diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f394bd403..39944553b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -61,7 +61,7 @@ jobs:
         if: matrix.regression-tests
         with:
           path: tests/regression/test_data
-          key: test-data-llvm${{ matrix.llvm }}-${{ hashFiles('tests/regression/test_specs/*') }}
+          key: test-data-llvm${{ matrix.llvm }}-bc-${{ hashFiles('tests/regression/test_specs/*') }}
 
       # Download kernel sources:
       # - if test_data is cached, we only need the kernel for unit tests
@@ -113,4 +113,4 @@ jobs:
         uses: actions/cache@v4
         with:
           path: tests/regression/test_data
-          key: test-data-llvm${{ matrix.llvm }}-${{ hashFiles('tests/regression/test_specs/*') }}
+          key: test-data-llvm${{ matrix.llvm }}-bc-${{ hashFiles('tests/regression/test_specs/*') }}
diff --git a/.gitignore b/.gitignore
index 6bde2226b..c46f59067 100644
--- a/.gitignore
+++ b/.gitignore
@@ -105,7 +105,7 @@ cmake-build-debug/
 .vscode/
 
 # Temporary files from regression tests. Used for debugging purposes only.
-*.ll
+*.bc
 *.smt2
 *.pdf
 
diff --git a/diffkemp/building/cc_wrapper/cc_wrapper.py b/diffkemp/building/cc_wrapper/cc_wrapper.py
index 2eecb9edb..ef8b88248 100755
--- a/diffkemp/building/cc_wrapper/cc_wrapper.py
+++ b/diffkemp/building/cc_wrapper/cc_wrapper.py
@@ -134,15 +134,15 @@ def wrapper(argv):
         contains_source = contains_source or is_source_file
         if index > 1 and argv[index - 1] == "-o":
             if is_object_file and not linking:
-                # Compiling to object file: swap .o with .ll
-                arg = arg.rsplit(".", 1)[0] + ".ll"
+                # Compiling to object file: swap .o with .bc
+                arg = arg.rsplit(".", 1)[0] + ".bc"
             if not is_object_file and linking:
-                # Linking: add a .llw suffix (LLVM IR whole)
-                arg = arg + ".llw"
+                # Linking: add a .bcw suffix (LLVM IR whole)
+                arg = arg + ".bcw"
             output_file = arg
         elif is_object_file and linking:
-            # Input to linking phase: change suffix to .ll
-            arg = arg.rsplit(".", 1)[0] + ".ll"
+            # Input to linking phase: change suffix to .bc
+            arg = arg.rsplit(".", 1)[0] + ".bc"
             clang = llvm_link
         elif is_source_file and linking:
             # Mark as linking with sources to detect hybrid mode
@@ -153,16 +153,16 @@ def wrapper(argv):
         # Compile/link mode with object files detected
         # Drop object files and revert to normal compile/link mode
         clang = old_clang
-        clang_argv = [arg for arg in clang_argv if not arg.endswith(".ll")]
+        clang_argv = [arg for arg in clang_argv if not arg.endswith(".bc")]
 
-    # Do not continue if output is not .ll or .llw
+    # Do not continue if output is not .bc or .bcw
     # Note: this means that this is neither compilation nor linking
-    if (output_file is not None and not output_file.endswith(".ll") and
-            not output_file.endswith(".llw")):
+    if (output_file is not None and not output_file.endswith(".bc") and
+            not output_file.endswith(".bcw")):
         return 0
 
     # Do not run clang on conftest files
-    if output_file in ["conftest.ll", "conftest.llw"] or "conftest.c" in argv:
+    if output_file in ["conftest.bc", "conftest.bcw"] or "conftest.c" in argv:
         return 0
 
     # Not compiling C source file
@@ -176,7 +176,7 @@ def wrapper(argv):
     elif not linking:
         # Compiling to default output file
         db.extend(["o:" + os.path.join(os.getcwd(),
-                                       arg.rsplit(".", 1)[0] + ".ll")
+                                       arg.rsplit(".", 1)[0] + ".bc")
                    for arg in clang_argv if not arg.endswith(".c")])
 
     # Analyze and modify parameters for clang (phase 2)
@@ -192,7 +192,7 @@ def wrapper(argv):
     else:
         # Keep only arguments with input files (and llvm-link itself)
         clang_argv = [arg for arg in clang_argv if arg == clang or
-                      arg.endswith(".ll") or arg.endswith(".llw") or
+                      arg.endswith(".bc") or arg.endswith(".bcw") or
                       arg == "-o"]
         # Remove non-existent files
         # Note: these might have been e.g. generated from assembly
diff --git a/diffkemp/llvm_ir/compiler.py b/diffkemp/llvm_ir/compiler.py
index 8e351d271..e67e35a85 100644
--- a/diffkemp/llvm_ir/compiler.py
+++ b/diffkemp/llvm_ir/compiler.py
@@ -8,7 +8,7 @@
 def get_clang_default_options(default_optim=True):
     """Returns clang options for compiling c files to LLVM IR.
     :param default_optim: By default adds also optimization flags."""
-    opts = ["-S", "-emit-llvm", "-g", "-fdebug-macro", "-Wno-format-security"]
+    opts = ["-c", "-emit-llvm", "-g", "-fdebug-macro", "-Wno-format-security"]
     if default_optim:
         opts.extend(["-O1", "-Xclang", "-disable-llvm-passes"])
     return opts
diff --git a/diffkemp/llvm_ir/kernel_llvm_source_builder.py b/diffkemp/llvm_ir/kernel_llvm_source_builder.py
index 6999ff751..7ff1099cb 100644
--- a/diffkemp/llvm_ir/kernel_llvm_source_builder.py
+++ b/diffkemp/llvm_ir/kernel_llvm_source_builder.py
@@ -70,7 +70,7 @@ def find_llvm_with_symbol_def(self, symbol):
                 llvm_filename = self._build_source_to_llvm(source_path)
                 if os.path.isfile(llvm_filename):
                     mod = LlvmModule(llvm_filename)
-                    if mod.has_function(symbol) or mod.has_global(symbol):
+                    if mod.has_definition(symbol):
                         break
             except BuildException:
                 pass
@@ -395,9 +395,9 @@ def _gcc_to_llvm(gcc_command):
             if param.startswith('-D"DEBUG_HASH2='):
                 param = '-D"DEBUG_HASH2=1"'
 
