diff --git a/clang/test/Driver/program-path-priority.c b/clang/test/Driver/program-path-priority.c
--- a/clang/test/Driver/program-path-priority.c
+++ b/clang/test/Driver/program-path-priority.c
@@ -13,6 +13,11 @@
 /// so only name priority is accounted for, unless we fail to find
 /// anything at all in the prefix.
 
+/// Note: All matches are expected to be at the end of file paths.
+/// So we match " on the end to account for build systems that
+/// put the name of the compiler in the build path.
+/// E.g. /build/gcc_X.Y.Z/0/...
+
 /// Symlink clang to a new dir which will be its
 /// "program path" for these tests
 // RUN: rm -rf %t && mkdir -p %t
@@ -21,14 +26,18 @@
 /// No gccs at all, nothing is found
 // RUN: env "PATH=" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=NO_NOTREAL_GCC %s
-// NO_NOTREAL_GCC-NOT: notreal-none-elf-gcc
-// NO_NOTREAL_GCC-NOT: /gcc
+// NO_NOTREAL_GCC-NOT: notreal-none-elf-gcc"
+/// Some systems will have "gcc-x.y.z" so for this first check
+/// make sure we don't find "gcc" or "gcc-x.y.z". If we do find either
+/// then there is no point continuing as this copy of clang is not
+/// isolated as we expected.
+// NO_NOTREAL_GCC-NOT: {{/gcc[^/]*"}}
 
 /// <triple>-gcc in program path is found
 // RUN: touch %t/notreal-none-elf-gcc && chmod +x %t/notreal-none-elf-gcc
 // RUN: env "PATH=" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=PROG_PATH_NOTREAL_GCC %s
-// PROG_PATH_NOTREAL_GCC: notreal-none-elf-gcc
+// PROG_PATH_NOTREAL_GCC: notreal-none-elf-gcc"
 
 /// <triple>-gcc on the PATH is found
 // RUN: mkdir -p %t/env
@@ -36,74 +45,89 @@
 // RUN: touch %t/env/notreal-none-elf-gcc && chmod +x %t/env/notreal-none-elf-gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=ENV_PATH_NOTREAL_GCC %s
-// ENV_PATH_NOTREAL_GCC: env/notreal-none-elf-gcc
+// ENV_PATH_NOTREAL_GCC: env/notreal-none-elf-gcc"
 
 /// <triple>-gcc in program path is preferred to one on the PATH
 // RUN: touch %t/notreal-none-elf-gcc && chmod +x %t/notreal-none-elf-gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=BOTH_NOTREAL_GCC %s
-// BOTH_NOTREAL_GCC: notreal-none-elf-gcc
-// BOTH_NOTREAL_GCC-NOT: env/notreal-none-elf-gcc
+// BOTH_NOTREAL_GCC: notreal-none-elf-gcc"
+// BOTH_NOTREAL_GCC-NOT: env/notreal-none-elf-gcc"
 
 /// On program path, <triple>-gcc is preferred to plain gcc
 // RUN: touch %t/gcc && chmod +x %t/gcc
 // RUN: env "PATH=" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=NOTREAL_GCC_PREFERRED %s
-// NOTREAL_GCC_PREFERRED: notreal-none-elf-gcc
-// NOTREAL_GCC_PREFERRED-NOT: /gcc
+// NOTREAL_GCC_PREFERRED: notreal-none-elf-gcc"
+// NOTREAL_GCC_PREFERRED-NOT: /gcc"
 
 /// <triple>-gcc on the PATH is preferred to gcc in program path
 // RUN: rm %t/notreal-none-elf-gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=NOTREAL_PATH_OVER_GCC_PROG %s
-// NOTREAL_PATH_OVER_GCC_PROG: env/notreal-none-elf-gcc
-// NOTREAL_PATH_OVER_GCC_PROG-NOT: /gcc
+// NOTREAL_PATH_OVER_GCC_PROG: env/notreal-none-elf-gcc"
+// NOTREAL_PATH_OVER_GCC_PROG-NOT: /gcc"
 
 /// <triple>-gcc on the PATH is preferred to gcc on the PATH
 // RUN: rm %t/gcc
 // RUN: touch %t/env/gcc && chmod +x %t/env/gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=NOTREAL_PATH_OVER_GCC_PATH %s
-// NOTREAL_PATH_OVER_GCC_PATH: env/notreal-none-elf-gcc
-// NOTREAL_PATH_OVER_GCC_PATH-NOT: /gcc
+// NOTREAL_PATH_OVER_GCC_PATH: env/notreal-none-elf-gcc"
+// NOTREAL_PATH_OVER_GCC_PATH-NOT: /gcc"
+
+/// We cannot trust clang --version, or cmake's LLVM_DEFAULT_TARGET_TRIPLE
+/// to give us the one and only default triple.
+/// Can't trust cmake because on Darwin, triples have a verison appended to them.
+/// (and clang uses the versioned string to search)
+/// Can't trust --version because it will pad 3 item triples to 4 e.g.
+/// powerpc64le-linux-gnu -> powerpc64le-unknown-linux-gnu
+/// (and clang uses the former to search)
+/// So we write to both names which is a bit odd but still proves that the
+/// lookup is working.
 
