diff --git a/build/moz.configure/toolchain.configure b/build/moz.configure/toolchain.configure
index f6e29a4238d9..cf64d7bfd7ce 100755
--- a/build/moz.configure/toolchain.configure
+++ b/build/moz.configure/toolchain.configure
@@ -1015,9 +1015,9 @@ def compiler(language, host_or_target, c_compiler=None, other_compiler=None,
             if host_or_target.os == 'Android':
                 raise FatalCheckError('GCC is not supported on Android.\n'
                                       'Please use clang from the Android NDK instead.')
-            if info.version < '6.1.0':
+            if info.version < '7.1.0':
                 raise FatalCheckError(
-                    'Only GCC 6.1 or newer is supported (found version %s).'
+                    'Only GCC 7.1 or newer is supported (found version %s).'
                     % info.version)
 
         if info.type == 'clang-cl':
diff --git a/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py b/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
index ef1d59f08a7f..cd57336b5029 100755
--- a/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
+++ b/python/mozbuild/mozbuild/test/configure/test_toolchain_configure.py
@@ -127,9 +127,11 @@ GCC_6 = GCC('6.4.0') + DEFAULT_C11
 GXX_6 = GXX('6.4.0') + DEFAULT_CXX_14 + SUPPORTS_GNUXX17 + SUPPORTS_DRAFT_CXX17_201500_VERSION
 GCC_7 = GCC('7.3.0') + DEFAULT_C11
 GXX_7 = GXX('7.3.0') + DEFAULT_CXX_14 + SUPPORTS_GNUXX17 + SUPPORTS_CXX17
+GCC_8 = GCC('8.3.0') + DEFAULT_C11
+GXX_8 = GXX('8.3.0') + DEFAULT_CXX_14 + SUPPORTS_GNUXX17 + SUPPORTS_CXX17
 
-DEFAULT_GCC = GCC_6
-DEFAULT_GXX = GXX_6
+DEFAULT_GCC = GCC_7
+DEFAULT_GXX = GXX_7
 
 GCC_PLATFORM_LITTLE_ENDIAN = {
     '__ORDER_LITTLE_ENDIAN__': 1234,
@@ -462,7 +464,7 @@ class BaseToolchainTest(BaseConfigureTest):
 
 
 def old_gcc_message(old_ver):
-    return 'Only GCC 6.1 or newer is supported (found version {}).'.format(old_ver)
+    return 'Only GCC 7.1 or newer is supported (found version {}).'.format(old_ver)
 
 
 class LinuxToolchainTest(BaseToolchainTest):
@@ -477,6 +479,8 @@ class LinuxToolchainTest(BaseToolchainTest):
         '/usr/bin/g++-6': GXX_6 + GCC_PLATFORM_X86_64_LINUX,
         '/usr/bin/gcc-7': GCC_7 + GCC_PLATFORM_X86_64_LINUX,
         '/usr/bin/g++-7': GXX_7 + GCC_PLATFORM_X86_64_LINUX,
+        '/usr/bin/gcc-8': GCC_8 + GCC_PLATFORM_X86_64_LINUX,
+        '/usr/bin/g++-8': GXX_8 + GCC_PLATFORM_X86_64_LINUX,
         '/usr/bin/clang': DEFAULT_CLANG + CLANG_PLATFORM_X86_64_LINUX,
         '/usr/bin/clang++': DEFAULT_CLANGXX + CLANG_PLATFORM_X86_64_LINUX,
         '/usr/bin/clang-5.0': CLANG_5_0 + CLANG_PLATFORM_X86_64_LINUX,
@@ -493,20 +497,8 @@ class LinuxToolchainTest(BaseToolchainTest):
     GXX_4_9_RESULT = GCC_4_9_RESULT
     GCC_5_RESULT = old_gcc_message('5.2.1')
     GXX_5_RESULT = GCC_5_RESULT
-    GCC_6_RESULT = CompilerResult(
-        flags=['-std=gnu99'],
-        version='6.4.0',
-        type='gcc',
-        compiler='/usr/bin/gcc-6',
-        language='C',
-    )
-    GXX_6_RESULT = CompilerResult(
-        flags=[],
-        version='6.4.0',
-        type='gcc',
-        compiler='/usr/bin/g++-6',
-        language='C++',
-    )
+    GCC_6_RESULT = old_gcc_message('6.4.0')
+    GXX_6_RESULT = GCC_6_RESULT
     GCC_7_RESULT = CompilerResult(
         flags=['-std=gnu99'],
         version='7.3.0',
@@ -521,8 +513,22 @@ class LinuxToolchainTest(BaseToolchainTest):
         compiler='/usr/bin/g++-7',
         language='C++',
     )
-    DEFAULT_GCC_RESULT = GCC_6_RESULT + {'compiler': '/usr/bin/gcc'}
-    DEFAULT_GXX_RESULT = GXX_6_RESULT + {'compiler': '/usr/bin/g++'}
+    GCC_8_RESULT = CompilerResult(
+        flags=['-std=gnu99'],
+        version='8.3.0',
+        type='gcc',
+        compiler='/usr/bin/gcc-8',
+        language='C',
+    )
+    GXX_8_RESULT = CompilerResult(
+        flags=[],
+        version='8.3.0',
+        type='gcc',
+        compiler='/usr/bin/g++-8',
+        language='C++',
+    )
+    DEFAULT_GCC_RESULT = GCC_7_RESULT + {'compiler': '/usr/bin/gcc'}
+    DEFAULT_GXX_RESULT = GXX_7_RESULT + {'compiler': '/usr/bin/g++'}
 
