Index: test/BugPoint/compile-custom.ll
===================================================================
--- test/BugPoint/compile-custom.ll
+++ test/BugPoint/compile-custom.ll
@@ -1,4 +1,4 @@
-; RUN: bugpoint -load %llvmshlibdir/BugpointPasses%shlibext --compile-custom --compile-command="%python %/s.py arg1 arg2" --opt-command opt --output-prefix %t %s | FileCheck %s
+; RUN: bugpoint -load %llvmshlibdir/BugpointPasses%shlibext --compile-custom --compile-command="%/s.py arg1 arg2" --opt-command opt --output-prefix %t %s | FileCheck %s
 ; REQUIRES: loadable_module
 
 ; Test that arguments are correctly passed in --compile-command.  The output
Index: test/BugPoint/unsymbolized.ll
===================================================================
--- test/BugPoint/unsymbolized.ll
+++ test/BugPoint/unsymbolized.ll
@@ -2,7 +2,7 @@
 ; RUN: echo "import sys" > %t.py
 ; RUN: echo "print('args = ' + str(sys.argv))" >> %t.py
 ; RUN: echo "exit(1)" >> %t.py
-; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command="%python" -opt-args %t.py | FileCheck %s
+; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command=%python -opt-args %t.py | FileCheck %s
 ; RUN: not --crash opt -load %llvmshlibdir/BugpointPasses%shlibext %s -bugpoint-crashcalls -disable-symbolication 2>&1 | FileCheck --check-prefix=CRASH %s
 ; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command=%t.non.existent.opt.binary -opt-args %t.py 2>&1 | FileCheck %s --check-prefix=BAD-OPT
 
Index: test/Other/opt-bisect-legacy-pass-manager.ll
===================================================================
--- test/Other/opt-bisect-legacy-pass-manager.ll
+++ test/Other/opt-bisect-legacy-pass-manager.ll
@@ -38,7 +38,7 @@
 ; utils/bisect) to locate the optimization that inlines the call to
 ; f2() in f3().
 
-; RUN: '%python' %S/opt-bisect-helper.py --start=0 --end=256 --optcmd=opt \
+; RUN: %python %S/opt-bisect-helper.py --start=0 --end=256 --optcmd=opt \
 ; RUN:         --filecheckcmd=FileCheck --test=%s \
 ; RUN:         --prefix=CHECK-BISECT-INLINE-HELPER \
 ; RUN:         | FileCheck %s --check-prefix=CHECK-BISECT-INLINE-RESULT
Index: test/TableGen/JSON.td
===================================================================
--- test/TableGen/JSON.td
+++ test/TableGen/JSON.td
@@ -1,4 +1,4 @@
-// RUN: llvm-tblgen -dump-json %s | '%python' %S/JSON-check.py %s
+// RUN: llvm-tblgen -dump-json %s | %python %S/JSON-check.py %s
 