-            # Output name is given by replacing .c by .ll in source name
+            # Output name is given by replacing .c by .bc in source name
             if param.endswith(".c"):
-                output_file = "{}.ll".format(param[:-2])
+                output_file = "{}.bc".format(param[:-2])
 
             command.append(KernelLlvmSourceBuilder._strip_bash_quotes(param))
         if output_file is None:
@@ -414,10 +414,10 @@ def _ld_to_llvm(ld_command):
         :param ld_command: Command to convert
         :return Corresponding llvm-link command.
         """
-        command = ["llvm-link", "-S"]
+        command = ["llvm-link"]
         for param in ld_command.split():
             if param.endswith(".o"):
-                command.append("{}.ll".format(param[:-2]))
+                command.append("{}.bc".format(param[:-2]))
             elif param == "-o":
                 command.append(param)
         return command
@@ -486,8 +486,12 @@ def _get_build_object(command):
 
     @staticmethod
     def _get_build_source(command):
-        """Get name of the object file built by the command."""
-        return command[command.index("-c") + 1]
+        """
+        Get name of the source file built by the command.
+        The commands start with 'clang -c -emit-llvm' to avoid linking
+        and the source file follows '-c' later in the command.
+        """
+        return command[command.index("-c", 3) + 1]
 
     def _kbuild_object_command(self, object_file):
         """
@@ -568,7 +572,7 @@ def _build_source_to_llvm(self, source_file):
         :param source_file: C source to build
         :return: Created LLVM IR file
         """
-        llvm_file = "{}.ll".format(source_file[:-2])
+        llvm_file = "{}.bc".format(source_file[:-2])
         if (not os.path.isfile(llvm_file) or os.path.getmtime(llvm_file) <
                 os.path.getmtime(source_file)):
             cwd = os.getcwd()
@@ -627,7 +631,7 @@ def _build_kernel_mod_to_llvm(self, mod_dir, mod_name):
                         obj = self._get_build_object(c)
                         if not os.path.isfile(obj) or built:
                             check_call(c, stderr=stderr)
-            llvm_file = os.path.join(mod_dir, "{}.ll".format(file_name))
+            llvm_file = os.path.join(mod_dir, "{}.bc".format(file_name))
             opt_llvm(llvm_file)
             return llvm_file
         except CalledProcessError:
diff --git a/diffkemp/llvm_ir/llvm_module.py b/diffkemp/llvm_ir/llvm_module.py
index 01d0b45f4..bc24b7819 100644
--- a/diffkemp/llvm_ir/llvm_module.py
+++ b/diffkemp/llvm_ir/llvm_module.py
@@ -9,7 +9,9 @@
 import os
 import re
 import shutil
-from subprocess import check_call, CalledProcessError
+from subprocess import check_call, check_output
+from subprocess import CalledProcessError, PIPE, run
+
 
 # Set of standard functions that are supported, so they should not be
 # included in function collecting.
@@ -76,10 +78,10 @@ def link_modules(self, modules):
             return False
 
         if "-linked" not in self.llvm:
-            new_llvm = "{}-linked.ll".format(self.llvm[:-3])
+            new_llvm = "{}-linked.bc".format(self.llvm[:-3])
         else:
             new_llvm = self.llvm
-        link_command = ["llvm-link", "-S", self.llvm]
+        link_command = ["llvm-link", self.llvm]
         link_command.extend([m.llvm for m in link_llvm_modules])
         link_command.extend(["-o", new_llvm])
         opt_command = get_opt_command([("constmerge", "module")], new_llvm)
@@ -112,17 +114,30 @@ def find_param_var(self, param):
         name = self.llvm_module.find_param_var(param)
         return LlvmParam(name, []) if name is not None else None
 
+    def module_has(self, symtype_pattern, symbol):
+        """
+        Check if a module contains matches for a pattern.
+        Used in has_function, has_global and has_definition.
+        """
+        command = ["llvm-nm", self.llvm]
+        source_dir = os.path.dirname(self.llvm)
+        nm_out = check_output(command, cwd=source_dir)
+        pattern = re.compile(rf"{symtype_pattern} {re.escape(symbol)}",
+                             re.MULTILINE)
+        match = pattern.search(nm_out.decode())
+        return match is not None
+
     def has_function(self, fun):
         """Check if module contains a function definition."""
-        pattern = re.compile(r"^define.*@{}\(".format(fun), flags=re.MULTILINE)
-        with open(self.llvm, "r") as llvm_file:
-            return pattern.search(llvm_file.read()) is not None
+        return self.module_has("[T|t]", fun)
 
     def has_global(self, glob):
         """Check if module contains a global variable with the given name."""
-        pattern = re.compile(r"^@{}\s*=".format(glob), flags=re.MULTILINE)
-        with open(self.llvm, "r") as llvm_file:
-            return pattern.search(llvm_file.read()) is not None
+        return self.module_has("[DdBbCU]", glob)
+
+    def has_definition(self, symbol):
+        """Check if module contains a given symbol definition."""
+        return self.module_has("[DdBbCTt]", symbol)
 
