..10d0627a9fb 100644
--- a/src/librustc_mir/dataflow/generic.rs
+++ b/src/librustc_mir/dataflow/generic.rs
@@ -20,7 +20,7 @@ use std::cmp::Ordering;
 use std::ops;
 
 use rustc::mir::{self, traversal, BasicBlock, Location};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc_data_structures::work_queue::WorkQueue;
 
diff --git a/src/librustc_mir/dataflow/impls/borrows.rs b/src/librustc_mir/dataflow/impls/borrows.rs
index a86fcb30f4d..44f6c263fed 100644
--- a/src/librustc_mir/dataflow/impls/borrows.rs
+++ b/src/librustc_mir/dataflow/impls/borrows.rs
@@ -5,7 +5,7 @@ use rustc::mir::{self, Location, Place, PlaceBase, Body};
 use rustc::ty::{self, TyCtxt};
 use rustc::ty::RegionVid;
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 
diff --git a/src/librustc_mir/dataflow/impls/mod.rs b/src/librustc_mir/dataflow/impls/mod.rs
index d669c786c09..ee33e9d47ab 100644
--- a/src/librustc_mir/dataflow/impls/mod.rs
+++ b/src/librustc_mir/dataflow/impls/mod.rs
@@ -4,7 +4,7 @@
 
 use rustc::ty::TyCtxt;
 use rustc::mir::{self, Body, Location};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::Idx;
 
 use super::MoveDataParamEnv;
diff --git a/src/librustc_mir/dataflow/mod.rs b/src/librustc_mir/dataflow/mod.rs
index 47eb47cf664..09362e31795 100644
--- a/src/librustc_mir/dataflow/mod.rs
+++ b/src/librustc_mir/dataflow/mod.rs
@@ -1,7 +1,7 @@
 use syntax::ast::{self, MetaItem};
 use syntax::symbol::{Symbol, sym};
 
-use rustc_data_structures::bit_set::{BitSet, HybridBitSet};
+use rustc_index::bit_set::{BitSet, HybridBitSet};
 use rustc_data_structures::indexed_vec::Idx;
 use rustc_data_structures::work_queue::WorkQueue;
 
diff --git a/src/librustc_mir/lints.rs b/src/librustc_mir/lints.rs
index 4f978051eac..da3fead1f9d 100644
--- a/src/librustc_mir/lints.rs
+++ b/src/librustc_mir/lints.rs
@@ -1,4 +1,4 @@
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc::hir::def_id::DefId;
 use rustc::hir::intravisit::FnKind;
 use rustc::hir::map::blocks::FnLikeNode;
diff --git a/src/librustc_mir/monomorphize/collector.rs b/src/librustc_mir/monomorphize/collector.rs
index cc8f4759e18..9c58e2aa16c 100644
--- a/src/librustc_mir/monomorphize/collector.rs
+++ b/src/librustc_mir/monomorphize/collector.rs
@@ -194,7 +194,7 @@ use crate::monomorphize;
 use rustc::util::nodemap::{FxHashSet, FxHashMap, DefIdMap};
 use rustc::util::common::time;
 
-use rustc_data_structures::bit_set::GrowableBitSet;
+use rustc_index::bit_set::GrowableBitSet;
 use rustc_data_structures::sync::{MTRef, MTLock, ParallelIterator, par_iter};
 
 use std::iter;
diff --git a/src/librustc_mir/transform/elaborate_drops.rs b/src/librustc_mir/transform/elaborate_drops.rs
index d7b6810a865..f91a08bcd9a 100644
--- a/src/librustc_mir/transform/elaborate_drops.rs
+++ b/src/librustc_mir/transform/elaborate_drops.rs
@@ -14,7 +14,7 @@ use rustc::ty::layout::VariantIdx;
 use rustc::hir;
 use rustc::mir::*;
 use rustc::util::nodemap::FxHashMap;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use std::fmt;
 use syntax_pos::Span;
 
