diff --git a/compiler/rustc_codegen_gcc/.github/workflows/ci.yml b/compiler/rustc_codegen_gcc/.github/workflows/ci.yml
index 73ec6b84a155e..f96912e6b7a83 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/ci.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/ci.yml
@@ -13,14 +13,14 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     strategy:
       fail-fast: false
       matrix:
         libgccjit_version:
-          - { gcc: "gcc-13.deb" }
-          - { gcc: "gcc-13-without-int128.deb" }
+          - { gcc: "gcc-15.deb" }
+          - { gcc: "gcc-15-without-int128.deb" }
         commands: [
           "--std-tests",
           # FIXME: re-enable asm tests when GCC can emit in the right syntax.
@@ -108,13 +108,13 @@ jobs:
         cargo clippy --all-targets --features master -- -D warnings
 
   duplicates:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
       - run: python tools/check_intrinsics_duplicates.py
 
   build_system:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-24.04
     steps:
       - uses: actions/checkout@v4
       - name: Test build system
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/failures.yml b/compiler/rustc_codegen_gcc/.github/workflows/failures.yml
index f33d9fcc58257..d080bbfe91fe6 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/failures.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/failures.yml
@@ -13,7 +13,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     strategy:
       fail-fast: false
@@ -56,12 +56,12 @@ jobs:
 
     - name: Download artifact
       if: matrix.libgccjit_version.gcc != 'libgccjit12.so'
-      run: curl -LO https://github.com/rust-lang/gcc/releases/latest/download/gcc-13.deb
+      run: curl -LO https://github.com/rust-lang/gcc/releases/latest/download/gcc-15.deb
 
     - name: Setup path to libgccjit
       if: matrix.libgccjit_version.gcc != 'libgccjit12.so'
       run: |
-          sudo dpkg --force-overwrite -i gcc-13.deb
+          sudo dpkg --force-overwrite -i gcc-15.deb
           echo 'gcc-path = "/usr/lib"' > config.toml
           echo "LIBRARY_PATH=/usr/lib" >> $GITHUB_ENV
           echo "LD_LIBRARY_PATH=/usr/lib" >> $GITHUB_ENV
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/gcc12.yml b/compiler/rustc_codegen_gcc/.github/workflows/gcc12.yml
index 4c2ce91e86eef..bb9e020dc6a4c 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/gcc12.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/gcc12.yml
@@ -17,7 +17,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     strategy:
       fail-fast: false
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml b/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
index 07bb372b3606d..ed1fc02bd9131 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/m68k.yml
@@ -17,7 +17,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     strategy:
       fail-fast: false
@@ -47,17 +47,17 @@ jobs:
     - name: Install packages
       run: |
         sudo apt-get update
-        sudo apt-get install qemu qemu-user-static
+        sudo apt-get install qemu-system qemu-user-static
 
     - name: Download artifact
-      run: curl -LO https://github.com/cross-cg-gcc-tools/cross-gcc/releases/latest/download/gcc-m68k-13.deb
+      run: curl -LO https://github.com/cross-cg-gcc-tools/cross-gcc/releases/latest/download/gcc-m68k-15.deb
 
     - name: Download VM artifact
       run: curl -LO https://github.com/cross-cg-gcc-tools/vms/releases/latest/download/debian-m68k.img
 
     - name: Setup path to libgccjit
       run: |
-          sudo dpkg -i gcc-m68k-13.deb
+          sudo dpkg -i gcc-m68k-15.deb
           echo 'gcc-path = "/usr/lib/"' > config.toml
 
     - name: Set env
diff --git a/compiler/rustc_codegen_gcc/.github/workflows/release.yml b/compiler/rustc_codegen_gcc/.github/workflows/release.yml
index 60e0943c87dac..886ce90b4713e 100644
--- a/compiler/rustc_codegen_gcc/.github/workflows/release.yml
+++ b/compiler/rustc_codegen_gcc/.github/workflows/release.yml
@@ -13,7 +13,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
 
     strategy:
       fail-fast: false
@@ -37,11 +37,11 @@ jobs:
       run: sudo apt-get install ninja-build ripgrep
 