     def is_declaration(self, fun):
         """
@@ -156,16 +171,21 @@ def move_to_other_root_dir(self, old_root, new_root):
         if self.llvm.startswith(old_root):
             dest_llvm = os.path.join(new_root,
                                      os.path.relpath(self.llvm, old_root))
-            # Copy the .ll file and replace all occurrences of the old root by
-            # the new root. There are usually in debug info.
-            with open(self.llvm, "r") as llvm:
-                with open(dest_llvm, "w") as llvm_new:
-                    for line in llvm.readlines():
-                        if "constant" not in line:
-                            llvm_new.write(line.replace(old_root.strip("/"),
-                                                        new_root.strip("/")))
-                        else:
-                            llvm_new.write(line)
+            # Copy the .bc file and replace all occurrences of the old root by
+            # the new root. There are usually in debug info. Use textual
+            # LLVM IR to find the paths.
+            command = ["llvm-dis", self.llvm, "-o", "-"]
+            source_dir = os.path.dirname(self.llvm)
+            output = check_output(command, cwd=source_dir).decode()
+            new_lines = []
+            for line in output.splitlines():
+                if "constant" not in line:
+                    new_lines.append(line.replace(old_root.strip("/"),
+                                                  new_root.strip("/")))
+                else:
+                    new_lines.append(line)
+            run(["llvm-as", "-o", dest_llvm], input="\n".join(new_lines),
+                stdout=PIPE, stderr=PIPE, text=True, check=True)
             self.llvm = dest_llvm
 
         if self.source and self.source.startswith(old_root):
@@ -178,18 +198,42 @@ def move_to_other_root_dir(self, old_root, new_root):
     def get_included_sources(self):
         """
         Get the list of source files that this module includes.
-        Requires debugging information.
+        Sources are extracted from the llvm-bcanalyzer output (with --dump).
+        The are located in the first METADATA_BLOCK as STRINGS.
+        The first string is the file name, second is project directory,
+        the includes follow.
         """
-        # Search for all .h files mentioned in the debug info.
-        pattern = re.compile(r"filename:\s*\"([^\"]*)\", "
-                             r"directory:\s*\"([^\"]*)\"")
+        source_dir = ''.join(os.path.split(self.llvm)[0])
+        command = ["llvm-bcanalyzer", self.llvm, "-dump"]
+        bc_out = check_output(command, cwd=source_dir)
         result = set()
-        with open(self.llvm, "r") as llvm:
-            for line in llvm.readlines():
-                s = pattern.search(line)
-                if (s and (s.group(1).endswith(".h") or
-                           s.group(1).endswith(".c"))):
-                    result.add(os.path.join(s.group(2), s.group(1)))
+        in_metadata = False
+        in_strings = False
+        root_dir = ""
+        source_file = ""
+        for line in bc_out.decode().splitlines():
+            line = line.strip()
+            if line.startswith("<METADATA_BLOCK "):
+                in_metadata = True
+            elif in_metadata and line.startswith("<STRINGS "):
+                in_strings = True
+                continue
+            if not in_strings:
+                continue
+            if line == "}":
+                break
+            # Extract paths: 1st path is source file name,
+            # 2nd is project directory
+            string = line[1:-1]
+            if not source_file:
+                source_file = string
+            elif not root_dir:
+                root_dir = string
+                # Add source file when project directory is known
+                result.add(os.path.join(root_dir, source_file))
+            elif (string.endswith(".h") or string.endswith(".c")
+                  ) and not string.startswith("/"):
+                result.add(os.path.join(root_dir, string))
         return result
 
     def get_functions_using_param(self, param):
diff --git a/diffkemp/llvm_ir/single_c_builder.py b/diffkemp/llvm_ir/single_c_builder.py
index 001ae1398..00d5efe44 100644
--- a/diffkemp/llvm_ir/single_c_builder.py
+++ b/diffkemp/llvm_ir/single_c_builder.py
@@ -22,7 +22,7 @@ def __init__(self, source_dir, c_file_name, clang="clang",
         :param default_optim: use default optimalisations flags
             and run LLVM IR simplification passes
         """
-        llvm_file_name = os.path.splitext(c_file_name)[0] + ".ll"
+        llvm_file_name = os.path.splitext(c_file_name)[0] + ".bc"
         SingleLlvmFinder.__init__(self, source_dir, llvm_file_name)
 
         self.c_file_name = c_file_name
diff --git a/diffkemp/utils.py b/diffkemp/utils.py
index bd04a442b..fdb4ac2ba 100644
--- a/diffkemp/utils.py
+++ b/diffkemp/utils.py
@@ -2,8 +2,10 @@
 import subprocess
 import re
 import sys
+from subprocess import check_output
 
-LLVM_FUNCTION_REGEX = re.compile(r"^define.*@(\w+)\(", flags=re.MULTILINE)
+LLVM_FUNCTION_REGEX = re.compile(r"^.* [T|t] ([\w|\.|\$]+)",
+                                 flags=re.MULTILINE)
 # Name of YAML output file created by diffkemp compare command.
 CMP_OUTPUT_FILE = "diffkemp-out.yaml"
 
@@ -42,7 +44,7 @@ def get_opt_command(passes, llvm_file, overwrite=True):
         pass_names = map(lambda p: p[0], passes)
         opt_command.extend(map(lambda pass_name: f"-{pass_name}", pass_names))
     if overwrite:
-        opt_command.extend(["-S", "-o", llvm_file])
+        opt_command.extend(["-o", llvm_file])
     return opt_command
 