 // CHECK: data['!tablegen_json_version'] == 1
 
Index: test/ThinLTO/X86/cache.ll
===================================================================
--- test/ThinLTO/X86/cache.ll
+++ test/ThinLTO/X86/cache.ll
@@ -106,11 +106,11 @@
 ; RUN: rm -Rf %t.cache && mkdir %t.cache
 ; Create cache files with different sizes.
 ; Only 8B, 16B and 76B files should stay after pruning.
-; RUN: "%python" -c "with open(r'%t.cache/llvmcache-foo-1024', 'w') as file: file.truncate(1024)"
-; RUN: "%python" -c "with open(r'%t.cache/llvmcache-foo-16', 'w') as file: file.truncate(16)"
-; RUN: "%python" -c "with open(r'%t.cache/llvmcache-foo-8', 'w') as file: file.truncate(8)"
-; RUN: "%python" -c "with open(r'%t.cache/llvmcache-foo-76', 'w') as file: file.truncate(76)"
-; RUN: "%python" -c "with open(r'%t.cache/llvmcache-foo-77', 'w') as file: file.truncate(77)"
+; RUN: %python -c "with open(r'%t.cache/llvmcache-foo-1024', 'w') as file: file.truncate(1024)"
+; RUN: %python -c "with open(r'%t.cache/llvmcache-foo-16', 'w') as file: file.truncate(16)"
+; RUN: %python -c "with open(r'%t.cache/llvmcache-foo-8', 'w') as file: file.truncate(8)"
+; RUN: %python -c "with open(r'%t.cache/llvmcache-foo-76', 'w') as file: file.truncate(76)"
+; RUN: %python -c "with open(r'%t.cache/llvmcache-foo-77', 'w') as file: file.truncate(77)"
 ; RUN: llvm-lto -thinlto-action=run -exported-symbol=globalfunc %t2.bc %t.bc -thinlto-cache-dir %t.cache --thinlto-cache-max-size-bytes 100
 ; RUN: ls %t.cache/llvmcache-foo-16
 ; RUN: ls %t.cache/llvmcache-foo-8
@@ -123,11 +123,11 @@
 ; RUN: rm -Rf %t.cache && mkdir %t.cache
 ; Create cache files with different sizes.
 ; Only 8B and 16B files should stay after pruning.
-; RUN: "%python" -c "print(' ' * 1023)" > %t.cache/llvmcache-foo-1024
-; RUN: "%python" -c "print(' ' * 15)" > %t.cache/llvmcache-foo-16
-; RUN: "%python" -c "print(' ' * 7)" > %t.cache/llvmcache-foo-8
-; RUN: "%python" -c "print(' ' * 75)" > %t.cache/llvmcache-foo-76
-; RUN: "%python" -c "print(' ' * 76)" > %t.cache/llvmcache-foo-77
+; RUN: %python -c "print(' ' * 1023)" > %t.cache/llvmcache-foo-1024
+; RUN: %python -c "print(' ' * 15)" > %t.cache/llvmcache-foo-16
+; RUN: %python -c "print(' ' * 7)" > %t.cache/llvmcache-foo-8
+; RUN: %python -c "print(' ' * 75)" > %t.cache/llvmcache-foo-76
+; RUN: %python -c "print(' ' * 76)" > %t.cache/llvmcache-foo-77
 ; RUN: llvm-lto -thinlto-action=run -exported-symbol=globalfunc %t2.bc %t.bc -thinlto-cache-dir %t.cache --thinlto-cache-max-size-files 2
 ; RUN: ls %t.cache/llvmcache-foo-16
 ; RUN: ls %t.cache/llvmcache-foo-8
Index: test/tools/llvm-cov/showLineExecutionCounts.cpp
===================================================================
--- test/tools/llvm-cov/showLineExecutionCounts.cpp
+++ test/tools/llvm-cov/showLineExecutionCounts.cpp
@@ -37,7 +37,7 @@
 //
 // RUN: llvm-cov export %S/Inputs/lineExecutionCounts.covmapping -instr-profile %t.profdata -name=main 2>/dev/null > %t.export.json
 // RUN: FileCheck -input-file %t.export.json %S/Inputs/lineExecutionCounts.json
-// RUN: cat %t.export.json | "%python" -c "import json, sys; json.loads(sys.stdin.read())"
+// RUN: cat %t.export.json | %python -c "import json, sys; json.loads(sys.stdin.read())"
 //
 // RUN: llvm-cov export %S/Inputs/lineExecutionCounts.covmapping -instr-profile %t.profdata 2>/dev/null -summary-only > %t.export-summary.json
 // RUN: not grep '"name":"main"' %t.export-summary.json
Index: test/tools/llvm-objcopy/auto-remove-shndx.test
===================================================================
--- test/tools/llvm-objcopy/auto-remove-shndx.test
+++ test/tools/llvm-objcopy/auto-remove-shndx.test
@@ -1,4 +1,4 @@
-# RUN: '%python' %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
+# RUN: %python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
 # RUN: llvm-objcopy -R .text -R s0 -R s1 -R s2 -R s3 -R s4 -R s5 -R s6 %t %t2
 # RUN: llvm-readobj -sections %t2 | FileCheck --check-prefix=SECS %s
 