     CLANG_3_3_RESULT = 'Only clang/llvm 5.0 or newer is supported.'
     CLANGXX_3_3_RESULT = 'Only clang/llvm 5.0 or newer is supported.'
@@ -600,12 +606,12 @@ class LinuxToolchainTest(BaseToolchainTest):
         self.do_toolchain_test(self.PATHS, {
             'c_compiler': self.DEFAULT_GCC_RESULT,
             'cxx_compiler': (
-                'The target C compiler is version 6.4.0, while the target '
-                'C++ compiler is version 7.3.0. Need to use the same compiler '
+                'The target C compiler is version 7.3.0, while the target '
+                'C++ compiler is version 8.3.0. Need to use the same compiler '
                 'version.'),
         }, environ={
             'CC': 'gcc',
-            'CXX': 'g++-7',
+            'CXX': 'g++-8',
         })
 
         self.do_toolchain_test(self.PATHS, {
@@ -613,12 +619,12 @@ class LinuxToolchainTest(BaseToolchainTest):
             'cxx_compiler': self.DEFAULT_GXX_RESULT,
             'host_c_compiler': self.DEFAULT_GCC_RESULT,
             'host_cxx_compiler': (
-                'The host C compiler is version 6.4.0, while the host '
-                'C++ compiler is version 7.3.0. Need to use the same compiler '
+                'The host C compiler is version 7.3.0, while the host '
+                'C++ compiler is version 8.3.0. Need to use the same compiler '
                 'version.'),
         }, environ={
             'CC': 'gcc',
-            'HOST_CXX': 'g++-7',
+            'HOST_CXX': 'g++-8',
         })
 
     def test_mismatched_compiler(self):
@@ -963,6 +969,8 @@ class WindowsToolchainTest(BaseToolchainTest):
         '/usr/bin/g++-5': GXX_5 + GCC_PLATFORM_X86_WIN,
         '/usr/bin/gcc-6': GCC_6 + GCC_PLATFORM_X86_WIN,
         '/usr/bin/g++-6': GXX_6 + GCC_PLATFORM_X86_WIN,
+        '/usr/bin/gcc-7': GCC_7 + GCC_PLATFORM_X86_WIN,
+        '/usr/bin/g++-7': GXX_7 + GCC_PLATFORM_X86_WIN,
         '/usr/bin/clang': DEFAULT_CLANG + CLANG_PLATFORM_X86_WIN,
         '/usr/bin/clang++': DEFAULT_CLANGXX + CLANG_PLATFORM_X86_WIN,
         '/usr/bin/clang-5.0': CLANG_5_0 + CLANG_PLATFORM_X86_WIN,
@@ -1001,6 +1009,8 @@ class WindowsToolchainTest(BaseToolchainTest):
     GXX_5_RESULT = LinuxToolchainTest.GXX_5_RESULT
     GCC_6_RESULT = LinuxToolchainTest.GCC_6_RESULT
     GXX_6_RESULT = LinuxToolchainTest.GXX_6_RESULT
+    GCC_7_RESULT = LinuxToolchainTest.GCC_7_RESULT
+    GXX_7_RESULT = LinuxToolchainTest.GXX_7_RESULT
     DEFAULT_GCC_RESULT = LinuxToolchainTest.DEFAULT_GCC_RESULT
     DEFAULT_GXX_RESULT = LinuxToolchainTest.DEFAULT_GXX_RESULT
 
