diff --git a/bolt/test/AArch64/data-at-0-offset.c b/bolt/test/AArch64/data-at-0-offset.c
index e0c689a19bedd..01248a637d393 100644
--- a/bolt/test/AArch64/data-at-0-offset.c
+++ b/bolt/test/AArch64/data-at-0-offset.c
@@ -1,4 +1,4 @@
-// RUN: %clang %cflags -O2 -fPIE -Wl,-q -pie  %s -o %t.exe
+// RUN: %clang %cflags -O2 -fPIE -std=gnu99 -Wl,-q -pie  %s -o %t.exe
 // RUN: llvm-bolt %t.exe -o %t.bolt 2>&1 | FileCheck %s
 // CHECK-NOT: BOLT-WARNING: unable to disassemble instruction at offset
 
diff --git a/bolt/test/AArch64/double_jump.cpp b/bolt/test/AArch64/double_jump.cpp
index d82c4e4bb8dad..7bbc67f1af880 100644
--- a/bolt/test/AArch64/double_jump.cpp
+++ b/bolt/test/AArch64/double_jump.cpp
@@ -1,6 +1,6 @@
 // A contrived example to test the double jump removal peephole.
 
-// RUN: %clang %cflags -O0 %s -o %t.exe
+// RUN: %clangxx %cxxflags -O0 %s -o %t.exe
 // RUN: llvm-bolt %t.exe -o %t.bolt --peepholes=double-jumps | \
 // RUN:   FileCheck %s -check-prefix=CHECKBOLT
 // RUN: llvm-objdump --no-print-imm-hex -d %t.bolt | FileCheck %s
diff --git a/bolt/test/R_ABS.pic.lld.cpp b/bolt/test/R_ABS.pic.lld.cpp
index b1396209567e2..df6143e7763a6 100644
--- a/bolt/test/R_ABS.pic.lld.cpp
+++ b/bolt/test/R_ABS.pic.lld.cpp
@@ -6,7 +6,7 @@
  * with libc available.
  * REQUIRES: system-linux
  *
- * RUN: %clang %cflags -fPIC -shared %s -o %t.so -Wl,-q -fuse-ld=lld
+ * RUN: %clangxx %cxxflags -fPIC -shared %s -o %t.so -Wl,-q -fuse-ld=lld
  * RUN: llvm-bolt %t.so -o %t.so.bolt --relocs
  */
 
diff --git a/bolt/test/X86/double-jump.test b/bolt/test/X86/double-jump.test
index 791872a2b4f89..424747c4e140b 100644
--- a/bolt/test/X86/double-jump.test
+++ b/bolt/test/X86/double-jump.test
@@ -4,7 +4,7 @@
 ## correctly on Windows e.g. subshell execution
 REQUIRES: shell
 
-RUN: %clang %cflags %p/Inputs/double_jump.cpp -o %t.exe
+RUN: %clangxx %cxxflags %p/Inputs/double_jump.cpp -o %t.exe
 RUN: (llvm-bolt %t.exe --peepholes=double-jumps \
 RUN:   --eliminate-unreachable -o %t 2>&1 \
 RUN:   && llvm-objdump -d %t --print-imm-hex --no-show-raw-insn) | FileCheck %s
diff --git a/bolt/test/X86/dwarf5-df-inlined-subroutine-gc-sections-range.test b/bolt/test/X86/dwarf5-df-inlined-subroutine-gc-sections-range.test
index 3132208475bd7..9082a8b6a4957 100644
--- a/bolt/test/X86/dwarf5-df-inlined-subroutine-gc-sections-range.test
+++ b/bolt/test/X86/dwarf5-df-inlined-subroutine-gc-sections-range.test
@@ -6,7 +6,7 @@
 ; RUN: -split-dwarf-file=main.dwo -o main.o
 ; RUN: llvm-mc -dwarf-version=5 -filetype=obj -triple x86_64-unknown-linux %p/Inputs/dwarf5-df-inlined-subroutine-gc-sections-range-helper.s \
 ; RUN: -split-dwarf-file=helper.dwo -o helper.o
-; RUN: %clang --target=x86_64-pc-linux -fuse-ld=lld -Wl,-gc-sections -Wl,-q -gdwarf-5 -gsplit-dwarf=split main.o helper.o -o main.exe
+; RUN: %clang -fuse-ld=lld -Wl,-gc-sections -Wl,-q -gdwarf-5 -gsplit-dwarf=split main.o helper.o -o main.exe
 ; RUN: llvm-bolt main.exe -o main.exe.bolt --update-debug-sections
 ; RUN: llvm-dwarfdump --debug-addr main.exe > log.txt
 ; RUN: llvm-dwarfdump --debug-rnglists --verbose --show-form main.dwo >> log.txt
diff --git a/bolt/test/X86/jmp-optimization.test b/bolt/test/X86/jmp-optimization.test
index a98be11573416..f969578a5b1a0 100644
--- a/bolt/test/X86/jmp-optimization.test
+++ b/bolt/test/X86/jmp-optimization.test
@@ -4,7 +4,7 @@
 ## correctly on Windows e.g. unsupported parameter expansion
 REQUIRES: shell
 