 
@@ -96,9 +98,10 @@ def get_functions_from_llvm(llvm_files):
             sys.stderr.write(
                 f"Warning: llvm file '{llvm_filename}' does not exist\n")
             continue
-        with open(llvm_filename, 'r') as llvm_file:
-            llvm_file_content = llvm_file.read()
-            matches = LLVM_FUNCTION_REGEX.findall(llvm_file_content)
-            for match in matches:
-                functions[match] = llvm_filename
+        command = ["llvm-nm", llvm_filename]
+        source_dir = ''.join(os.path.split(llvm_filename)[0])
+        nm_out = check_output(command, cwd=source_dir)
+        matches = LLVM_FUNCTION_REGEX.findall(nm_out.decode())
+        for match in matches:
+            functions[match] = llvm_filename
     return functions
diff --git a/tests/regression/mock_source_tree.py b/tests/regression/mock_source_tree.py
index b650a3ae2..3f9e29d79 100644
--- a/tests/regression/mock_source_tree.py
+++ b/tests/regression/mock_source_tree.py
@@ -22,7 +22,7 @@ def __init__(self, source_dir, real_source_tree):
         self.real_source_tree = real_source_tree
 
     def get_module_for_symbol(self, symbol, created_before=None):
-        llvm_file = os.path.join(self.source_dir, "{}.ll".format(symbol))
+        llvm_file = os.path.join(self.source_dir, "{}.bc".format(symbol))
         src_file = os.path.join(self.source_dir, "{}.c".format(symbol))
 
         if not os.path.exists(llvm_file) and self.real_source_tree is not None:
@@ -35,7 +35,7 @@ def get_module_for_symbol(self, symbol, created_before=None):
         return LlvmModule(llvm_file, src_file)
 
     def get_kernel_module(self, mod_dir, mod_name):
-        llvm_file = os.path.join(self.source_dir, "{}.ll".format(mod_name))
+        llvm_file = os.path.join(self.source_dir, "{}.bc".format(mod_name))
 
         if not os.path.exists(llvm_file):
             assert self.real_source_tree is not None
@@ -45,7 +45,7 @@ def get_kernel_module(self, mod_dir, mod_name):
         return LlvmModule(llvm_file)
 
     def get_sysctl_module(self, sysctl):
-        llvm_file = os.path.join(self.source_dir, "{}.ll".format(sysctl))
+        llvm_file = os.path.join(self.source_dir, "{}.bc".format(sysctl))
         table_file = os.path.join(self.source_dir, "table")
 
         if not os.path.exists(llvm_file):
diff --git a/tests/testing_projects/.gitignore b/tests/testing_projects/.gitignore
index 6fb40971c..3bdcea0cc 100644
--- a/tests/testing_projects/.gitignore
+++ b/tests/testing_projects/.gitignore
@@ -1,6 +1,6 @@
 *.o
 
 # Files created by the build command
-*.ll
+*.bc
 function_list
 *.so.llw
diff --git a/tests/testing_projects/make_based/Makefile b/tests/testing_projects/make_based/Makefile
index 962343e78..257ebae38 100644
--- a/tests/testing_projects/make_based/Makefile
+++ b/tests/testing_projects/make_based/Makefile
@@ -6,10 +6,10 @@ CFLAGS = -O2 -std=c99
 
 default: file.o
 
-# Assembly files should not be compiled to `.ll`
+# Assembly files should not be compiled to `.bc`
 with-assembly: default mod.o sub.o
 
-# Compilation with linking, should be compiled to `.llw`
+# Compilation with linking, should be compiled to `.bcw`
 with-linking: default file.so
 
 # Note: mod.o (mod.S) is implicitly compiled using CC, but sub.o (sub.s)
@@ -23,4 +23,4 @@ file.so: file.o
 	$(CC) $(CFLAGS) -o $@ $^ -shared
 
 clean:
-	rm -f *.o *.ll *.so
+	rm -f *.o *.so *.bc
diff --git a/tests/testing_projects/make_based/mod.S b/tests/testing_projects/make_based/mod.S
index f54e4f34c..e7aa0d8e2 100644
--- a/tests/testing_projects/make_based/mod.S
+++ b/tests/testing_projects/make_based/mod.S
@@ -1,5 +1,5 @@
 // File for testing of building of snapshots,
-// this file should NOT be compiled to .ll and added to db file.
+// this file should NOT be compiled to .bc and added to db file.
 // Note: File was compiled from a C file, trimmed and edited.
     .text
     .p2align 4
diff --git a/tests/testing_projects/make_based/sub.s b/tests/testing_projects/make_based/sub.s
index 8354d684c..14e65a601 100644
--- a/tests/testing_projects/make_based/sub.s
+++ b/tests/testing_projects/make_based/sub.s
@@ -1,5 +1,5 @@
 # File for testing of building of snapshots,
-# this file should NOT be compiled to .ll and added to db file.
+# this file should NOT be compiled to .bc and added to db file.
 # Note: File was compiled from a C file and trimmed.
     .text
     .p2align 4
diff --git a/tests/unit_tests/build_test.py b/tests/unit_tests/build_test.py
index abd0d0569..186a5db10 100644
--- a/tests/unit_tests/build_test.py
+++ b/tests/unit_tests/build_test.py
@@ -5,6 +5,8 @@
 import pytest
 import re
 import yaml
+from subprocess import check_output
+
 
 SINGLE_C_FILE = os.path.abspath("tests/testing_projects/make_based/file.c")
 MAKE_BASED_PROJECT_DIR = os.path.abspath("tests/testing_projects/make_based")
@@ -41,11 +43,12 @@ def get_db_file_content(snapshot_dir):
 
 def get_llvm_fun_body(llvm_file, fun_name):
     """Returns body of fun_name function from llvm_file."""
-    with open(llvm_file, "r") as file:
-        content = file.read()
-        match = re.search(r"define.*@" + re.escape(fun_name) + r"[ (][^}]*",
-                          content, re.MULTILINE)
-        return match.group(0)
+    command = ["llvm-dis", llvm_file, "-o", "-"]
+    source_dir = os.path.dirname(llvm_file)
+    output = check_output(command, cwd=source_dir).decode()
+    match = re.search(r"define.*@" + re.escape(fun_name) + r"[ (][^}]*",
+                      output, re.MULTILINE)
+    return match.group(0)
 