diff --git a/src/librustc_mir/transform/generator.rs b/src/librustc_mir/transform/generator.rs
index 2b66e602370..649665b4aba 100644
--- a/src/librustc_mir/transform/generator.rs
+++ b/src/librustc_mir/transform/generator.rs
@@ -59,7 +59,7 @@ use rustc::ty::layout::VariantIdx;
 use rustc::ty::subst::SubstsRef;
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
-use rustc_data_structures::bit_set::{BitSet, BitMatrix};
+use rustc_index::bit_set::{BitSet, BitMatrix};
 use std::borrow::Cow;
 use std::iter;
 use std::mem;
diff --git a/src/librustc_mir/transform/inline.rs b/src/librustc_mir/transform/inline.rs
index 7f56c6f7986..f4c522245f7 100644
--- a/src/librustc_mir/transform/inline.rs
+++ b/src/librustc_mir/transform/inline.rs
@@ -3,7 +3,7 @@
 use rustc::hir::CodegenFnAttrFlags;
 use rustc::hir::def_id::DefId;
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 
 use rustc::mir::*;
diff --git a/src/librustc_mir/transform/qualify_consts.rs b/src/librustc_mir/transform/qualify_consts.rs
index 387540655f0..ee7b0cada12 100644
--- a/src/librustc_mir/transform/qualify_consts.rs
+++ b/src/librustc_mir/transform/qualify_consts.rs
@@ -4,7 +4,7 @@
 //! The Qualif flags below can be used to also provide better
 //! diagnostics as to why a constant rvalue wasn't promoted.
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_target::spec::abi::Abi;
diff --git a/src/librustc_mir/transform/remove_noop_landing_pads.rs b/src/librustc_mir/transform/remove_noop_landing_pads.rs
index 70b11944e2f..e1994c5f639 100644
--- a/src/librustc_mir/transform/remove_noop_landing_pads.rs
+++ b/src/librustc_mir/transform/remove_noop_landing_pads.rs
@@ -1,6 +1,6 @@
 use rustc::ty::TyCtxt;
 use rustc::mir::*;
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use crate::transform::{MirPass, MirSource};
 use crate::util::patch::MirPatch;
 
diff --git a/src/librustc_mir/transform/rustc_peek.rs b/src/librustc_mir/transform/rustc_peek.rs
index 539645d0227..f509d2d7104 100644
--- a/src/librustc_mir/transform/rustc_peek.rs
+++ b/src/librustc_mir/transform/rustc_peek.rs
@@ -6,7 +6,7 @@ use syntax_pos::Span;
 use rustc::ty::{self, TyCtxt};
 use rustc::hir::def_id::DefId;
 use rustc::mir::{self, Body, Location};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use crate::transform::{MirPass, MirSource};
 
 use crate::dataflow::{do_dataflow, DebugFormatted};
diff --git a/src/librustc_mir/transform/simplify.rs b/src/librustc_mir/transform/simplify.rs
index d4599ee08aa..c6df9d49ec0 100644
--- a/src/librustc_mir/transform/simplify.rs
+++ b/src/librustc_mir/transform/simplify.rs
@@ -27,7 +27,7 @@
 //! naively generate still contains the `_a = ()` write in the unreachable block "after" the
 //! return.
 
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc::ty::TyCtxt;
 use rustc::mir::*;
diff --git a/src/librustc_mir/util/liveness.rs b/src/librustc_mir/util/liveness.rs
index b42eebc7ee3..24ee803c9f8 100644
--- a/src/librustc_mir/util/liveness.rs
+++ b/src/librustc_mir/util/liveness.rs
@@ -30,7 +30,7 @@ use rustc::mir::visit::{
 use rustc::mir::Local;
 use rustc::mir::*;
 use rustc::ty::{self, TyCtxt};
-use rustc_data_structures::bit_set::BitSet;
+use rustc_index::bit_set::BitSet;
 use rustc_data_structures::indexed_vec::{Idx, IndexVec};
 use rustc_data_structures::work_queue::WorkQueue;
 use std::fs;
diff --git a/src/libsyntax/Cargo.toml b/src/libsyntax/Cargo.toml
index 196cf4d9dfa..d8de21cc677 100644
--- a/src/libsyntax/Cargo.toml
+++ b/src/libsyntax/Cargo.toml
@@ -18,6 +18,7 @@ lazy_static = "1.0.0"
 syntax_pos = { path = "../libsyntax_pos" }
 errors = { path = "../librustc_errors", package = "rustc_errors" }
 rustc_data_structures = { path = "../librustc_data_structures" }
+rustc_index = { path = "../librustc_index" }
 rustc_lexer = { path = "../librustc_lexer" }
 rustc_target = { path = "../librustc_target" }
 smallvec = { version = "0.6.7", features = ["union", "may_dangle"] }
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 2c10220c766..d2c76b669dd 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -26,7 +26,7 @@ extern crate proc_macro;
 
 pub use errors;
 use rustc_data_structures::sync::Lock;
-use rustc_data_structures::bit_set::GrowableBitSet;
+use rustc_index::bit_set::GrowableBitSet;
 pub use rustc_data_structures::thin_vec::ThinVec;
 use ast::AttrId;
 use syntax_pos::edition::Edition;