     - name: Download artifact
-      run: curl -LO https://github.com/rust-lang/gcc/releases/latest/download/gcc-13.deb
+      run: curl -LO https://github.com/rust-lang/gcc/releases/latest/download/gcc-15.deb
 
     - name: Setup path to libgccjit
       run: |
-          sudo dpkg --force-overwrite -i gcc-13.deb
+          sudo dpkg --force-overwrite -i gcc-15.deb
           echo 'gcc-path = "/usr/lib/"' > config.toml
 
     - name: Set env
@@ -76,4 +76,9 @@ jobs:
     - name: Run y.sh cargo build
       run: |
         EMBED_LTO_BITCODE=1 CHANNEL="release" ./y.sh cargo build --release --manifest-path tests/hello-world/Cargo.toml
-        # TODO: grep the asm output for "call my_func" and fail if it is found.
+        call_found=$(objdump -dj .text tests/hello-world/target/release/hello_world | grep -c "call .*mylib.*my_func" ) ||:
+        if [ $call_found -gt 0 ]; then
+          echo "ERROR: call my_func found in asm"
+          echo "Test is done with LTO enabled, hence inlining should occur across crates"
+          exit 1
+        fi
diff --git a/compiler/rustc_codegen_gcc/build_system/src/build.rs b/compiler/rustc_codegen_gcc/build_system/src/build.rs
index d0ced211a6169..e98377f15a945 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/build.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/build.rs
@@ -150,6 +150,8 @@ pub fn build_sysroot(env: &HashMap<String, String>, config: &ConfigInfo) -> Resu
         "debug"
     };
 
+    // We have a different environment variable than RUSTFLAGS to make sure those flags are only
+    // sent to rustc_codegen_gcc and not the LLVM backend.
     if let Ok(cg_rustflags) = std::env::var("CG_RUSTFLAGS") {
         rustflags.push(' ');
         rustflags.push_str(&cg_rustflags);
@@ -184,8 +186,12 @@ pub fn build_sysroot(env: &HashMap<String, String>, config: &ConfigInfo) -> Resu
 fn build_codegen(args: &mut BuildArg) -> Result<(), String> {
     let mut env = HashMap::new();
 
-    env.insert("LD_LIBRARY_PATH".to_string(), args.config_info.gcc_path.clone());
-    env.insert("LIBRARY_PATH".to_string(), args.config_info.gcc_path.clone());
+    let gcc_path =
+        args.config_info.gcc_path.clone().expect(
+            "The config module should have emitted an error if the GCC path wasn't provided",
+        );
+    env.insert("LD_LIBRARY_PATH".to_string(), gcc_path.clone());
+    env.insert("LIBRARY_PATH".to_string(), gcc_path);
 
     if args.config_info.no_default_features {
         env.insert("RUSTFLAGS".to_string(), "-Csymbol-mangling-version=v0".to_string());
diff --git a/compiler/rustc_codegen_gcc/build_system/src/config.rs b/compiler/rustc_codegen_gcc/build_system/src/config.rs
index 37b4b68950e49..4f9fcc9715140 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/config.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/config.rs
@@ -112,7 +112,7 @@ pub struct ConfigInfo {
     pub sysroot_panic_abort: bool,
     pub cg_backend_path: String,
     pub sysroot_path: String,
-    pub gcc_path: String,
+    pub gcc_path: Option<String>,
     config_file: Option<String>,
     // This is used in particular in rust compiler bootstrap because it doesn't run at the root
     // of the `cg_gcc` folder, making it complicated for us to get access to local files we need
@@ -173,6 +173,14 @@ impl ConfigInfo {
             "--release-sysroot" => self.sysroot_release_channel = true,
             "--release" => self.channel = Channel::Release,
             "--sysroot-panic-abort" => self.sysroot_panic_abort = true,
+            "--gcc-path" => match args.next() {
+                Some(arg) if !arg.is_empty() => {
+                    self.gcc_path = Some(arg.into());
+                }
+                _ => {
+                    return Err("Expected a value after `--gcc-path`, found nothing".to_string());
+                }
+            },
             "--cg_gcc-path" => match args.next() {
                 Some(arg) if !arg.is_empty() => {
                     self.cg_gcc_path = Some(arg.into());
@@ -260,8 +268,9 @@ impl ConfigInfo {
             create_symlink(&libgccjit_so, output_dir.join(&format!("{}.0", libgccjit_so_name)))?;
         }
 