 
 @pytest.mark.parametrize("source",
@@ -60,11 +63,11 @@ def test_build_command(source, tmp_path):
     # Snapshot should contain source file, LLVM file and file with metadata.
     output_files = os.listdir(output_dir)
     assert "file.c" in output_files
-    assert "file.ll" in output_files
+    assert "file.bc" in output_files
     assert "snapshot.yaml" in output_files
 
     # Functions from the source file should be also in the llvm file.
-    llvm_file_path = os.path.join(output_dir, "file.ll")
+    llvm_file_path = os.path.join(output_dir, "file.bc")
     llvm_fun_list = get_functions_from_llvm([llvm_file_path])
     assert "add" in llvm_fun_list
     assert "mul" in llvm_fun_list
@@ -89,14 +92,14 @@ def test_make_based_with_assembly(tmp_path):
     args = Arguments(MAKE_BASED_PROJECT_DIR, output_dir,
                      target=["with-assembly"])
     build(args)
-    # .s, .S files should not be compiled to .ll
+    # .s, .S files should not be compiled to .bc
     src_dir_files = os.listdir(MAKE_BASED_PROJECT_DIR)
-    assert "mod.ll" not in src_dir_files
-    assert "sub.ll" not in src_dir_files
+    assert "mod.bc" not in src_dir_files
+    assert "sub.bc" not in src_dir_files
     # and they should not be added to db file
     db_file_content = get_db_file_content(output_dir)
-    assert "mod.ll" not in db_file_content
-    assert "sub.ll" not in db_file_content
+    assert "mod.bc" not in db_file_content
+    assert "sub.bc" not in db_file_content
 
 
 def test_make_based_with_linking(tmp_path):
@@ -106,11 +109,11 @@ def test_make_based_with_linking(tmp_path):
                      target=["with-linking"])
     build(args)
     # When linking *.o files, appropriate .ll files
-    # should be linked with llvm-link and saved as `.llw`.
-    # Note: The .llw is not copied to snapshot dir.
-    assert "file.so.llw" in os.listdir(MAKE_BASED_PROJECT_DIR)
+    # should be linked with llvm-link and saved as `.bcw`.
+    # Note: The .bcw is not copied to snapshot dir.
+    assert "file.so.bcw" in os.listdir(MAKE_BASED_PROJECT_DIR)
     db_file_content = get_db_file_content(output_dir)
-    assert "file.so.llw" in db_file_content
+    assert "file.so.bcw" in db_file_content
 
 
 def test_build_no_opt_override(tmp_path):
@@ -122,6 +125,6 @@ def test_build_no_opt_override(tmp_path):
     # With --no-opt-override the optimization level which is written
     # in Makefile should be used, because it is -O2 the `add` function
     # should not be called from the `mul` function` (should be "inlined").
-    llvm_file_path = os.path.join(output_dir, "file.ll")
+    llvm_file_path = os.path.join(output_dir, "file.bc")
     body = get_llvm_fun_body(llvm_file_path, "mul")
     assert re.search(r"call.*@add", body) is None
diff --git a/tests/unit_tests/caching_test.py b/tests/unit_tests/caching_test.py
index ae6789ef1..4d7d30545 100644
--- a/tests/unit_tests/caching_test.py
+++ b/tests/unit_tests/caching_test.py
@@ -269,14 +269,14 @@ def test_cachability_reset_after_absorb(graph_uncachable):
 
 @pytest.fixture
 def cache_file():
-    yield SimpLLCache.CacheFile(mkdtemp(), "/test/f1/1.ll", "/test/f2/2.ll")
+    yield SimpLLCache.CacheFile(mkdtemp(), "/test/f1/1.bc", "/test/f2/2.bc")
 
 
 def test_cache_file_init(cache_file):
     """Tests the constructor of the SimpLLCache.CacheFile class."""
-    assert cache_file.left_module == "/test/f1/1.ll"
-    assert cache_file.right_module == "/test/f2/2.ll"
-    assert cache_file.filename.endswith("..$f1$1.ll:..$f2$2.ll")
+    assert cache_file.left_module == "/test/f1/1.bc"
+    assert cache_file.right_module == "/test/f2/2.bc"
+    assert cache_file.filename.endswith("..$f1$1.bc:..$f2$2.bc")
 
 
 def test_cache_file_add_function_pairs(cache_file):
@@ -302,27 +302,27 @@ def simpll_cache():
 def vertices():
     yield [ComparisonGraph.Vertex(dup("f"),
                                   Result.Kind.EQUAL,
-                                  ("/test/f1/1.ll", "/test/f2/2.ll")),
+                                  ("/test/f1/1.bc", "/test/f2/2.bc")),
            ComparisonGraph.Vertex(dup("h"),
                                   Result.Kind.NOT_EQUAL,
-                                  ("/test/f1/1.ll", "/test/f2/3.ll")),
+                                  ("/test/f1/1.bc", "/test/f2/3.bc")),
            ComparisonGraph.Vertex(dup("g"),
                                   Result.Kind.NOT_EQUAL,
-                                  ("/test/f1/1.ll", "/test/f2/2.ll"))]
+                                  ("/test/f1/1.bc", "/test/f2/2.bc"))]
 
