diff --git a/src/Makefile.sources b/src/Makefile.sources
index 7211fb0d5..f72abcc47 100644
--- a/src/Makefile.sources
+++ b/src/Makefile.sources
@@ -118,7 +118,7 @@ HB_BASE_sources = \
 	OT/Layout/GSUB/ExtensionSubst.hh \
 	OT/Layout/GSUB/SubstLookupSubTable.hh \
 	OT/Layout/GSUB/SubstLookup.hh \
-	OT/Layout/GSUB/GSUB.hh \
+	OT/Layout/GSUB.hh \
 	OT/Layout/GPOS.hh \
 	OT/Layout/GPOS/CursivePosFormat1.hh \
 	OT/Layout/GPOS/MarkLigPos.hh \
diff --git a/src/OT/Layout/GSUB/GSUB.hh b/src/OT/Layout/GSUB.hh
similarity index 72%
rename from src/OT/Layout/GSUB/GSUB.hh
rename to src/OT/Layout/GSUB.hh
index 3f0c4b2ad..d274b26fc 100644
--- a/src/OT/Layout/GSUB/GSUB.hh
+++ b/src/OT/Layout/GSUB.hh
@@ -1,16 +1,14 @@
-#ifndef OT_LAYOUT_GSUB_GSUB_HH
-#define OT_LAYOUT_GSUB_GSUB_HH
+#ifndef OT_LAYOUT_GSUB_HH
+#define OT_LAYOUT_GSUB_HH
 
-// TODO(garretrieger): move to new layout.
-#include "../../../hb-ot-layout-gsubgpos.hh"
-#include "Common.hh"
-#include "SubstLookup.hh"
+#include "../../hb-ot-layout-gsubgpos.hh"
+#include "GSUB/Common.hh"
+#include "GSUB/SubstLookup.hh"
 
-using OT::Layout::GSUB::SubstLookup;
+using OT::Layout::GSUB_impl::SubstLookup;
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
 
 /*
  * GSUB -- Glyph Substitution
@@ -47,14 +45,13 @@ struct GSUB : GSUBGPOS
 };
 
 
-}
 }
 
-struct GSUB_accelerator_t : Layout::GSUB::GSUB::accelerator_t {
-  GSUB_accelerator_t (hb_face_t *face) : Layout::GSUB::GSUB::accelerator_t (face) {}
+struct GSUB_accelerator_t : Layout::GSUB::accelerator_t {
+  GSUB_accelerator_t (hb_face_t *face) : Layout::GSUB::accelerator_t (face) {}
 };
 
 
 }
 
-#endif  /* OT_LAYOUT_GSUB_GSUB_HH */
+#endif  /* OT_LAYOUT_GSUB_HH */
diff --git a/src/OT/Layout/GSUB/AlternateSet.hh b/src/OT/Layout/GSUB/AlternateSet.hh
index 484f34746..9904cbcc1 100644
--- a/src/OT/Layout/GSUB/AlternateSet.hh
+++ b/src/OT/Layout/GSUB/AlternateSet.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct AlternateSet
 {
diff --git a/src/OT/Layout/GSUB/AlternateSubst.hh b/src/OT/Layout/GSUB/AlternateSubst.hh
index e5d999261..c87e1412f 100644
--- a/src/OT/Layout/GSUB/AlternateSubst.hh
+++ b/src/OT/Layout/GSUB/AlternateSubst.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct AlternateSubst
 {
diff --git a/src/OT/Layout/GSUB/AlternateSubstFormat1.hh b/src/OT/Layout/GSUB/AlternateSubstFormat1.hh
index af1cd7bed..125d8f927 100644
--- a/src/OT/Layout/GSUB/AlternateSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/AlternateSubstFormat1.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct AlternateSubstFormat1
 {
diff --git a/src/OT/Layout/GSUB/ChainContextSubst.hh b/src/OT/Layout/GSUB/ChainContextSubst.hh
index bbb88b222..08fd779f7 100644
--- a/src/OT/Layout/GSUB/ChainContextSubst.hh
+++ b/src/OT/Layout/GSUB/ChainContextSubst.hh
@@ -7,7 +7,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct ChainContextSubst : ChainContext {};
 
diff --git a/src/OT/Layout/GSUB/Common.hh b/src/OT/Layout/GSUB/Common.hh
index f4c78a9f0..968bba048 100644
--- a/src/OT/Layout/GSUB/Common.hh
+++ b/src/OT/Layout/GSUB/Common.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 typedef hb_pair_t<hb_codepoint_t, hb_codepoint_t> hb_codepoint_pair_t;
 
diff --git a/src/OT/Layout/GSUB/ContextSubst.hh b/src/OT/Layout/GSUB/ContextSubst.hh
index 2af54e8ff..9f8cb46b5 100644
--- a/src/OT/Layout/GSUB/ContextSubst.hh
+++ b/src/OT/Layout/GSUB/ContextSubst.hh
@@ -7,7 +7,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct ContextSubst : Context {};
 
