diff --git a/build/docs/supported-configurations.rst b/build/docs/supported-configurations.rst
index cc2c1ea728..eaa18172c6 100644
--- a/build/docs/supported-configurations.rst
+++ b/build/docs/supported-configurations.rst
@@ -52,4 +52,4 @@ packages for popular Linux distributions. ``configure`` will typically
 detect missing dependencies and inform you how to disable features to
 work around unsatisfied dependencies.
 
-Clang 3.3 or GCC 4.4 is required to build the tree.
+Clang 3.3 or GCC 4.7 is required to build the tree.
diff --git a/dom/bindings/ErrorResult.h b/dom/bindings/ErrorResult.h
index 26f64ae3db..5b2e73f440 100644
--- a/dom/bindings/ErrorResult.h
+++ b/dom/bindings/ErrorResult.h
@@ -41,10 +41,6 @@ public:
     mResult = NS_OK;
 
 #ifdef DEBUG
-    // ErrorResult is extremely performance-sensitive code, where literally
-    // every machine instruction matters. Initialize mMessage only to suppress
-    // a debug-only warning from gcc 4.6.
-    mMessage = nullptr;
     mMightHaveUnreportedJSException = false;
 #endif
   }
diff --git a/dom/bluetooth/bluedroid/BluetoothDaemonHelpers.h b/dom/bluetooth/bluedroid/BluetoothDaemonHelpers.h
index 171ab01c2a..8061860aad 100644
--- a/dom/bluetooth/bluedroid/BluetoothDaemonHelpers.h
+++ b/dom/bluetooth/bluedroid/BluetoothDaemonHelpers.h
@@ -13,7 +13,7 @@
 #include "mozilla/ipc/BluetoothDaemonConnection.h"
 #include "nsThreadUtils.h"
 
-#if MOZ_IS_GCC && MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
+#if MOZ_IS_GCC
 /* use designated array initializers if supported */
 #define INIT_ARRAY_AT(in_, out_) \
   [in_] = out_
diff --git a/dom/bluetooth/bluedroid/BluetoothHALHelpers.h b/dom/bluetooth/bluedroid/BluetoothHALHelpers.h
index 6e963463ad..34d89b8839 100644
--- a/dom/bluetooth/bluedroid/BluetoothHALHelpers.h
+++ b/dom/bluetooth/bluedroid/BluetoothHALHelpers.h
@@ -19,7 +19,7 @@
 #include "mozilla/dom/bluetooth/BluetoothTypes.h"
 #include "nsThreadUtils.h"
 
-#if MOZ_IS_GCC && MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
+#if MOZ_IS_GCC
 /* use designated array initializers if supported */
 #define CONVERT(in_, out_) \
   [in_] = out_
diff --git a/dom/bluetooth2/BluetoothCommon.h b/dom/bluetooth2/BluetoothCommon.h
index b3e722e22b..79cf6640f1 100644
--- a/dom/bluetooth2/BluetoothCommon.h
+++ b/dom/bluetooth2/BluetoothCommon.h
@@ -16,7 +16,7 @@ extern bool gBluetoothDebugFlag;
 
 #define SWITCH_BT_DEBUG(V) (gBluetoothDebugFlag = V)
 
-#if MOZ_IS_GCC && MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
+#if MOZ_IS_GCC
 /* use designated array initializers if supported */
 #define INIT_ARRAY_AT(in_, out_) \
   [in_] = out_
diff --git a/dom/plugins/base/npfunctions.h b/dom/plugins/base/npfunctions.h
index 05ce852209..9927258ec5 100644
--- a/dom/plugins/base/npfunctions.h
+++ b/dom/plugins/base/npfunctions.h
@@ -215,8 +215,7 @@ typedef OSErr (*BP_GetSupportedMIMETypesProcPtr)(BPSupportedMIMETypes*, UInt32);
 #endif
 
 #if defined(XP_UNIX)
-/* GCC 3.3 and later support the visibility attribute. */
-#if defined(__GNUC__) && ((__GNUC__ >= 4) || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3))
+#if defined(__GNUC__)
 #define NP_VISIBILITY_DEFAULT __attribute__((visibility("default")))
 #elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
 #define NP_VISIBILITY_DEFAULT __global
diff --git a/js/src/jsapi-tests/tests.h b/js/src/jsapi-tests/tests.h
index 483c6646d2..a85e45d90e 100644
--- a/js/src/jsapi-tests/tests.h
+++ b/js/src/jsapi-tests/tests.h
@@ -142,9 +142,6 @@ class JSAPITest
         return JSAPITestString(JS_VersionToString(v));
     }
 