 
 def test_simpll_cache_update(simpll_cache, vertices):
     """Tests updating of a SimpLL cache with vertices from a graph."""
     simpll_cache.update(vertices)
     assert os.path.exists(os.path.join(simpll_cache.directory,
-                                       "..$f1$1.ll:..$f2$2.ll"))
+                                       "..$f1$1.bc:..$f2$2.bc"))
     assert os.path.exists(os.path.join(simpll_cache.directory,
-                                       "..$f1$1.ll:..$f2$3.ll"))
+                                       "..$f1$1.bc:..$f2$3.bc"))
     with open(os.path.join(simpll_cache.directory,
-                           "..$f1$1.ll:..$f2$2.ll"), "r") as file:
+                           "..$f1$1.bc:..$f2$2.bc"), "r") as file:
         assert file.readlines() == ["f:f\n", "g:g\n"]
     with open(os.path.join(simpll_cache.directory,
-                           "..$f1$1.ll:..$f2$3.ll"), "r") as file:
+                           "..$f1$1.bc:..$f2$3.bc"), "r") as file:
         assert file.readlines() == ["h:h\n"]
 
 
diff --git a/tests/unit_tests/kernel_llvm_source_builder_test.py b/tests/unit_tests/kernel_llvm_source_builder_test.py
index 232025d46..bf079af7d 100644
--- a/tests/unit_tests/kernel_llvm_source_builder_test.py
+++ b/tests/unit_tests/kernel_llvm_source_builder_test.py
@@ -38,13 +38,13 @@ def test_find_llvm_with_symbol_def(builder):
     Test building LLVM module from a source containing a function definition.
     """
     llvm_file = builder.find_llvm_with_symbol_def("__alloc_workqueue_key")
-    assert llvm_file == os.path.join(builder.source_dir, "kernel/workqueue.ll")
+    assert llvm_file == os.path.join(builder.source_dir, "kernel/workqueue.bc")
 
 
 def test_find_llvm_with_symbol_use(builder):
     """Test finding sources using a global variable."""
     srcs = builder.find_llvm_with_symbol_use("net_ratelimit_state")
-    assert srcs == {os.path.join(builder.source_dir, "net/core/utils.ll")}
+    assert srcs == {os.path.join(builder.source_dir, "net/core/utils.bc")}
 
 
 def test_build_cscope_database(builder):
@@ -97,7 +97,7 @@ def test_kbuild_module_commands(builder):
 def test_build_src_to_llvm(builder):
     """Building single object into LLVM."""
     llvm_file = builder._build_source_to_llvm("sound/core/init.c")
-    assert (llvm_file == "sound/core/init.ll")
+    assert (llvm_file == "sound/core/init.bc")
     assert os.path.isfile(os.path.join(builder.source_dir, llvm_file))
 
 
@@ -110,7 +110,7 @@ def test_build_src_to_llvm_fail(builder):
 def test_build_mod_to_llvm(builder):
     """Test building kernel module into LLVM"""
     mod_file = os.path.join(builder.source_dir,
-                            "drivers/firewire/firewire-sbp2.ll")
+                            "drivers/firewire/firewire-sbp2.bc")
     if os.path.isfile(mod_file):
         os.unlink(mod_file)
     builder._build_kernel_mod_to_llvm("drivers/firewire", "firewire-sbp2")
diff --git a/tests/unit_tests/kernel_module_test.py b/tests/unit_tests/kernel_module_test.py
index 3f7857ccb..5150ae254 100644
--- a/tests/unit_tests/kernel_module_test.py
+++ b/tests/unit_tests/kernel_module_test.py
@@ -10,6 +10,7 @@
 import pytest
 import shutil
 import tempfile
+from subprocess import check_output
 
 
 @pytest.fixture
@@ -84,14 +85,16 @@ def test_move_to_other_root_dir(source):
     # Check that source (C and LLVM) files have been moved.
     mod.move_to_other_root_dir(os.path.abspath("kernel/linux-3.10.0-957.el7"),
                                tmp)
-    assert os.path.isfile(os.path.join(tmp, "sound/core/init.ll"))
+    assert os.path.isfile(os.path.join(tmp, "sound/core/init.bc"))
 
     # Check that the llvm file does not contain the original directory.
-    assert mod.llvm == os.path.join(tmp, "sound/core/init.ll")
-    with open(mod.llvm, "r") as llvm:
-        for line in llvm.readlines():
-            assert ("constant" in line or
-                    "kernel/linux-3.10.0-957.el7" not in line)
+    assert mod.llvm == os.path.join(tmp, "sound/core/init.bc")
+    command = ["llvm-dis", mod.llvm, "-o", "-"]
+    source_dir = os.path.dirname(mod.llvm)
+    output = check_output(command, cwd=source_dir).decode()
+    for line in output.splitlines():
+        assert ("constant" in line or
+                "kernel/linux-3.10.0-957.el7" not in line)
 
     shutil.rmtree(tmp)
 
diff --git a/tests/unit_tests/kernel_source_tree_test.py b/tests/unit_tests/kernel_source_tree_test.py
index 2677ac4e0..74da09746 100644
--- a/tests/unit_tests/kernel_source_tree_test.py
+++ b/tests/unit_tests/kernel_source_tree_test.py
@@ -18,10 +18,10 @@ def source():
 