diff --git a/src/OT/Layout/GSUB/ExtensionSubst.hh b/src/OT/Layout/GSUB/ExtensionSubst.hh
index 40a3ff439..831a7dfa2 100644
--- a/src/OT/Layout/GSUB/ExtensionSubst.hh
+++ b/src/OT/Layout/GSUB/ExtensionSubst.hh
@@ -7,7 +7,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct ExtensionSubst : Extension<ExtensionSubst>
 {
diff --git a/src/OT/Layout/GSUB/Ligature.hh b/src/OT/Layout/GSUB/Ligature.hh
index 0448d925d..9055ca011 100644
--- a/src/OT/Layout/GSUB/Ligature.hh
+++ b/src/OT/Layout/GSUB/Ligature.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct Ligature
 {
diff --git a/src/OT/Layout/GSUB/LigatureSet.hh b/src/OT/Layout/GSUB/LigatureSet.hh
index 185b324b3..370072f5e 100644
--- a/src/OT/Layout/GSUB/LigatureSet.hh
+++ b/src/OT/Layout/GSUB/LigatureSet.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct LigatureSet
 {
diff --git a/src/OT/Layout/GSUB/LigatureSubst.hh b/src/OT/Layout/GSUB/LigatureSubst.hh
index a029bf5e9..43a13e014 100644
--- a/src/OT/Layout/GSUB/LigatureSubst.hh
+++ b/src/OT/Layout/GSUB/LigatureSubst.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct LigatureSubst
 {
diff --git a/src/OT/Layout/GSUB/LigatureSubstFormat1.hh b/src/OT/Layout/GSUB/LigatureSubstFormat1.hh
index 19dfe9846..bfdbf38c5 100644
--- a/src/OT/Layout/GSUB/LigatureSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/LigatureSubstFormat1.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct LigatureSubstFormat1
 {
diff --git a/src/OT/Layout/GSUB/MultipleSubst.hh b/src/OT/Layout/GSUB/MultipleSubst.hh
index b28917550..b7a966603 100644
--- a/src/OT/Layout/GSUB/MultipleSubst.hh
+++ b/src/OT/Layout/GSUB/MultipleSubst.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct MultipleSubst
 {
diff --git a/src/OT/Layout/GSUB/MultipleSubstFormat1.hh b/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
index 54c6dc847..989901833 100644
--- a/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/MultipleSubstFormat1.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct MultipleSubstFormat1
 {
diff --git a/src/OT/Layout/GSUB/ReverseChainSingleSubst.hh b/src/OT/Layout/GSUB/ReverseChainSingleSubst.hh
index 435d80fd3..48e208efb 100644
--- a/src/OT/Layout/GSUB/ReverseChainSingleSubst.hh
+++ b/src/OT/Layout/GSUB/ReverseChainSingleSubst.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct ReverseChainSingleSubst
 {
diff --git a/src/OT/Layout/GSUB/ReverseChainSingleSubstFormat1.hh b/src/OT/Layout/GSUB/ReverseChainSingleSubstFormat1.hh
index 7a79a9df2..dfc407f7f 100644
--- a/src/OT/Layout/GSUB/ReverseChainSingleSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/ReverseChainSingleSubstFormat1.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct ReverseChainSingleSubstFormat1
 {
diff --git a/src/OT/Layout/GSUB/Sequence.hh b/src/OT/Layout/GSUB/Sequence.hh
index ebd451e6b..ffdc15b6e 100644
--- a/src/OT/Layout/GSUB/Sequence.hh
+++ b/src/OT/Layout/GSUB/Sequence.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct Sequence
 {
diff --git a/src/OT/Layout/GSUB/SingleSubst.hh b/src/OT/Layout/GSUB/SingleSubst.hh
index 786428fe4..38ffc6ac5 100644
--- a/src/OT/Layout/GSUB/SingleSubst.hh
+++ b/src/OT/Layout/GSUB/SingleSubst.hh
@@ -7,7 +7,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct SingleSubst
 {
diff --git a/src/OT/Layout/GSUB/SingleSubstFormat1.hh b/src/OT/Layout/GSUB/SingleSubstFormat1.hh
index 3c6b2954c..57d13539c 100644
--- a/src/OT/Layout/GSUB/SingleSubstFormat1.hh
+++ b/src/OT/Layout/GSUB/SingleSubstFormat1.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct SingleSubstFormat1
 {
diff --git a/src/OT/Layout/GSUB/SingleSubstFormat2.hh b/src/OT/Layout/GSUB/SingleSubstFormat2.hh
index df75bb52b..4f954ae2f 100644
--- a/src/OT/Layout/GSUB/SingleSubstFormat2.hh
+++ b/src/OT/Layout/GSUB/SingleSubstFormat2.hh
@@ -5,7 +5,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct SingleSubstFormat2
 {
diff --git a/src/OT/Layout/GSUB/SubstLookup.hh b/src/OT/Layout/GSUB/SubstLookup.hh
index 8fb3b5509..d1a8dfca1 100644
--- a/src/OT/Layout/GSUB/SubstLookup.hh
+++ b/src/OT/Layout/GSUB/SubstLookup.hh
@@ -6,7 +6,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct SubstLookup : Lookup
 {
diff --git a/src/OT/Layout/GSUB/SubstLookupSubTable.hh b/src/OT/Layout/GSUB/SubstLookupSubTable.hh
index 53e963e2a..a525fba03 100644
--- a/src/OT/Layout/GSUB/SubstLookupSubTable.hh
+++ b/src/OT/Layout/GSUB/SubstLookupSubTable.hh
@@ -13,7 +13,7 @@
 
