Index: include/llvm/IR/TypeFinder.h
===================================================================
--- include/llvm/IR/TypeFinder.h
+++ include/llvm/IR/TypeFinder.h
@@ -59,6 +59,8 @@
 
   StructType *&operator[](unsigned Idx) { return StructTypes[Idx]; }
 
+  DenseSet<const MDNode *> &getVisitedMetadata() { return VisitedMetadata; }
+
 private:
   /// incorporateType - This method adds the type to the list of used
   /// structures if it's not in there already.
Index: lib/Linker/IRMover.cpp
===================================================================
--- lib/Linker/IRMover.cpp
+++ lib/Linker/IRMover.cpp
@@ -1342,6 +1342,12 @@
     else
       IdentifiedStructTypes.addNonOpaque(Ty);
   }
+  // Self-map metadatas in the destination module. This is needed when
+  // DebugTypeODRUniquing is enabled on the LLVMContext, since metadata in the
+  // destination module may be reached from the source module.
+  for (auto *MD : StructTypes.getVisitedMetadata()) {
+    SharedMDs[MD].reset(const_cast<MDNode *>(MD));
+  }
 }
 
 Error IRMover::move(
Index: test/ThinLTO/X86/Inputs/crash_debuginfo.ll
===================================================================
--- /dev/null
+++ test/ThinLTO/X86/Inputs/crash_debuginfo.ll
@@ -0,0 +1,33 @@
+; ModuleID = 'test/ThinLTO/X86/Inputs/crash_debuginfo.ll'
+source_filename = "src.bc"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.7.0"
+
+%another_type = type { i32 }
+
+define void @bar(i32 %arg) {
+  %tmp = add i32 %arg, 0, !dbg !7
+  unreachable
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "Apple LLVM version 8.0.0 (clang-800.0.25.1)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2, globals: !3, imports: !2)
+!1 = !DIFile(filename: "2.cpp", directory: "some_dir")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DIGlobalVariable(name: "a_global", linkageName: "a_global", scope: null, line: 52, type: !5, isLocal: true, isDefinition: true, variable: %another_type** undef)
+!5 = !DISubroutineType(types: !2)
+!6 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DILocation(line: 728, column: 71, scope: !8, inlinedAt: !14)
+!8 = distinct !DISubprogram(name: "baz", linkageName: "baz", scope: !9, file: !1, line: 726, type: !5, isLocal: false, isDefinition: true, scopeLine: 727, flags: DIFlagPrototyped, isOptimized: true, unit: !0, declaration: !10, variables: !11)
+!9 = distinct !DICompositeType(tag: DW_TAG_class_type, name: "some_other_class", scope: !1, file: !1, line: 197, size: 192, align: 64, elements: !2, templateParams: !2, identifier: "some_other_class")
+!10 = !DISubprogram(name: "baz", linkageName: "baz", scope: !9, file: !1, line: 726, type: !5, isLocal: false, isDefinition: false, scopeLine: 726, flags: DIFlagPrototyped, isOptimized: true)
+!11 = !{!12}
+!12 = !DILocalVariable(name: "caster", scope: !8, file: !1, line: 728, type: !13)
+!13 = distinct !DICompositeType(tag: DW_TAG_union_type, scope: !8, file: !1, line: 728, size: 64, align: 64, elements: !2, identifier: "someclass")
+!14 = distinct !DILocation(line: 795, column: 16, scope: !15)
+!15 = distinct !DILexicalBlock(scope: !16, file: !1, line: 794, column: 7)
+!16 = distinct !DISubprogram(name: "operator()", linkageName: "some_special_function", scope: null, file: !1, line: 783, type: !5, isLocal: true, isDefinition: true, scopeLine: 784, flags: DIFlagPrototyped, isOptimized: true, unit: !0, declaration: !17, variables: !2)
+!17 = !DISubprogram(name: "operator()", linkageName: "some_special_function", scope: null, file: !1, line: 783, type: !5, isLocal: false, isDefinition: false, scopeLine: 783, flags: DIFlagPrototyped, isOptimized: true)
Index: test/ThinLTO/X86/crash_debuginfo.ll
===================================================================
--- /dev/null
+++ test/ThinLTO/X86/crash_debuginfo.ll
@@ -0,0 +1,45 @@
+; RUN: opt -module-summary -o %t-dst.bc %s
+; RUN: opt -module-summary -o %t-src.bc %p/Inputs/crash_debuginfo.ll
+; RUN: llvm-lto -thinlto -o %t-index %t-dst.bc %t-src.bc
+; RUN: opt -function-import -inline -summary-file %t-index.thinlto.bc %t-dst.bc -o %t.out
+; RUN: llvm-nm %t.out | FileCheck %s
+
+; Verify that we import bar and inline it. It use to crash importing due to ODR type uniquing
+; CHECK: foo
+; CHECK-NOt: bar
+
+; ModuleID = 'test/ThinLTO/X86/crash_debuginfo.ll'
+source_filename = "test/ThinLTO/X86/crash_debuginfo.ll"
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.7.0"
+
+%some_type = type { i32 }
+
+define void @foo(i32 %arg) {
+  call void @bar(i32 %arg), !dbg !7
+  unreachable
+}
+
+declare void @bar(i32)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "Apple LLVM version 8.0.0 (clang-800.0.24.1)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2)
+!1 = !DIFile(filename: "1.cpp", directory: "/another_dir")
+!2 = !{!3}
+!3 = distinct !DIGlobalVariable(name: "_", linkageName: "some_global", scope: null, file: !1, line: 20, type: !4, isLocal: true, isDefinition: true, variable: %some_type* undef)
+!4 = distinct !DICompositeType(tag: DW_TAG_class_type, name: "slice_nil", file: !1, line: 13, size: 64, align: 64, elements: !5, identifier: "_ZTSN5boost6python3api9slice_nilE")
+!5 = !{}
+!6 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DILocation(line: 728, column: 71, scope: !8, inlinedAt: !15)
+!8 = distinct !DISubprogram(name: "baz", linkageName: "baz", scope: !9, file: !1, line: 726, type: !10, isLocal: false, isDefinition: true, scopeLine: 727, flags: DIFlagPrototyped, isOptimized: true, unit: !0, declaration: !11, variables: !12)
+!9 = distinct !DICompositeType(tag: DW_TAG_class_type, name: "some_other_class", file: !1, line: 197, size: 192, align: 64, elements: !5, templateParams: !5, identifier: "some_other_class")
+!10 = !DISubroutineType(types: !5)
+!11 = !DISubprogram(name: "baz", linkageName: "baz", scope: !9, file: !1, line: 726, type: !10, isLocal: false, isDefinition: false, scopeLine: 726, flags: DIFlagPrototyped, isOptimized: true)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "caster", scope: !8, file: !1, line: 728, type: !14)
+!14 = distinct !DICompositeType(tag: DW_TAG_union_type, scope: !8, file: !1, line: 728, size: 64, align: 64, elements: !5, identifier: "someclass")
+!15 = distinct !DILocation(line: 87, column: 9, scope: !16)
+!16 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: !9, line: 73, type: !10, isLocal: false, isDefinition: true, scopeLine: 74, flags: DIFlagPrototyped, isOptimized: true, unit: !0, declaration: !17, variables: !5)
+!17 = !DISubprogram(name: "foo", linkageName: "foo", scope: !9, file: !1, line: 83, type: !10, isLocal: false, isDefinition: false, scopeLine: 83, flags: DIFlagPrototyped, isOptimized: true)