 @pytest.mark.parametrize("name, llvm_file, table", [
     ("net.core.message_burst",
-     "net/core/sysctl_net_core.ll",
+     "net/core/sysctl_net_core.bc",
      "net_core_table"),
     ("kernel.usermodehelper.bset",
-     "kernel/kmod.ll",
+     "kernel/kmod.bc",
      "usermodehelper_table")
 ])
 def test_get_sysctl_module(source, name, llvm_file, table):
diff --git a/tests/unit_tests/snapshot_test.py b/tests/unit_tests/snapshot_test.py
index fe8304167..d556281d0 100644
--- a/tests/unit_tests/snapshot_test.py
+++ b/tests/unit_tests/snapshot_test.py
@@ -51,11 +51,11 @@ def test_load_snapshot_from_dir_functions():
           list_kind: function
           list:
           - glob_var: null
-            llvm: net/core/skbuff.ll
+            llvm: net/core/skbuff.bc
             name: ___pskb_trim
             tag: null
           - glob_var: null
-            llvm: mm/page_alloc.ll
+            llvm: mm/page_alloc.bc
             name: __alloc_pages_nodemask
             tag: null
           llvm_source_finder:
@@ -87,10 +87,10 @@ def test_load_snapshot_from_dir_functions():
             assert f.tag is None
             if name == "___pskb_trim":
                 assert os.path.abspath(f.mod.llvm) == snap_dir + \
-                       "/net/core/skbuff.ll"
+                       "/net/core/skbuff.bc"
             elif name == "__alloc_pages_nodemask":
                 assert os.path.abspath(f.mod.llvm) == snap_dir + \
-                       "/mm/page_alloc.ll"
+                       "/mm/page_alloc.bc"
 
 
 def test_load_snapshot_from_dir_sysctls():
@@ -111,13 +111,13 @@ def test_load_snapshot_from_dir_sysctls():
           list:
           - functions:
             - glob_var: null
-              llvm: kernel/sched/fair.ll
+              llvm: kernel/sched/fair.bc
               name: sched_proc_update_handler
               tag: proc handler
             sysctl: kernel.sched_latency_ns
           - functions:
             - glob_var: null
-              llvm: kernel/sysctl.ll
+              llvm: kernel/sysctl.bc
               name: proc_dointvec_minmax
               tag: proc handler
             sysctl: kernel.timer_migration
@@ -145,12 +145,12 @@ def test_load_snapshot_from_dir_sysctls():
                 assert g.functions.keys() == {"sched_proc_update_handler"}
                 f = g.functions["sched_proc_update_handler"]
                 assert os.path.abspath(f.mod.llvm) == snap_dir + \
-                    "/kernel/sched/fair.ll"
+                    "/kernel/sched/fair.bc"
             elif name == "kernel.timer_migration":
                 assert g.functions.keys() == {"proc_dointvec_minmax"}
                 f = g.functions["proc_dointvec_minmax"]
                 assert os.path.abspath(f.mod.llvm) == snap_dir + \
-                    "/kernel/sysctl.ll"
+                    "/kernel/sysctl.bc"
             assert f.tag == "proc handler"
             assert f.glob_var is None
 
@@ -163,7 +163,7 @@ def test_add_fun_none_group():
     snap = Snapshot.create_from_source(source, output_dir,
                                        "function", True, False)
 
-    mod = LlvmModule("net/core/skbuff.ll")
+    mod = LlvmModule("net/core/skbuff.bc")
     snap.add_fun("___pskb_trim", mod)
 
     assert "___pskb_trim" in snap.fun_groups[None].functions
@@ -181,7 +181,7 @@ def test_add_fun_sysctl_group():
     snap = Snapshot.create_from_source(source, output_dir,
                                        "sysctl", True, False)
 
-    mod = LlvmModule("kernel/sched/debug.ll")
+    mod = LlvmModule("kernel/sched/debug.bc")
     snap.add_fun("sched_debug_header",
                  mod,
                  "sysctl_sched_latency",
@@ -210,16 +210,16 @@ def test_get_modules():
                                        "sysctl", True, False)
 
     snap.add_fun("sched_proc_update_handler",
-                 LlvmModule("kernel/sched/fair.ll"), None,
+                 LlvmModule("kernel/sched/fair.bc"), None,
                  "proc_handler", "kernel.sched_latency_ns")
-    snap.add_fun("proc_dointvec_minmax", LlvmModule("kernel/sysctl.ll"),
+    snap.add_fun("proc_dointvec_minmax", LlvmModule("kernel/sysctl.bc"),
                  None,
                  "proc_handler", "kernel.timer_migration")
 
     modules = snap.modules()
     assert len(modules) == 2
-    assert set([m.llvm for m in modules]) == {"kernel/sched/fair.ll",
-                                              "kernel/sysctl.ll"}
+    assert set([m.llvm for m in modules]) == {"kernel/sched/fair.bc",
+                                              "kernel/sysctl.bc"}
 
 
 def test_get_by_name_functions():
@@ -230,8 +230,8 @@ def test_get_by_name_functions():
     snap = Snapshot.create_from_source(source, output_dir,
                                        "function", True, False)
 
-    mod_buff = LlvmModule("net/core/skbuff.ll")
-    mod_alloc = LlvmModule("mm/page_alloc.ll")
+    mod_buff = LlvmModule("net/core/skbuff.bc")
+    mod_alloc = LlvmModule("mm/page_alloc.bc")
     snap.add_fun("___pskb_trim", mod_buff)
     snap.add_fun("__alloc_pages_nodemask", mod_alloc)
 
@@ -250,9 +250,9 @@ def test_get_by_name_sysctls():
                                        "sysctl", True, False)
 
     mod_fair = LlvmModule(
-        "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sched/fair.ll")
+        "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sched/fair.bc")
     mod_sysctl = LlvmModule(
-        "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sysctl.ll")
+        "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sysctl.bc")
     snap.add_fun("sched_proc_update_handler", mod_fair, None, "proc handler",
                  "kernel.sched_latency_ns")
     snap.add_fun("proc_dointvec_minmax", mod_sysctl, None, "proc handler",
@@ -273,9 +273,9 @@ def test_filter():
     snap = Snapshot.create_from_source(source, output_dir,
                                        "function", True, False)
 