Index: test/tools/llvm-objcopy/many-sections.test
===================================================================
--- test/tools/llvm-objcopy/many-sections.test
+++ test/tools/llvm-objcopy/many-sections.test
@@ -1,4 +1,4 @@
-RUN: '%python' %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
+RUN: %python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
 RUN: llvm-objcopy %t %t2
 RUN: llvm-readobj -file-headers %t2 | FileCheck --check-prefix=EHDR %s
 RUN: llvm-readobj -sections %t2 | FileCheck --check-prefix=SECS %s
Index: test/tools/llvm-objcopy/remove-shndx.test
===================================================================
--- test/tools/llvm-objcopy/remove-shndx.test
+++ test/tools/llvm-objcopy/remove-shndx.test
@@ -1,6 +1,6 @@
 # This test checks to see that a .symtab_shndx section is added to any binary
 # that needs it, even if the original was removed.
-RUN: '%python' %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
+RUN: %python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t
 RUN: llvm-objcopy -R .symtab_shndx %t %t2
 RUN: llvm-readobj -sections %t2 | FileCheck %s
 
Index: test/tools/llvm-objcopy/strict-no-add.test
===================================================================
--- test/tools/llvm-objcopy/strict-no-add.test
+++ test/tools/llvm-objcopy/strict-no-add.test
@@ -1,7 +1,7 @@
 # This test makes sure that sections added at the end that don't have symbols
 # defined in them don't trigger the creation of a large index table.
 
-RUN: '%python' %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t.0
+RUN: %python %p/Inputs/ungzip.py %p/Inputs/many-sections.o.gz > %t.0
 RUN: cat %p/Inputs/alloc-symtab.o > %t
 RUN: llvm-objcopy -R .text -R s0 -R s1 -R s2 -R s3 -R s4 -R s5 -R s6 %t.0 %t2
 RUN: llvm-objcopy -add-section=.s0=%t -add-section=.s1=%t -add-section=.s2=%t %t2 %t2
Index: test/tools/llvm-symbolizer/pdb/pdb.test
===================================================================
--- test/tools/llvm-symbolizer/pdb/pdb.test
+++ test/tools/llvm-symbolizer/pdb/pdb.test
@@ -9,7 +9,7 @@
 --relative-address.
 
 RUN: grep '^ADDR:' %s | sed -s 's/ADDR: //' \
-RUN: 	| "%python" -c 'import sys;print("\n".join([hex(int(x, 16) - 0x400000) for x in sys.stdin]))' \
+RUN: 	| %python -c 'import sys;print("\n".join([hex(int(x, 16) - 0x400000) for x in sys.stdin]))' \
 RUN:	| llvm-symbolizer -obj="%p/Inputs/test.exe" -demangle=false --relative-address \
 RUN:    | FileCheck %s --check-prefix=CHECK-NO-DEMANGLE
 
Index: test/tools/llvm-symbolizer/ppc64.test
===================================================================
--- test/tools/llvm-symbolizer/ppc64.test
+++ test/tools/llvm-symbolizer/ppc64.test
@@ -4,7 +4,7 @@
 int bar() { return foo(); }
 int _start() { return bar(); }
 
-RUN: "%python" -c "print('0x1000014c\n0x1000018c\n0x100001cc')" | llvm-symbolizer -obj=%p/Inputs/ppc64 | FileCheck %s
+RUN: %python -c "print('0x1000014c\n0x1000018c\n0x100001cc')" | llvm-symbolizer -obj=%p/Inputs/ppc64 | FileCheck %s
 
 CHECK: foo
 CHECK: bar
Index: utils/lit/lit/llvm/config.py
===================================================================
--- utils/lit/lit/llvm/config.py
+++ utils/lit/lit/llvm/config.py
@@ -299,7 +299,8 @@
                 'count'), verbatim=True, unresolved='fatal'),
             ToolSubst(r'\| \bnot\b', command=FindTool('not'), verbatim=True, unresolved='fatal')]
 
-        self.config.substitutions.append(('%python', sys.executable))
+        self.config.substitutions.append(('%python', "'%s'" % (sys.executable)))
+
         self.add_tool_substitutions(
             tool_patterns, [self.config.llvm_tools_dir])
 
