Index: COFF/Writer.cpp
===================================================================
--- COFF/Writer.cpp
+++ COFF/Writer.cpp
@@ -373,14 +373,14 @@
 // After adding thunks, we verify that all relocations are in range (with
 // no extra margin requirements). If this failed, we restart (throwing away
 // the previously created thunks) and retry with a wider margin.
-static bool createThunks(std::vector<Chunk *> &Chunks, int Margin) {
+static bool createThunks(OutputSection *OS, int Margin) {
   bool AddressesChanged = false;
   DenseMap<uint64_t, Defined *> LastThunks;
   size_t ThunksSize = 0;
   // Recheck Chunks.size() each iteration, since we can insert more
   // elements into it.
-  for (size_t I = 0; I != Chunks.size(); ++I) {
-    SectionChunk *SC = dyn_cast_or_null<SectionChunk>(Chunks[I]);
+  for (size_t I = 0; I != OS->Chunks.size(); ++I) {
+    SectionChunk *SC = dyn_cast_or_null<SectionChunk>(OS->Chunks[I]);
     if (!SC)
       continue;
     size_t ThunkInsertionSpot = I + 1;
@@ -417,7 +417,8 @@
         Chunk *ThunkChunk = Thunk->getChunk();
         ThunkChunk->setRVA(
             ThunkInsertionRVA); // Estimate of where it will be located.
-        Chunks.insert(Chunks.begin() + ThunkInsertionSpot, ThunkChunk);
+        ThunkChunk->setOutputSection(OS);
+        OS->Chunks.insert(OS->Chunks.begin() + ThunkInsertionSpot, ThunkChunk);
         ThunkInsertionSpot++;
         ThunksSize += ThunkChunk->getSize();
         ThunkInsertionRVA += ThunkChunk->getSize();
@@ -506,7 +507,7 @@
     // to avoid things going out of range due to the added thunks.
     bool AddressesChanged = false;
     for (OutputSection *Sec : OutputSections)
-      AddressesChanged |= createThunks(Sec->Chunks, Margin);
+      AddressesChanged |= createThunks(Sec, Margin);
     // If the verification above thought we needed thunks, we should have
     // added some.
     assert(AddressesChanged);
Index: test/COFF/arm-thumb-thunks-pdb.s
===================================================================
--- /dev/null
+++ test/COFF/arm-thumb-thunks-pdb.s
@@ -0,0 +1,19 @@
+// REQUIRES: arm
+// RUN: llvm-mc -filetype=obj -triple=thumbv7-windows %s -o %t.obj
+// RUN: lld-link -entry:main -subsystem:console %t.obj -out:%t.exe -debug -pdb:%t.pdb -verbose 2>&1 | FileCheck %s --check-prefix=VERBOSE
+
+// VERBOSE: Added 1 thunks with margin {{.*}} in {{.*}} passes
+
+
+    .syntax unified
+    .globl main
+    .globl func1
+    .text
+main:
+    bne func1
+    bx lr
+    .section .text$a, "xr"
+    .space 0x100000
+    .section .text$b, "xr"
+func1:
+    bx lr