-        self.gcc_path = output_dir.display().to_string();
-        println!("Using `{}` as path for libgccjit", self.gcc_path);
+        let gcc_path = output_dir.display().to_string();
+        println!("Using `{}` as path for libgccjit", gcc_path);
+        self.gcc_path = Some(gcc_path);
         Ok(())
     }
 
@@ -273,6 +282,15 @@ impl ConfigInfo {
     }
 
     pub fn setup_gcc_path(&mut self) -> Result<(), String> {
+        // If the user used the `--gcc-path` option, no need to look at `config.toml` content
+        // since we already have everything we need.
+        if let Some(gcc_path) = &self.gcc_path {
+            println!(
+                "`--gcc-path` was provided, ignoring config file. Using `{}` as path for libgccjit",
+                gcc_path
+            );
+            return Ok(());
+        }
         let config_file = match self.config_file.as_deref() {
             Some(config_file) => config_file.into(),
             None => self.compute_path("config.toml"),
@@ -283,12 +301,15 @@ impl ConfigInfo {
             self.download_gccjit_if_needed()?;
             return Ok(());
         }
-        self.gcc_path = match gcc_path {
-            Some(path) => path,
-            None => {
-                return Err(format!("missing `gcc-path` value from `{}`", config_file.display(),));
-            }
+        let Some(gcc_path) = gcc_path else {
+            return Err(format!("missing `gcc-path` value from `{}`", config_file.display()));
         };
+        println!(
+            "GCC path retrieved from `{}`. Using `{}` as path for libgccjit",
+            config_file.display(),
+            gcc_path
+        );
+        self.gcc_path = Some(gcc_path);
         Ok(())
     }
 
@@ -299,10 +320,17 @@ impl ConfigInfo {
     ) -> Result<(), String> {
         env.insert("CARGO_INCREMENTAL".to_string(), "0".to_string());
 
-        if self.gcc_path.is_empty() && !use_system_gcc {
-            self.setup_gcc_path()?;
-        }
-        env.insert("GCC_PATH".to_string(), self.gcc_path.clone());
+        let gcc_path = if !use_system_gcc {
+            if self.gcc_path.is_none() {
+                self.setup_gcc_path()?;
+            }
+            self.gcc_path.clone().expect(
+                "The config module should have emitted an error if the GCC path wasn't provided",
+            )
+        } else {
+            String::new()
+        };
+        env.insert("GCC_PATH".to_string(), gcc_path.clone());
 
         if self.cargo_target_dir.is_empty() {
             match env.get("CARGO_TARGET_DIR").filter(|dir| !dir.is_empty()) {
@@ -381,6 +409,8 @@ impl ConfigInfo {
         }
 