Index: utils/lit/tests/Inputs/shtest-env/lit.cfg
===================================================================
--- utils/lit/tests/Inputs/shtest-env/lit.cfg
+++ utils/lit/tests/Inputs/shtest-env/lit.cfg
@@ -6,4 +6,4 @@
 config.test_exec_root = None
 config.environment['FOO'] = '1'
 config.environment['BAR'] = '2'
-config.substitutions.append(('%{python}', sys.executable))
+config.substitutions.append(('%{python}', "'%s'" % (sys.executable)))
Index: utils/lit/tests/Inputs/shtest-format/external_shell/fail_with_bad_encoding.txt
===================================================================
--- utils/lit/tests/Inputs/shtest-format/external_shell/fail_with_bad_encoding.txt
+++ utils/lit/tests/Inputs/shtest-format/external_shell/fail_with_bad_encoding.txt
@@ -1,5 +1,5 @@
 # Run a command that fails with error on stdout.
 #
-# RUN: "%{python}" %S/write-bad-encoding.py
+# RUN: %{python} %S/write-bad-encoding.py
 # RUN: false
 
Index: utils/lit/tests/Inputs/shtest-format/lit.cfg
===================================================================
--- utils/lit/tests/Inputs/shtest-format/lit.cfg
+++ utils/lit/tests/Inputs/shtest-format/lit.cfg
@@ -6,4 +6,4 @@
 config.test_exec_root = None
 config.target_triple = 'x86_64-unknown-unknown'
 config.available_features.add('a-present-feature')
-config.substitutions.append(('%{python}', sys.executable))
+config.substitutions.append(('%{python}', "'%s'" % (sys.executable)))
Index: utils/lit/tests/Inputs/shtest-shell/dev-null.txt
===================================================================
--- utils/lit/tests/Inputs/shtest-shell/dev-null.txt
+++ utils/lit/tests/Inputs/shtest-shell/dev-null.txt
@@ -1,14 +1,14 @@
 # Check handling of /dev/null in command line options
 # On windows, it should be redirected to a temp file.
 #
-# RUN: "%{python}" %S/check_args.py --my_arg /dev/null | FileCheck %s --check-prefix=CHECK1
+# RUN: %{python} %S/check_args.py --my_arg /dev/null | FileCheck %s --check-prefix=CHECK1
 # CHECK1: OK
 
-# RUN: "%{python}" %S/check_args.py --my_arg=/dev/null | FileCheck %s --check-prefix=CHECK2
+# RUN: %{python} %S/check_args.py --my_arg=/dev/null | FileCheck %s --check-prefix=CHECK2
 # CHECK2: OK
 
-# RUN: "%{python}" %S/check_args.py -a /dev/null | FileCheck %s --check-prefix=CHECK3
+# RUN: %{python} %S/check_args.py -a /dev/null | FileCheck %s --check-prefix=CHECK3
 # CHECK3: OK
 