diff --git a/taskcluster/ci/build/linux.yml b/taskcluster/ci/build/linux.yml
index e1158a78e00e..5a994e0157e5 100644
--- a/taskcluster/ci/build/linux.yml
+++ b/taskcluster/ci/build/linux.yml
@@ -253,7 +253,7 @@ linux64-base-toolchains/opt:
     fetches:
         toolchain:
             - linux64-clang-5.0
-            - linux64-gcc-6
+            - linux64-gcc-7
             - linux64-rust-1.37
             - linux64-cbindgen
             - linux64-sccache
@@ -290,7 +290,7 @@ linux64-base-toolchains/debug:
     fetches:
         toolchain:
             - linux64-clang-5.0
-            - linux64-gcc-6
+            - linux64-gcc-7
             - linux64-rust-1.37
             - linux64-cbindgen
             - linux64-sccache
diff --git a/taskcluster/ci/toolchain/clang-tidy.yml b/taskcluster/ci/toolchain/clang-tidy.yml
index c91a14ccff81..c36bd2e72b06 100644
--- a/taskcluster/ci/toolchain/clang-tidy.yml
+++ b/taskcluster/ci/toolchain/clang-tidy.yml
@@ -40,7 +40,7 @@ linux64-clang-tidy:
     fetches:
         toolchain:
             - linux64-binutils
-            - linux64-gcc-6
+            - linux64-gcc-7
 
 macosx64-clang-tidy:
     index:
@@ -65,7 +65,7 @@ macosx64-clang-tidy:
             - linux64-binutils
             - linux64-cctools-port
             - linux64-clang-9
-            - linux64-gcc-6
+            - linux64-gcc-7
             - linux64-node
 
 win64-clang-tidy:
diff --git a/taskcluster/ci/toolchain/gcc.yml b/taskcluster/ci/toolchain/gcc.yml
index 1427bfeb5290..115d131da0fe 100644
--- a/taskcluster/ci/toolchain/gcc.yml
+++ b/taskcluster/ci/toolchain/gcc.yml
@@ -11,28 +11,13 @@ job-defaults:
             - 'build/unix/build-gcc/build-gcc.sh'
         toolchain-artifact: public/build/gcc.tar.xz
 
-linux64-gcc-6:
-    description: "GCC 6 toolchain build"
-    treeherder:
-        symbol: TL(gcc6)
-    run:
-        script: build-gcc-linux.sh
-        toolchain-alias: linux64-gcc
-    fetches:
-        fetch:
-            - binutils-2.31.1
-            - gcc-6.4.0
-            - gmp-5.1.3
-            - isl-0.15
-            - mpc-0.8.2
-            - mpfr-3.1.5
-
 linux64-gcc-7:
     description: "GCC 7 toolchain build"
     treeherder:
         symbol: TL(gcc7)
     run:
         script: build-gcc-linux.sh
+        toolchain-alias: linux64-gcc
     fetches:
         fetch:
             - binutils-2.31.1
diff --git a/taskcluster/ci/toolchain/gn.yml b/taskcluster/ci/toolchain/gn.yml
index 2b931d795d67..48bd509e36a3 100644
--- a/taskcluster/ci/toolchain/gn.yml
+++ b/taskcluster/ci/toolchain/gn.yml
@@ -25,7 +25,7 @@ linux64-gn:
         script: build-gn-linux.sh
     fetches:
         toolchain:
-            - linux64-gcc-6
+            - linux64-gcc-7
 
 macosx64-gn:
     treeherder:
diff --git a/taskcluster/ci/toolchain/misc.yml b/taskcluster/ci/toolchain/misc.yml
index 3765bf35a046..58678b009f9a 100644
--- a/taskcluster/ci/toolchain/misc.yml
+++ b/taskcluster/ci/toolchain/misc.yml
@@ -35,7 +35,7 @@ linux64-llvm-dsymutil:
         fetch:
             - llvm-for-dsymutil
         toolchain:
-            - linux64-gcc-6
+            - linux64-gcc-7
 
 linux64-binutils:
     description: "Binutils toolchain build"
@@ -116,7 +116,7 @@ linux64-tup:
         fetch:
             - tup
         toolchain:
-            - linux64-gcc-6
+            - linux64-gcc-7
 
 linux64-upx:
     description: "UPX build"