-RUN: %clang %cflags -O2 %S/Inputs/jmp_opt{,2,3}.cpp -o %t
+RUN: %clangxx %cxxflags -O2 %S/Inputs/jmp_opt{,2,3}.cpp -o %t
 RUN: llvm-bolt -inline-small-functions %t -o %t.bolt
 RUN: llvm-objdump -d %t.bolt --print-imm-hex | FileCheck %s
 
diff --git a/bolt/test/X86/match-functions-with-call-graph.test b/bolt/test/X86/match-functions-with-call-graph.test
index e826c57f35312..fe073736865e8 100644
--- a/bolt/test/X86/match-functions-with-call-graph.test
+++ b/bolt/test/X86/match-functions-with-call-graph.test
@@ -2,7 +2,7 @@
 
 # REQUIRES: system-linux
 # RUN: split-file %s %t
-# RUN: %clang %cflags %t/main.cpp -o %t.exe -Wl,-q -nostdlib
+# RUN: %clangxx %cxxflags %t/main.cpp -o %t.exe -Wl,-q -nostdlib
 # RUN: llvm-bolt %t.exe -o %t.out --data %t/yaml --profile-ignore-hash -v=1 \
 # RUN:   --dyno-stats --print-cfg --infer-stale-profile=1 --match-with-call-graph 2>&1 | FileCheck %s
 
diff --git a/bolt/test/pie.test b/bolt/test/pie.test
index 7c833c09bbf09..b5c414500c930 100644
--- a/bolt/test/pie.test
+++ b/bolt/test/pie.test
@@ -4,7 +4,7 @@
 ## on Linux systems where the host triple matches the target.
 REQUIRES: system-linux
 
-RUN: %clang %cflags -fPIC -pie %p/Inputs/jump_table_icp.cpp -o %t
+RUN: %clangxx %cxxflags -fPIC -pie %p/Inputs/jump_table_icp.cpp -o %t
 RUN: llvm-bolt %t -o %t.null 2>&1 | FileCheck %s
 
 CHECK: BOLT-INFO: shared object or position-independent executable detected
diff --git a/bolt/test/runtime/X86/instrumentation-indirect.c b/bolt/test/runtime/X86/instrumentation-indirect.c
index 5f02a6020c74b..634240c369823 100644
--- a/bolt/test/runtime/X86/instrumentation-indirect.c
+++ b/bolt/test/runtime/X86/instrumentation-indirect.c
@@ -38,7 +38,7 @@ int main(int argc, char **argv) {
 /*
 REQUIRES: system-linux,bolt-runtime,lit-max-individual-test-time
 
-RUN: %clang %cflags %s -o %t.exe -Wl,-q -pie -fpie
+RUN: %clang %cflags -D_GNU_SOURCE %s -o %t.exe -Wl,-q -pie -fpie
 
 RUN: llvm-bolt %t.exe --instrument --instrumentation-file=%t.fdata \
 RUN:   --instrumentation-wait-forks=1 --conservative-instrumentation \
diff --git a/bolt/test/runtime/bolt-reserved.cpp b/bolt/test/runtime/bolt-reserved.cpp
index c88b1e284d074..2ebadfea5fa02 100644
--- a/bolt/test/runtime/bolt-reserved.cpp
+++ b/bolt/test/runtime/bolt-reserved.cpp
@@ -5,7 +5,7 @@
  * new sections.
  */
 
-// RUN: %clang %s -o %t.exe -Wl,-q
+// RUN: %clangxx %s -o %t.exe -Wl,-q
 // RUN: llvm-bolt %t.exe -o %t.bolt.exe 2>&1 | FileCheck %s
 // RUN: %t.bolt.exe
 
@@ -16,7 +16,7 @@
  * not enough for allocating new sections.
  */
 
-// RUN: %clang %s -o %t.tiny.exe -Wl,--no-eh-frame-hdr -Wl,-q -DTINY
+// RUN: %clangxx %s -o %t.tiny.exe -Wl,--no-eh-frame-hdr -Wl,-q -DTINY
 // RUN: not llvm-bolt %t.tiny.exe -o %t.tiny.bolt.exe 2>&1 | \
 // RUN:   FileCheck %s --check-prefix=CHECK-TINY