-# RUN: "%{python}" %S/check_args.py -a=/dev/null | FileCheck %s --check-prefix=CHECK4
+# RUN: %{python} %S/check_args.py -a=/dev/null | FileCheck %s --check-prefix=CHECK4
 # CHECK4: OK
Index: utils/lit/tests/Inputs/shtest-shell/lit.cfg
===================================================================
--- utils/lit/tests/Inputs/shtest-shell/lit.cfg
+++ utils/lit/tests/Inputs/shtest-shell/lit.cfg
@@ -4,4 +4,4 @@
 config.test_format = lit.formats.ShTest()
 config.test_source_root = None
 config.test_exec_root = None
-config.substitutions.append(('%{python}', sys.executable))
+config.substitutions.append(('%{python}', "'%s'" % (sys.executable)))
Index: utils/lit/tests/Inputs/shtest-shell/redirects.txt
===================================================================
--- utils/lit/tests/Inputs/shtest-shell/redirects.txt
+++ utils/lit/tests/Inputs/shtest-shell/redirects.txt
@@ -17,13 +17,13 @@
 # Check stderr redirect (2> and 2>>).
 #
 # RUN: echo "not-present" > %t.stderr-write
-# RUN: "%{python}" %S/write-to-stderr.py 2> %t.stderr-write
+# RUN: %{python} %S/write-to-stderr.py 2> %t.stderr-write
 # RUN: FileCheck --check-prefix=STDERR-WRITE < %t.stderr-write %s
 #
 # STDERR-WRITE-NOT: not-present
 # STDERR-WRITE: a line on stderr
 #
-# RUN: "%{python}" %S/write-to-stderr.py 2>> %t.stderr-write
+# RUN: %{python} %S/write-to-stderr.py 2>> %t.stderr-write
 # RUN: FileCheck --check-prefix=STDERR-APPEND < %t.stderr-write %s
 #
 # STDERR-APPEND: a line on stderr
@@ -33,7 +33,7 @@
 # Check combined redirect (&>).
 #
 # RUN: echo "not-present" > %t.combined
-# RUN: "%{python}" %S/write-to-stdout-and-stderr.py &> %t.combined
+# RUN: %{python} %S/write-to-stdout-and-stderr.py &> %t.combined
 # RUN: FileCheck --check-prefix=COMBINED-WRITE < %t.combined %s
 #
 # COMBINED-WRITE-NOT: not-present
Index: utils/lit/tests/Inputs/shtest-shell/valid-shell.txt
===================================================================
--- utils/lit/tests/Inputs/shtest-shell/valid-shell.txt
+++ utils/lit/tests/Inputs/shtest-shell/valid-shell.txt
@@ -2,13 +2,13 @@
 # Check force remove commands success whether the file does or doesn't exist.
 #
 # RUN: rm -f %t.write
-# RUN: "%{python}" %S/check_path.py file %t.write > %t.out
+# RUN: %{python} %S/check_path.py file %t.write > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-FILE < %t.out %s
 # RUN: echo "create a temp file" > %t.write
-# RUN: "%{python}" %S/check_path.py file %t.write > %t.out
+# RUN: %{python} %S/check_path.py file %t.write > %t.out
 # RUN: FileCheck --check-prefix=FILE-EXIST < %t.out %s
 # RUN: rm -f %t.write
-# RUN: "%{python}" %S/check_path.py file %t.write > %t.out
+# RUN: %{python} %S/check_path.py file %t.write > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-FILE < %t.out %s
 #
 # REMOVE-FILE: False
@@ -19,14 +19,14 @@
 #
 # Check the mkdir command with -p option.
 # RUN: rm -f -r %T/test
-# RUN: "%{python}" %S/check_path.py dir %T/test > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-PARENT-DIR < %t.out %s
 # RUN: mkdir -p %T/test
-# RUN: "%{python}" %S/check_path.py dir %T/test > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test > %t.out
 # RUN: FileCheck --check-prefix=MAKE-PARENT-DIR < %t.out %s
 # RUN: rm -f %T/test || true
 # RUN: rm -f -r %T/test
-# RUN: "%{python}" %S/check_path.py dir %T/test > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-PARENT-DIR < %t.out %s
 #
 # MAKE-PARENT-DIR: True
@@ -36,13 +36,13 @@
 #
 # RUN: rm -rf %T/test1
 # RUN: mkdir %T/test1
-# RUN: "%{python}" %S/check_path.py dir %T/test1 > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test1 > %t.out