         // This environment variable is useful in case we want to change options of rustc commands.
+        // We have a different environment variable than RUSTFLAGS to make sure those flags are
+        // only sent to rustc_codegen_gcc and not the LLVM backend.
         if let Some(cg_rustflags) = env.get("CG_RUSTFLAGS") {
             rustflags.extend_from_slice(&split_args(&cg_rustflags)?);
         }
@@ -414,7 +444,7 @@ impl ConfigInfo {
             "{target}:{sysroot}:{gcc_path}",
             target = self.cargo_target_dir,
             sysroot = sysroot.display(),
-            gcc_path = self.gcc_path,
+            gcc_path = gcc_path,
         );
         env.insert("LIBRARY_PATH".to_string(), ld_library_path.clone());
         env.insert("LD_LIBRARY_PATH".to_string(), ld_library_path.clone());
@@ -459,6 +489,7 @@ impl ConfigInfo {
     --release-sysroot      : Build sysroot in release mode
     --sysroot-panic-abort  : Build the sysroot without unwinding support
     --config-file          : Location of the config file to be used
+    --gcc-path             : Location of the GCC root folder
     --cg_gcc-path          : Location of the rustc_codegen_gcc root folder (used
                              when ran from another directory)
     --no-default-features  : Add `--no-default-features` flag to cargo commands
diff --git a/compiler/rustc_codegen_gcc/build_system/src/info.rs b/compiler/rustc_codegen_gcc/build_system/src/info.rs
index ea38791d38c9a..bd891de2eb4c0 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/info.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/info.rs
@@ -14,6 +14,8 @@ pub fn run() -> Result<(), String> {
     }
     config.no_download = true;
     config.setup_gcc_path()?;
-    println!("{}", config.gcc_path);
+    if let Some(gcc_path) = config.gcc_path {
+        println!("{}", gcc_path);
+    }
     Ok(())
 }
diff --git a/compiler/rustc_codegen_gcc/build_system/src/main.rs b/compiler/rustc_codegen_gcc/build_system/src/main.rs
index 3a860e2b1360c..393617183061b 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/main.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/main.rs
@@ -34,11 +34,11 @@ Options:
         --help    : Displays this help message.
 
 Commands:
-        cargo     : Executes a cargo command. 
+        cargo     : Executes a cargo command.
         rustc     : Compiles the program using the GCC compiler.
         clean     : Cleans the build directory, removing all compiled files and artifacts.
         prepare   : Prepares the environment for building, including fetching dependencies and setting up configurations.
-        build     : Compiles the project. 
+        build     : Compiles the project.
         test      : Runs tests for the project.
         info      : Displays information about the build environment and project configuration.
         clone-gcc : Clones the GCC compiler from a specified source.
diff --git a/compiler/rustc_codegen_gcc/build_system/src/test.rs b/compiler/rustc_codegen_gcc/build_system/src/test.rs
index 0e790a4befc9b..6c29c7d1825b9 100644
--- a/compiler/rustc_codegen_gcc/build_system/src/test.rs
+++ b/compiler/rustc_codegen_gcc/build_system/src/test.rs
@@ -1229,8 +1229,11 @@ pub fn run() -> Result<(), String> {
 
     if !args.use_system_gcc {
         args.config_info.setup_gcc_path()?;
-        env.insert("LIBRARY_PATH".to_string(), args.config_info.gcc_path.clone());
-        env.insert("LD_LIBRARY_PATH".to_string(), args.config_info.gcc_path.clone());
+        let gcc_path = args.config_info.gcc_path.clone().expect(
+            "The config module should have emitted an error if the GCC path wasn't provided",
+        );
+        env.insert("LIBRARY_PATH".to_string(), gcc_path.clone());
+        env.insert("LD_LIBRARY_PATH".to_string(), gcc_path);
     }
 
     build_if_no_backend(&env, &args)?;
diff --git a/compiler/rustc_codegen_gcc/libgccjit.version b/compiler/rustc_codegen_gcc/libgccjit.version
index ff58accec1d4c..417fd5b03935d 100644
--- a/compiler/rustc_codegen_gcc/libgccjit.version
+++ b/compiler/rustc_codegen_gcc/libgccjit.version
@@ -1 +1 @@
-45648c2edd4ecd862d9f08196d3d6c6ccba79f07
+e607be166673a8de9fc07f6f02c60426e556c5f2
diff --git a/compiler/rustc_codegen_gcc/messages.ftl b/compiler/rustc_codegen_gcc/messages.ftl
index 85fa17a6ba501..882fff8673a19 100644
--- a/compiler/rustc_codegen_gcc/messages.ftl
+++ b/compiler/rustc_codegen_gcc/messages.ftl
@@ -5,9 +5,6 @@ codegen_gcc_unknown_ctarget_feature_prefix =
 codegen_gcc_invalid_minimum_alignment =
     invalid minimum global alignment: {$err}
 
-codegen_gcc_lto_not_supported =
-    LTO is not supported. You may get a linker error.
-
 codegen_gcc_forbidden_ctarget_feature =
     target feature `{$feature}` cannot be toggled with `-Ctarget-feature`: {$reason}