 /// <default-triple>-gcc has lowest priority so <triple>-gcc
 /// on PATH beats default triple in program path
-/// Darwin triples have a version appended to them, even if set via
-/// LLVM_DEFAULT_TARGET_TRIPLE. So the only way to know for sure is to ask clang.
 // RUN: DEFAULT_TRIPLE=`%t/clang --version | grep "Target:" | cut -d ' ' -f2`
 // RUN: touch %t/$DEFAULT_TRIPLE-gcc && chmod +x %t/$DEFAULT_TRIPLE-gcc
+// RUN: touch %t/%target_triple-gcc && chmod +x %t/%target_triple-gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=DEFAULT_TRIPLE_GCC %s
-// DEFAULT_TRIPLE_GCC: env/notreal-none-elf-gcc
+// DEFAULT_TRIPLE_GCC: env/notreal-none-elf-gcc"
 
 /// plain gcc on PATH beats default triple in program path
 // RUN: rm %t/env/notreal-none-elf-gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=DEFAULT_TRIPLE_NO_NOTREAL %s
-// DEFAULT_TRIPLE_NO_NOTREAL: env/gcc
-// DEFAULT_TRIPLE_NO_NOTREAL-NOT: -gcc
+// DEFAULT_TRIPLE_NO_NOTREAL: env/gcc"
+// DEFAULT_TRIPLE_NO_NOTREAL-NOT: -gcc"
 
 /// default triple only chosen when no others are present
 // RUN: rm %t/env/gcc
 // RUN: env "PATH=%t/env/" %t/clang -### -target notreal-none-elf %s 2>&1 | \
 // RUN:   FileCheck --check-prefix=DEFAULT_TRIPLE_NO_OTHERS %s
-// DEFAULT_TRIPLE_NO_OTHERS: -gcc
-// DEFAULT_TRIPLE_NO_OTHERS-NOT: notreal-none-elf-gcc
-// DEFAULT_TRIPLE_NO_OTHERS-NOT: /gcc
+// DEFAULT_TRIPLE_NO_OTHERS: -gcc"
+// DEFAULT_TRIPLE_NO_OTHERS-NOT: notreal-none-elf-gcc"
+// DEFAULT_TRIPLE_NO_OTHERS-NOT: /gcc"
 
 /// -B paths are searched separately so default triple will win
 /// if put in one of those even if other paths have higher priority names
 // RUN: mkdir -p %t/prefix
-// RUN: mv %t/$DEFAULT_TRIPLE-gcc %t/prefix
+/// One of these will fail when $DEFAULT_TRIPLE == %target_triple
+// RUN: test -f %t/$DEFAULT_TRIPLE-gcc && \
+// RUN:   mv %t/$DEFAULT_TRIPLE-gcc %t/prefix || true
+// RUN: test -f %t/%target_triple-gcc && \
+// RUN:   mv %t/%target_triple-gcc %t/prefix || true
 // RUN: touch %t/notreal-none-elf-gcc && chmod +x %t/notreal-none-elf-gcc
 // RUN: env "PATH=" %t/clang -### -target notreal-none-elf %s -B %t/prefix 2>&1 | \
 // RUN:   FileCheck --check-prefix=DEFAULT_TRIPLE_IN_PREFIX %s
-// DEFAULT_TRIPLE_IN_PREFIX: prefix/{{.*}}-gcc
-// DEFAULT_TRIPLE_IN_PREFIX-NOT: notreal-none-elf-gcc
+// DEFAULT_TRIPLE_IN_PREFIX: prefix/{{.*}}-gcc"
+// DEFAULT_TRIPLE_IN_PREFIX-NOT: notreal-none-elf-gcc"
 
 /// Only if there is nothing in the prefix will we search other paths
-// RUN: rm %t/prefix/$DEFAULT_TRIPLE-gcc
+/// -f in case $DEFAULT_TRIPLE == %target_triple
+// RUN: rm -f %t/prefix/$DEFAULT_TRIPLE-gcc
+// RUN: rm -f %t/prefix/%target_triple-gcc
 // RUN: env "PATH=" %t/clang -### -target notreal-none-elf %s -B %t/prefix 2>&1 | \
 // RUN:   FileCheck --check-prefix=EMPTY_PREFIX_DIR %s
-// EMPTY_PREFIX_DIR: notreal-none-elf-gcc
+// EMPTY_PREFIX_DIR: notreal-none-elf-gcc"
diff --git a/clang/test/lit.cfg.py b/clang/test/lit.cfg.py
--- a/clang/test/lit.cfg.py
+++ b/clang/test/lit.cfg.py
@@ -46,6 +46,8 @@
 config.substitutions.append(
     ('%src_include_dir', config.clang_src_dir + '/include'))
 
+config.substitutions.append(
+    ('%target_triple', config.target_triple))
 
 # Propagate path to symbolizer for ASan/MSan.
 llvm_config.with_system_environment(