 # RUN: FileCheck --check-prefix=MAKE-DIR < %t.out %s
 # RUN: cd %T/test1 && mkdir foo
-# RUN: "%{python}" %S/check_path.py dir %T/test1 > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test1 > %t.out
 # RUN: FileCheck --check-prefix=MAKE-DIR < %t.out %s
 # RUN: cd %T && rm -rf %T/test1
-# RUN: "%{python}" %S/check_path.py dir %T/test1 > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test1 > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-DIR < %t.out %s
 #
 # MAKE-DIR: True
@@ -52,16 +52,16 @@
 #
 # RUN: rm -rf %T/test
 # RUN: mkdir -p %T/test/test1 %T/test/test2
-# RUN: "%{python}" %S/check_path.py dir %T/test %T/test/test1 %T/test/test2 > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test %T/test/test1 %T/test/test2 > %t.out
 # RUN: FileCheck --check-prefix=DIRS-EXIST < %t.out %s
 # RUN: mkdir %T/test || true
 # RUN: echo "create a temp file" > %T/test/temp.write
 # RUN: echo "create a temp1 file" > %T/test/test1/temp1.write
 # RUN: echo "create a temp2 file" > %T/test/test2/temp2.write
-# RUN: "%{python}" %S/check_path.py file %T/test/temp.write %T/test/test1/temp1.write %T/test/test2/temp2.write> %t.out
+# RUN: %{python} %S/check_path.py file %T/test/temp.write %T/test/test1/temp1.write %T/test/test2/temp2.write> %t.out
 # RUN: FileCheck --check-prefix=FILES-EXIST < %t.out %s
 # RUN: rm -r -f %T/*
-# RUN: "%{python}" %S/check_path.py dir %T/test > %t.out
+# RUN: %{python} %S/check_path.py dir %T/test > %t.out
 # RUN: FileCheck --check-prefix=REMOVE-ALL < %t.out %s
 #
 # DIRS-EXIST: True
@@ -92,7 +92,7 @@
 # RUN: mkdir -p %T/testCat
 # RUN: echo "abcdefgh" > %T/testCat/temp.write
 # RUN: cat %T/testCat/temp.write > %T/testCat/tempcat.write
-# RUN: "%{python}" %S/check_path.py file %T/testCat/tempcat.write > %T/testCat/path.out
+# RUN: %{python} %S/check_path.py file %T/testCat/tempcat.write > %T/testCat/path.out
 # RUN: FileCheck --check-prefix=FILE-EXISTS < %T/testCat/path.out %s
 # RUN: FileCheck --check-prefix=CAT-OUTPUT < %T/testCat/tempcat.write %s
 # FILE-EXISTS: True
@@ -106,7 +106,7 @@
 # RUN: echo "efghijkl" > %T/testCat/temp2.write
 # RUN: echo "mnopqrst" > %T/testCat/temp3.write
 # RUN: cat %T/testCat/temp1.write %T/testCat/temp2.write %T/testCat/temp3.write > %T/testCat/tempmulticat.write
-# RUN: "%{python}" %S/check_path.py file %T/testCat/tempmulticat.write > %T/testCat/path.out
+# RUN: %{python} %S/check_path.py file %T/testCat/tempmulticat.write > %T/testCat/path.out
 # RUN: FileCheck --check-prefix=MULTI-FILE-EXISTS < %T/testCat/path.out %s
 # RUN: FileCheck --check-prefix=MULTI-CAT-OUTPUT < %T/testCat/tempmulticat.write %s
 # MULTI-FILE-EXISTS: True
Index: utils/lit/tests/Inputs/shtest-timeout/lit.cfg
===================================================================
--- utils/lit/tests/Inputs/shtest-timeout/lit.cfg
+++ utils/lit/tests/Inputs/shtest-timeout/lit.cfg
@@ -29,4 +29,4 @@
 config.target_triple = '(unused)'
 src_root = os.path.join(config.test_source_root, '..')
 config.environment['PYTHONPATH'] = src_root
-config.substitutions.append(('%{python}', sys.executable))
+config.substitutions.append(('%{python}', "'%s'" % (sys.executable)))
Index: utils/lit/tests/lit.cfg
===================================================================
--- utils/lit/tests/lit.cfg
+++ utils/lit/tests/lit.cfg
@@ -40,7 +40,8 @@
             src_root, 'tests', 'Inputs')))
 config.substitutions.append(('%{lit}', "%%{python} %s" % (
             os.path.join(lit_path, 'lit.py'),)))
-config.substitutions.append(('%{python}', sys.executable))
+config.substitutions.append(('%{python}', "'%s'" % (sys.executable)))
+
 
 # Enable coverage.py reporting, assuming the coverage module has been installed
 # and sitecustomize.py in the virtualenv has been modified appropriately.