-    snap.add_fun("___pskb_trim", LlvmModule("net/core/skbuff.ll"))
+    snap.add_fun("___pskb_trim", LlvmModule("net/core/skbuff.bc"))
     snap.add_fun("__alloc_pages_nodemask",
-                 LlvmModule("mm/page_alloc.ll"))
+                 LlvmModule("mm/page_alloc.bc"))
 
     snap.filter(["__alloc_pages_nodemask"])
     assert len(snap.fun_groups[None].functions) == 1
@@ -299,9 +299,9 @@ def test_to_yaml_functions():
                                        "function", True, False)
 
     snap.add_fun("___pskb_trim", LlvmModule(
-        "snapshots/linux-3.10.0-957.el7/net/core/skbuff.ll"))
+        "snapshots/linux-3.10.0-957.el7/net/core/skbuff.bc"))
     snap.add_fun("__alloc_pages_nodemask", LlvmModule(
-        "snapshots/linux-3.10.0-957.el7/mm/page_alloc.ll"))
+        "snapshots/linux-3.10.0-957.el7/mm/page_alloc.bc"))
 
     yaml_str = snap.to_yaml()
     yaml_snap = yaml.safe_load(yaml_str)
@@ -318,9 +318,9 @@ def test_to_yaml_functions():
 
     for f in yaml_dict["list"]:
         if f["name"] == "___pskb_trim":
-            assert f["llvm"] == "net/core/skbuff.ll"
+            assert f["llvm"] == "net/core/skbuff.bc"
         elif f["name"] == "__alloc_pages_nodemask":
-            assert f["llvm"] == "mm/page_alloc.ll"
+            assert f["llvm"] == "mm/page_alloc.bc"
 
 
 def test_to_yaml_sysctls():
@@ -341,11 +341,11 @@ def test_to_yaml_sysctls():
     snap.add_fun("sched_proc_update_handler",
                  LlvmModule(
                      "snapshots-sysctl/linux-3.10.0-957.el7/"
-                     "kernel/sched/fair.ll"),
+                     "kernel/sched/fair.bc"),
                  None, "proc handler", "kernel.sched_latency_ns")
     snap.add_fun("proc_dointvec_minmax",
                  LlvmModule(
-                     "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sysctl.ll"),
+                     "snapshots-sysctl/linux-3.10.0-957.el7/kernel/sysctl.bc"),
                  None, "proc handler", "kernel.timer_migration")
 
     yaml_str = snap.to_yaml()
@@ -365,14 +365,14 @@ def test_to_yaml_sysctls():
         if g["sysctl"] == "kernel.sched_latency_ns":
             assert g["functions"][0] == {
                 "name": "sched_proc_update_handler",
-                "llvm": "kernel/sched/fair.ll",
+                "llvm": "kernel/sched/fair.bc",
                 "glob_var": None,
                 "tag": "proc handler"
             }
         elif g["sysctl"] == "kernel.timer_migration":
             assert g["functions"][0] == {
                 "name": "proc_dointvec_minmax",
-                "llvm": "kernel/sysctl.ll",
+                "llvm": "kernel/sysctl.bc",
                 "glob_var": None,
                 "tag": "proc handler"
             }
diff --git a/tests/unit_tests/source_tree_test.py b/tests/unit_tests/source_tree_test.py
index 099f704fd..1ebd8f0ec 100644
--- a/tests/unit_tests/source_tree_test.py
+++ b/tests/unit_tests/source_tree_test.py
@@ -30,7 +30,7 @@ def test_get_module_for_symbol(source):
     """
     mod = source.get_module_for_symbol("__alloc_workqueue_key")
     assert mod is not None
-    assert mod.llvm == os.path.join(source.source_dir, "kernel/workqueue.ll")
+    assert mod.llvm == os.path.join(source.source_dir, "kernel/workqueue.bc")
     assert mod.has_function("__alloc_workqueue_key")
 
 
@@ -41,7 +41,7 @@ def test_get_module_for_symbol_built_after(source):
     The LLVM file should not be retrieved.
     """
     before_time = datetime.datetime.now() - datetime.timedelta(minutes=1)
-    llvm_file = os.path.join(source.source_dir, "kernel/workqueue.ll")
+    llvm_file = os.path.join(source.source_dir, "kernel/workqueue.bc")
 
     # Temporarily change mtime of the LLVM IR file to now
     stat = os.stat(llvm_file)
@@ -60,7 +60,7 @@ def test_get_module_for_symbol_built_after(source):
 def test_get_module_for_symbol_fail(source):
     """Test getting LLVM module for a non-existing function definition."""
     with pytest.raises(SourceNotFoundException):
-        source.get_module_for_symbol("__get_user_2")
+        source.get_module_for_symbol("__get_user_3")
 
 
 def test_get_modules_using_symbol(source):
@@ -71,8 +71,8 @@ def test_get_modules_using_symbol(source):
     assert len(mods) == 2
     assert set([m.llvm for m in mods]) == \
         set([os.path.join(source.source_dir, f)
-             for f in ["net/core/sock.ll",
-                       "net/netfilter/ipvs/ip_vs_sync.ll"]])
+             for f in ["net/core/sock.bc",
+                       "net/netfilter/ipvs/ip_vs_sync.bc"]])
 
 
 def test_copy_source_files(source):
@@ -87,8 +87,8 @@ def test_copy_source_files(source):
         assert os.path.isdir(os.path.join(tmp_source.source_dir, d))
 
     # Check that files were successfully copied.
-    for f in ["net/core/utils.c", "net/core/utils.ll", "kernel/workqueue.c",
-              "kernel/workqueue.ll", "include/linux/module.h",
+    for f in ["net/core/utils.c", "net/core/utils.bc", "kernel/workqueue.c",
+              "kernel/workqueue.bc", "include/linux/module.h",
               "include/linux/kernel.h"]:
         assert os.path.isfile(os.path.join(tmp_source.source_dir, f))