-    // Note that in some still-supported GCC versions (we think anything before
-    // GCC 4.6), this template does not work when the second argument is
-    // nullptr. It infers type U = long int. Use CHECK_NULL instead.
     template <typename T, typename U>
     bool checkEqual(const T& actual, const U& expected,
                     const char* actualExpr, const char* expectedExpr,
diff --git a/layout/tables/nsTableRowFrame.cpp b/layout/tables/nsTableRowFrame.cpp
index 2592fed133..b5876ada14 100644
--- a/layout/tables/nsTableRowFrame.cpp
+++ b/layout/tables/nsTableRowFrame.cpp
@@ -918,8 +918,7 @@ nsTableRowFrame::ReflowChildren(nsPresContext*          aPresContext,
         kidReflowState.emplace(aPresContext, aReflowState, kidFrame,
                                LogicalSize(kidFrame->GetWritingMode(),
                                            kidAvailSize),
-                               // Cast needed for gcc 4.4.
-                               uint32_t(nsHTMLReflowState::CALLER_WILL_INIT));
+                               nsHTMLReflowState::CALLER_WILL_INIT);
         InitChildReflowState(*aPresContext, kidAvailSize, borderCollapse,
                              *kidReflowState);
 
diff --git a/mfbt/tests/TestMaybe.cpp b/mfbt/tests/TestMaybe.cpp
index f1b098e99e..603b39967b 100644
--- a/mfbt/tests/TestMaybe.cpp
+++ b/mfbt/tests/TestMaybe.cpp
@@ -26,16 +26,6 @@ using mozilla::UniquePtr;
 #if MOZ_IS_MSVC
    template<typename T> struct Identity { typedef T type; };
 #  define DECLTYPE(EXPR) Identity<decltype(EXPR)>::type
-#elif MOZ_IS_GCC
-// Work around a bug in GCC < 4.7 that prevents expressions of
-// the form |decltype(foo)::type| from working. See here:
-// http://stackoverflow.com/questions/14330768/c11-compiler-error-when-using-decltypevar-followed-by-internal-type-of-var
-#  if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
-#    define DECLTYPE(EXPR) decltype(EXPR)
-#  else
-     template<typename T> struct Identity { typedef T type; };
-#    define DECLTYPE(EXPR) Identity<decltype(EXPR)>::type
-#  endif
 #else
 #  define DECLTYPE(EXPR) decltype(EXPR)
 #endif
diff --git a/mozglue/build/SSE.cpp b/mozglue/build/SSE.cpp
index f125d527d7..1a087c70c8 100644
--- a/mozglue/build/SSE.cpp
+++ b/mozglue/build/SSE.cpp
@@ -16,7 +16,6 @@ namespace {
 
 #ifdef HAVE_CPUID_H
 
-// cpuid.h is available on gcc 4.3 and higher on i386 and x86_64
 #include <cpuid.h>
 
 enum CPUIDRegister { eax = 0, ebx = 1, ecx = 2, edx = 3 };
diff --git a/mozglue/build/SSE.h b/mozglue/build/SSE.h
index 1d10cc5bab..7bb8702deb 100644
--- a/mozglue/build/SSE.h
+++ b/mozglue/build/SSE.h
@@ -40,11 +40,6 @@
  *     ...
  *   }
  *
- * Note that these functions depend on cpuid intrinsics only available in gcc
- * 4.3 or later and MSVC 8.0 (Visual C++ 2005) or later, so they return false
- * in older compilers.  (This could be fixed by replacing the code with inline
- * assembly.)
- *
  *
  * USING INTRINSICS
  * ================
diff --git a/netwerk/sctp/src/user_atomic.h b/netwerk/sctp/src/user_atomic.h
index 33659cd226..ef8869a27c 100755
--- a/netwerk/sctp/src/user_atomic.h
+++ b/netwerk/sctp/src/user_atomic.h
@@ -84,10 +84,8 @@ static inline void atomic_init() {} /* empty when we are not using atomic_mtx */
 #endif
 
 #else
-/* Using gcc built-in functions for atomic memory operations
+/* To use gcc built-in functions for atomic memory operations compile with -march=i486
    Reference: http://gcc.gnu.org/onlinedocs/gcc-4.1.0/gcc/Atomic-Builtins.html
-   Requires gcc version 4.1.0
-   compile with -march=i486
  */
 
