Index: clang/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGDebugInfo.cpp
+++ clang/lib/CodeGen/CGDebugInfo.cpp
@@ -2492,12 +2492,15 @@
             ? (uint64_t)Mod.getSignature()[1] << 32 | Mod.getSignature()[0]
             : ~1ULL;
     llvm::DIBuilder DIB(CGM.getModule());
-    DIB.createCompileUnit(TheCU->getSourceLanguage(),
-                          // TODO: Support "Source" from external AST providers?
-                          DIB.createFile(Mod.getModuleName(), Mod.getPath()),
-                          TheCU->getProducer(), true, StringRef(), 0,
-                          Mod.getASTFile(), llvm::DICompileUnit::FullDebug,
-                          Signature);
+    std::string PCM = remapDIPath(Mod.getASTFile());
+    StringRef RelativePCM(PCM);
+    RelativePCM.consume_front(TheCU->getDirectory());
+    DIB.createCompileUnit(
+        TheCU->getSourceLanguage(),
+        // TODO: Support "Source" from external AST providers?
+        DIB.createFile(Mod.getModuleName(), TheCU->getDirectory()),
+        TheCU->getProducer(), false, StringRef(), 0, RelativePCM,
+        llvm::DICompileUnit::FullDebug, Signature);
     DIB.finalize();
   }
 
Index: clang/test/Modules/debug-info-moduleimport.m
===================================================================
--- clang/test/Modules/debug-info-moduleimport.m
+++ clang/test/Modules/debug-info-moduleimport.m
@@ -1,11 +1,19 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -DGREETING="Hello World" -UNDEBUG -fimplicit-module-maps -fmodules-cache-path=%t %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - | FileCheck %s --check-prefix=NOIMPORT
+// RUN: %clang_cc1 -debug-info-kind=limited -fmodules \
+// RUN:     -DGREETING="Hello World" -UNDEBUG \
+// RUN:     -fimplicit-module-maps -fmodules-cache-path=%t %s \
+// RUN:     -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
+// RUN:     | FileCheck %s --check-prefix=NOIMPORT
 
 // NOIMPORT-NOT: !DIImportedEntity
 // NOIMPORT-NOT: !DIModule
 
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -DGREETING="Hello World" -UNDEBUG -fimplicit-module-maps -fmodules-cache-path=%t %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -debugger-tuning=lldb -o - | FileCheck %s
+// RUN: %clang_cc1 -debug-info-kind=limited -fmodules \
+// RUN:    -DGREETING="Hello World" -UNDEBUG \
+// RUN:    -fimplicit-module-maps -fmodules-cache-path=%t %s \
+// RUN:    -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm \
+// RUN:    -debugger-tuning=lldb -o - | FileCheck %s
 
 // CHECK: ![[CU:.*]] = distinct !DICompileUnit
 // CHECK-SAME:  sysroot: "/tmp/..")
@@ -18,15 +26,18 @@
 // CHECK-SAME:  includePath: "{{.*}}test{{.*}}Modules{{.*}}Inputs"
 // CHECK: ![[F]] = !DIFile(filename: {{.*}}debug-info-moduleimport.m
 
-// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
-// RUN:   %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
-// RUN:     | FileCheck %s --check-prefix=NO-SKEL-CHECK
+// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps \
+// RUN:   -fmodules-cache-path=%t %s -I %S/Inputs -isysroot /tmp/.. -I %t \
+// RUN:   -emit-llvm -o - | FileCheck %s --check-prefix=NO-SKEL-CHECK
 // NO-SKEL-CHECK: distinct !DICompileUnit
 // NO-SKEL-CHECK-NOT: distinct !DICompileUnit
 
-// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps -fmodules-cache-path=%t \
+// RUN: %clang_cc1 -debug-info-kind=limited -fmodules -fimplicit-module-maps \
+// RUN:   -fmodules-cache-path=%t -fdebug-prefix-map=%t=/MODULE-CACHE \
 // RUN:   -fmodule-format=obj -dwarf-ext-refs \
 // RUN:   %s -I %S/Inputs -isysroot /tmp/.. -I %t -emit-llvm -o - \
 // RUN:     | FileCheck %s --check-prefix=SKEL-CHECK
-// SKEL-CHECK: distinct !DICompileUnit
-// SKEL-CHECK: distinct !DICompileUnit{{.*}}dwoId
+// SKEL-CHECK: distinct !DICompileUnit({{.*}}file: ![[CUFILE:[0-9]+]]
+// SKEL-CHECK: ![[CUFILE]] = !DIFile({{.*}}directory: "[[COMP_DIR:.*]]"
+// SKEL-CHECK: distinct !DICompileUnit({{.*}}file: ![[DWOFILE:[0-9]+]]{{.*}}splitDebugFilename: "/MODULE-CACHE{{.*}}dwoId
+// SKEL-CHECK: ![[DWOFILE]] = !DIFile({{.*}}directory: "[[COMP_DIR]]"