 namespace OT {
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
 
 struct SubstLookupSubTable
 {
diff --git a/src/hb-ot-layout-gsub-table.hh b/src/hb-ot-layout-gsub-table.hh
index 462542025..d6e53d13d 100644
--- a/src/hb-ot-layout-gsub-table.hh
+++ b/src/hb-ot-layout-gsub-table.hh
@@ -29,12 +29,12 @@
 #ifndef HB_OT_LAYOUT_GSUB_TABLE_HH
 #define HB_OT_LAYOUT_GSUB_TABLE_HH
 
-#include "OT/Layout/GSUB/GSUB.hh"
+#include "OT/Layout/GSUB.hh"
 
 namespace OT {
 
-using Layout::GSUB::SubstLookup;
-using Layout::GSUB::ExtensionSubst;
+using Layout::GSUB_impl::SubstLookup;
+using Layout::GSUB_impl::ExtensionSubst;
 
 // TODO(garretrieger): Move into the new layout directory.
 /* Out-of-class implementation for methods recursing */
diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index cefdf1b96..f9c0daa48 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -54,7 +54,7 @@
 #include "hb-aat-layout-morx-table.hh"
 #include "hb-aat-layout-opbd-table.hh" // Just so we compile it; unused otherwise.
 
-using OT::Layout::GSUB::GSUB;
+using OT::Layout::GSUB;
 using OT::Layout::GPOS;
 
 /**
diff --git a/src/hb-ot-layout.hh b/src/hb-ot-layout.hh
index 6395f0667..de06610cb 100644
--- a/src/hb-ot-layout.hh
+++ b/src/hb-ot-layout.hh
@@ -110,7 +110,7 @@ namespace OT {
   struct hb_ot_apply_context_t;
   struct hb_ot_layout_lookup_accelerator_t;
 namespace Layout {
-namespace GSUB {
+namespace GSUB_impl {
   struct SubstLookup;
 }
 }
@@ -118,7 +118,7 @@ namespace GSUB {
 
 HB_INTERNAL void
 hb_ot_layout_substitute_lookup (OT::hb_ot_apply_context_t *c,
-				const OT::Layout::GSUB::SubstLookup &lookup,
+				const OT::Layout::GSUB_impl::SubstLookup &lookup,
 				const OT::hb_ot_layout_lookup_accelerator_t &accel);
 
 
diff --git a/src/hb-subset-plan.cc b/src/hb-subset-plan.cc
index c15a3664b..510176bcb 100644
--- a/src/hb-subset-plan.cc
+++ b/src/hb-subset-plan.cc
@@ -40,7 +40,7 @@
 #include "hb-ot-stat-table.hh"
 #include "hb-ot-math-table.hh"
 
-using OT::Layout::GSUB::GSUB;
+using OT::Layout::GSUB;
 using OT::Layout::GPOS;
 
 typedef hb_hashmap_t<unsigned, hb::unique_ptr<hb_set_t>> script_langsys_map;
diff --git a/src/hb-subset.cc b/src/hb-subset.cc
index 10c572c2f..8cb814dfb 100644
--- a/src/hb-subset.cc
+++ b/src/hb-subset.cc
@@ -55,7 +55,7 @@
 #include "hb-ot-math-table.hh"
 #include "hb-repacker.hh"
 
-using OT::Layout::GSUB::GSUB;
+using OT::Layout::GSUB;
 using OT::Layout::GPOS;
 
 /**
diff --git a/src/meson.build b/src/meson.build
index b4fc6d408..f9934c86b 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -122,7 +122,7 @@ hb_base_sources = files(
   'OT/Layout/GSUB/ExtensionSubst.hh',
   'OT/Layout/GSUB/SubstLookupSubTable.hh',
   'OT/Layout/GSUB/SubstLookup.hh',
-  'OT/Layout/GSUB/GSUB.hh',
+  'OT/Layout/GSUB.hh',
   'OT/Layout/GPOS.hh',
   'OT/Layout/GPOS/CursivePosFormat1.hh',
   'OT/Layout/GPOS/MarkLigPos.hh',