 /*Atomically add V to *P.*/
diff --git a/nsprpub/pr/include/md/_linux.h b/nsprpub/pr/include/md/_linux.h
index 2a2ad53da0..1b20186df6 100644
--- a/nsprpub/pr/include/md/_linux.h
+++ b/nsprpub/pr/include/md/_linux.h
@@ -151,8 +151,7 @@ extern PRInt32 _PR_ppc_AtomicSet(PRInt32 *val, PRInt32 newval);
 #endif
 
 #if defined(__powerpc64__)
-#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)
-/* Use GCC built-in functions */
+#if (__GNUC__)
 #define _PR_HAVE_ATOMIC_OPS
 #define _MD_INIT_ATOMIC()
 #define _MD_ATOMIC_INCREMENT(ptr) __sync_add_and_fetch(ptr, 1)
diff --git a/nsprpub/pr/include/prtypes.h b/nsprpub/pr/include/prtypes.h
index 52b3ab0b19..2e410d5923 100644
--- a/nsprpub/pr/include/prtypes.h
+++ b/nsprpub/pr/include/prtypes.h
@@ -119,9 +119,7 @@
 
 #else /* Unix */
 
-/* GCC 3.3 and later support the visibility attribute. */
-#if (__GNUC__ >= 4) || \
-    (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
+#if (__GNUC__)
 #define PR_VISIBILITY_DEFAULT __attribute__((visibility("default")))
 #else
 #define PR_VISIBILITY_DEFAULT
diff --git a/nsprpub/pr/src/misc/prdtoa.c b/nsprpub/pr/src/misc/prdtoa.c
index 2276926136..e06eeaa1a3 100644
--- a/nsprpub/pr/src/misc/prdtoa.c
+++ b/nsprpub/pr/src/misc/prdtoa.c
@@ -9,7 +9,7 @@
  * The author of dtoa.c was not willing to add the parentheses suggested by
  * GCC, so we suppress these warnings.
  */
-#if (__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2)
+#if (__GNUC__)
 #pragma GCC diagnostic ignored "-Wparentheses"
 #endif
 
diff --git a/xpcom/ds/nsAtomTable.cpp b/xpcom/ds/nsAtomTable.cpp
index 80d69156c1..b2e508dd1a 100644
--- a/xpcom/ds/nsAtomTable.cpp
+++ b/xpcom/ds/nsAtomTable.cpp
@@ -26,12 +26,8 @@
 
 using namespace mozilla;
 
-#if defined(__clang__)
+#if defined(__clang__) || defined(__GNUC__)
 #  pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
-#elif MOZ_IS_GCC
-#  if MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
-#    pragma GCC diagnostic ignored "-Wdelete-non-virtual-dtor"
-#  endif
 #endif
 
 /**
diff --git a/xpcom/glue/nsISupportsImpl.h b/xpcom/glue/nsISupportsImpl.h
index 59bcafe3bf..d4988fa426 100644
--- a/xpcom/glue/nsISupportsImpl.h
+++ b/xpcom/glue/nsISupportsImpl.h
@@ -156,14 +156,6 @@ private:
 #define MOZ_ASSERT_CLASSNAME(_type)                         \
   static_assert(mozilla::IsClass<_type>::value,             \
                 "Token '" #_type "' is not a class type.")
-// Older versions of gcc can't instantiate local classes in templates.
-// GCC 4.7 doesn't have this problem.
-#if MOZ_IS_GCC
-# if !MOZ_GCC_VERSION_AT_LEAST(4, 7, 0)
-#  undef MOZ_ASSERT_CLASSNAME
-#  define MOZ_ASSERT_CLASSNAME(_type)
-# endif
-#endif
 
 // Note that the following constructor/destructor logging macros are redundant
 // for refcounted objects that log via the NS_LOG_ADDREF/NS_LOG_RELEASE macros.
diff --git a/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp
index f63d0c1e28..49bbd8a45c 100644
--- a/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp
+++ b/xpcom/reflect/xptcall/md/unix/xptcstubs_arm_openbsd.cpp
@@ -9,15 +9,9 @@
 #include "xptiprivate.h"
 
 #ifdef __GNUC__
-/* This tells gcc3.4+ not to optimize away symbols.
- * @see http://gcc.gnu.org/gcc-3.4/changes.html
+/* This tells GCC not to optimize away symbols.
  */
 #define DONT_DROP_OR_WARN __attribute__((used))
-#else
-/* This tells older gccs not to warn about unused vairables.
- * @see http://docs.freebsd.org/info/gcc/gcc.info.Variable_Attributes.html
- */
-#define DONT_DROP_OR_WARN __attribute__((unused))
 #endif
 
 /* Specify explicitly a symbol for this function, don't try to guess the c++ mangled symbol.  */