Index: clang-modernize/Core/Transform.cpp
===================================================================
--- clang-modernize/Core/Transform.cpp
+++ clang-modernize/Core/Transform.cpp
@@ -98,7 +98,13 @@
   assert(Overrides != 0 && "Subclass transform didn't provide InputState");
 
   Overrides->applyOverrides(CI.getSourceManager());
-  CurrentSource = Filename;
+
+  llvm::SmallString<256> FilePath(Filename);
+  llvm::error_code EC = llvm::sys::fs::make_absolute(FilePath);
+  assert(!EC && "File path can't be made absolute");
+  (void) EC;
+
+  CurrentSource = FilePath.c_str();
 
   if (Options().EnableTiming) {
     Timings.push_back(std::make_pair(Filename.str(), llvm::TimeRecord()));
Index: test/clang-modernize/Compilations/Inputs/compile_commands_rel.json
===================================================================
--- /dev/null
+++ test/clang-modernize/Compilations/Inputs/compile_commands_rel.json
@@ -0,0 +1,17 @@
+[
+{
+  "directory": "$(path)/a1/",
+  "command": "clang++ -o compilations.o -c compilations.cpp -std=c++11",
+  "file": "compilations.cpp"
+},
+{
+  "directory": "$(path)/a2/",
+  "command": "clang++ -o compilations.o -c compilations.cpp -std=c++11",
+  "file": "compilations.cpp"
+},
+{
+  "directory": "$(path)/a3/",
+  "command": "clang++ -o compilations.o -c compilations.cpp -std=c++11",
+  "file": "compilations.cpp"
+}
+]
Index: test/clang-modernize/Compilations/compilation_rel.cpp
===================================================================
--- /dev/null
+++ test/clang-modernize/Compilations/compilation_rel.cpp
@@ -0,0 +1,25 @@
+// The following block tests:
+//   - Relative paths are use in the compilation database.
+//   - A compilation database is detected from build path specified by -p and
+//     -include was provided.
+
+// Create directory structure
+// a1, a2  and a3 are specified paths for files in the compilation database.
+// RUN: rm -rf %T/CompilationRel
+// RUN: mkdir -p %T/CompilationRel
+// RUN: mkdir -p %T/CompilationRel/a1
+// RUN: mkdir -p %T/CompilationRel/a2
+// RUN: mkdir -p %T/CompilationRel/a3
+
+// This test uses a compilation database
+// RUN: sed -e 's#$(path)#%/T/CompilationRel#g' %S/Inputs/compile_commands_rel.json > %T/CompilationRel/compile_commands.json
+
+// Check that files are tranformed when -p and -include are specified.
+// RUN: cp %S/Inputs/compilations.cpp %T/CompilationRel/a1
+// RUN: cp %S/Inputs/compilations.cpp %T/CompilationRel/a2
+// RUN: cp %S/Inputs/compilations.cpp %T/CompilationRel/a3
+
+// RUN: clang-modernize -use-nullptr -p=%T/CompilationRel -include=%T/CompilationRel/a1,%T/CompilationRel/a3
+// RUN: diff -b %S/Inputs/compilations_expected.cpp %T/CompilationRel/a1/compilations.cpp
+// RUN: not diff -b %S/Inputs/compilations_expected.cpp %T/CompilationRel/a2/compilations.cpp
+// RUN: diff -b %S/Inputs/compilations_expected.cpp %T/CompilationRel/a3/compilations.cpp
Index: test/clang-modernize/Compilations/no_compilation_rel.cpp
===================================================================
--- /dev/null
+++ test/clang-modernize/Compilations/no_compilation_rel.cpp
@@ -0,0 +1,19 @@
+// The following block tests that files are transformed when specified using
+// relative paths.
+
+// Create directory structure
+// a1, a2  and a3 are specified paths for files in the compilation database.
+// RUN: rm -rf %T/NoCompilationRel
+// RUN: mkdir -p %T/NoCompilationRel
+// RUN: mkdir -p %T/NoCompilationRel/a1
+// RUN: mkdir -p %T/NoCompilationRel/a2
+// RUN: mkdir -p %T/NoCompilationRel/a3
+
+// RUN: cp %S/Inputs/compilations.cpp %T/NoCompilationRel/a1
+// RUN: cp %S/Inputs/compilations.cpp %T/NoCompilationRel/a2
+// RUN: cp %S/Inputs/compilations.cpp %T/NoCompilationRel/a3
+// RUN: cd %T
+// RUN: clang-modernize -use-nullptr ./NoCompilationRel/a1/compilations.cpp ./NoCompilationRel/a3/compilations.cpp
+// RUN: diff -b %S/Inputs/compilations_expected.cpp %T/NoCompilationRel/a1/compilations.cpp
+// RUN: not diff -b %S/Inputs/compilations_expected.cpp %T/NoCompilationRel/a2/compilations.cpp
+// RUN: diff -b %S/Inputs/compilations_expected.cpp %T/NoCompilationRel/a3/compilations.cpp